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ON THE STUDY OF HIGH GAIN AND STEERABLE
MILLIMETRE-WAVE PLASMONIC ANTENNA
A dissertation submitted to The University of Manchester for the degree of Master of
Science in the Faculty of Engineering and Physical Sciences
2013
SHAKER M.M ALKARAKI
SCHOOL OF ELECTRICAL AND ELECTRONIC
ENGINEERING
Table of Contents
LIST OF FIGURES .............................................................................................................................. iv
LIST OF TABLES ................................................................................................................................ ix
ABSTRACT......................................................................................................................................... x
DECLARATION ................................................................................................................................. xi
INTELLECTUAL PROPERTY STATEMENT.......................................................................................... xii
DEDICATION ...................................................................................................................................xiii
ACKNOWLEDGMENT ......................................................................................................................xiv
CHAPTER 1 ....................................................................................................................................... 1
INTRODUCTION ................................................................................................................................ 1
1.1 Background ............................................................................................................................ 1
1.2 Aims and objectives ............................................................................................................... 2
1.3 Instrumentation and methodology........................................................................................ 3
1.4 Context ................................................................................................................................... 4
CHAPTER 2 ....................................................................................................................................... 5
LITERATURE REVIEW ........................................................................................................................ 5
2.1 Basics of surface plasmons .................................................................................................... 5
2.2 Existing studies on plasmonic antennas ................................................................................ 7
2.3 Plasmonic antenna beam steering....................................................................................... 10
2.4 Theory of waveguides .......................................................................................................... 12
2.5 Antenna parameters ............................................................................................................ 13
CHAPTER 3 ..................................................................................................................................... 15
MILLIMETRE WAVE PLASMONIC ANTENNA SIMULATION AND ANALYSIS .................................... 15
3.1 Single element patch antenna design .................................................................................. 15
3.2 Millimetre-wave plasmonic antenna design and analysis ................................................... 17
3.3 60 GHz band plasmonic antenna design .............................................................................. 20
3.31 Single element patch antenna design ............................................................................ 20
............................................................................................................................................... 21
3.32 60 GHz band millimetre-wave plasmonic antenna ........................................................ 21
CHAPTER 4 ..................................................................................................................................... 24
MILLIMETRE WAVE STEERABLE PLASMONIC ................................................................................. 24
ANTENNA DESIGN .......................................................................................................................... 24
4.1 Steer the antenna’s beam by introducing two cross slots on both slit sides ...................... 24
4.2 Steer the antenna’s beam by introducing two rectangular slots ........................................ 26
4.3 Steer the antenna’s beam by introducing three elliptical slots ........................................... 32
ii
CHAPTER 5 ..................................................................................................................................... 33
DIRECTLY COUPLED AND STEERABLE MILLIMETRE WAVE PLASMONIC ANTENNA ....................... 33
5.1 Directly coupled and steerable slit grating millimetre-wave plasmonic antenna design .... 33
5.1.1 Directly coupled slit grating millimetre-wave plasmonic antenna design .................... 33
5.1.2 Steer the antenna’s beam by introducing two identical rectangular slots ................... 36
5.2 Bull’s eye millimetre-wave plasmonic antenna with rectangular slit .................................. 39
5.4 Bull’s eye millimetre-wave plasmonic antenna with circular slit ........................................ 41
CHAPTER 6 ..................................................................................................................................... 45
CONCLUSIONS AND FUTURE WORK .............................................................................................. 45
6.1 Conclusions .......................................................................................................................... 45
6.2 Recommendations for future work ..................................................................................... 46
REFERENCES ................................................................................................................................... 47
APPENDIX A .................................................................................................................................... 49
CLAIM OF POSSIBLE PUBLICATION................................................................................................. 49
APPENDIX B .................................................................................................................................... 50
RECTANGULAR PATCH ANTENNA DESIGN ..................................................................................... 50
APPENDIX C .................................................................................................................................... 51
FEASIBILITY STUDY REPORT ........................................................................................................... 51
(Word Count for Thesis‟ Body/Total for thesis: 10977/17092)
iii
LIST OF FIGURES
Figure 1.1: Highly directive plasmonic antenna designed by structuring the metal surface.
2
Figure 2.1: Spoof SPs between metal and dielectric material at metal interface [8].
5
Figure 2.2: (a) A block of PEC which is periodically cut through by one dimensional slit. (b)
Periodic rectangular holes drilled in the PEC, where the length of the hole is,
is the width and
is the period [10].
6
Figure 2.3: Plasmonic antenna structures composed of subwavelength apertures. (a) Bull‟s eye
structure (b) slit grating structure[11].
7
Figure 2.4: (a) 1 D Periodic corrugated Structure, (b) Spoof plasmon structure with subwavelength minor grooves in the surface.
is the major groove‟s period,
is the major
groove‟s width and is the major groove‟s depth [6].
8
Figure 2.5: Aperture of the single slit antenna bounded by two grooves. The EM wave is incident
as the
rectangular waveguide mode[14].
8
Figure 2.6: Model of the proposed antenna integrated with the corrugated grooves. (a) Top view.
(b) Front view.[15]
9
Figure 2.7: Geometry of the corrugated directive slot antenna, (a) Top view; (b) Side view.
P=11.8mm, P1=9.1mm, w=2.4mm, d=2.7mm, t=1.5mm [16].
9
Figure 2.8: (a) top view of theBull‟s Eye Antenna (b) cross section of the antenna with parameters
=12mm , =11.54mm, =17mm, =10mm and
=3.4mm[7].
Figure 2.9: Configuration of the slit groove structure [17].
10
10
Figure 2.10: Electric field radiation from an optical nano-reflector array[17]. (a) and (b) The
beam when grooves have different depth. (c) The beam when the grooves filled by different
dielectric [17].
11
Figure2.11: Non-Symmetreical Steerable Plasmonic Antenna[5].
11
Figure 2.12: Polar coordinate representation of far-field gain radiation pattern for non symmetrical structure[5].
11
Figure 2.13: Common waveguide structures. (a) Rectangular waveguide. (b) Circular
waveguide.[18]
12
iv
Figure 3.1: Model of The rectangular patch antenna.
15
Figure 3.2: Simulated
16
parameter of the proposed patch antenna.
Figure 3.3: Simulated 3D far-field radiation pattern of the patch antenna.
16
Figure 3.4: Simulated 2D polar coordinate of the far-field of the patch antenna.
16
Figure 3.5: Configuration of the millimetre-wave plasmonic antenna that resonates at 12 GHz. 17
Figure 3.6: Front view of the designed plasmonic antenna.
17
Figure 3.7: Simulated
18
parameter of the plasmonic antenna.
Figure 3.8: Simulated 3D far-fieled radiation pattern of the proposed antenna.
18
Figure 3.9: Simulated 2D polar coordinate of the far-field of the plasmonic antenna.
18
Figure 3.10: Simulated 3D far-fieled radiation pattern of the proposed antenna without grooves.19
Figure 3.11: simulated 3D radiation pattern of the proposed antenna with upper grooves only. 19
Figure 3.12: The relationship between the grooves number and the antenna gain.
20
Figure 3.13: Simulated far-field pattern of the 60GHz band patch antenna.
(a) 2D polar coordinate. (b) 3D far-field radiation pattern.
21
Figure 3.14: Simulated
22
parameter of the 60 GHz band plasmonic antenna.
Figure 3.15: Simulated far-field radiation pattern of the 60GHz band plasmonic antenna.
(a) 3D far-field radiation pattern. (b) 2D polar coordinate.
Figure 3.16: E-field polarization along the z-axis.
22
22
Figure 3.16: H-field polarization along the z-axis.23
Figure3.17: Distribution of the surface current on the proposed plamonic antenna.
23
Figure 4.1: The configuration of the proposed antenna, C = 3mm , D = 3mm, E = 0.8mm, Cross1
= 7.7mm , Cross2 = 5.3mm.
24
Figure 4.2: Simulated 3D far-field radiation pattern of the proposed steerable plasmonic
antenna.
25
Figure 4.3: Simulated 2D polar coordinate of the far-field of the proposed steerable plasmonic
antenna.
25
v
Figure 4.4: Parametric study for the effect of the position of the 1 st cross on the proposed
antenna‟s beam steer-ability.
26
Figure 4.5: Parametric study for the effect of the position of the 2 nd cross on the proposed
antenna‟s beam steer-ability.
26
Figure 4.6: The configuration of the proposed antenna, SW1= 40mm, X1=1.9mm , X2= 4mm,
E =1mm .
27
Figure 4.7: Simulated 3D far-field radiation pattern of the steerable plasmonic antenna with the
two rectangular slots.
27
Figure 4.8: The effect of the position of first rectangualr slot on the antenna‟s resonant
frequency.
28
Figure 4.9: The effect of the position of the 2nd rectangualr slot on the antenna‟s resonant
frequency.
28
Figure 4.10: Simulated 2D far-field polar coordinate of the proposed antenna radiation pattern.
(a) At resonance frequency (b) At 62.5GHz.
28
Figure 4.11: The effect of the position of 1st rectangualr slot on the antenna‟s radiation pattern. 29
Figure 4.12: The effect of the position of 2nd rectangualr slot on the antenna‟s radiation pattern. 29
Figure 4.13: The effect of the width of the two rectangular slot on the antenna radiation pattern.29
Figure 4.14: the proposed antenna‟s simulated gain performance over the operation frequency. 30
Figure 4.15: E-field polarization on the proposed antenna surface.
(a) Symmetrical structure with no rectangular slots.
(b) Symmetrical structure with presence of two rectangular slots.
30
Figure 4.16: H-field polarization on the proposed antenna with presence of two rectangular slots
slots.
31
Figure 4.17: Distribution of the surface current on the proposed antenna. (a) without slots (b)with
slots.
31
Figure 4.18: The configuration of the proposed antenna.
32
Figure 4.19: Simulated far-field radiation pattern of the proposed antenna. (a) 3D far-field
radiation pattern. (b) 2D polar coordinate.
32
vi
Figure 5.1: The slit grating antenna geometry. (a) Front view (b) Top view.
33
Figure 5.2: Simulated
34
parameter of the proposed slit grating plasmonic antenna.
Figure 5.3: The simulated far-field radiation pattern of the proposed antenna. (a) 2D polar
coordinates. (b) 3D radiation pattern.
34
Figure 5.4: The slit grating antenna‟s simulated gain over the operation bandwidth.
35
Figure 5.5: The geometry of the proposed antenna, X1 = 1.5mm, X2=2.9mm, E=0.55mm,
S=40mm,SW=2.35mm,SL=0.2mm.
36
Figure 5.6: Simulated
36
parameter of the proposed antenna.
Figure 5.7: The simulated far-field radiation pattern of the proposed antenna design at resonance
frequency. (a) 3D radiation pattern. (b) 3D radiation pattern. (c) 2D polar coordinates.
37
Figure 5.8: The steerable slit grating antenna‟s simulated gain over the operation bandwidth.
37
Figure 5.9: The proposed antenna surface current density at resonance frequency.
38
Figure 5.10: The geometry of the proposed antenna C = 6mm, SL =0.2mm, SW= 2.37mm.
38
Figure 5.11: Simulated 2D polar coordinates of the proposed antenna‟s radiation pattern.
(a) C = 6mm, (b) C = -6mm.
39
Figure 5.12: The effect of the position of the slit on the antenna‟s far-field radiation pattern.
39
Figure 5.13: Bull Eye millimetre wave antenna. (a) Front view (b) Top view.
40
Figure 5.14: Simulated
parameter of the proposed Bull‟s eye antenna.
40
Figure 5.15: The simulated far-field pattern of the Bull Eye antenna at resonance frequency.
(a) 3D radiation pattern. (b) 2D polar coordinates.
41
Figure 5.16: The Bull Eye antenna gain performance over the entire operation bandwidth.
42
Figure 5.17: Top of View of the proposed antenna C = 2mm.
42
Figure 5.18: The simulated far-field radiation pattern of Bull‟s eye antenna with unsymmetrical
slit position at resonance frequency. (a) 3D radiation pattern. (b) 2D polar coordinates.
42
Figure 5.19: Top view of the proposed Bull‟s eye antenna with circular slit.
43
Figure 5.20: Simulated
parameter of the proposed plasmonic antenna between 57GHz and
300GHz.
43
Figure 5.21: The proposed antenna‟s gain performance between 60GHz and 70GHz.
44
vii
Figure 5.22: The proposed antenna‟s gain performance between 57 GHz and 300GHz.
Figure 5.23: Simulated
44
parameter of the proposed Bull‟s eye antenna
between 57GHz and 300GHz.
44
Figure 5.24: The far-field radiation pattern of the Bull‟s eye millimetre-wave plasmonic antenna
with circular slit at some selected frequencies.(a) 3D at 90 GHz. (b) 2D at 90 GHz.
(c) 3D at 200 GHz. (d) 2D at 200 GHz. (e) 3D at 300 GHz. (f) 2D at 300 GHz.
45
Figure 5.25: The simulated 2D polar coordinates of the far-field radiation pattern of the steerable
Bull‟s eye antenna at 64GHz.
46
viii
LIST OF TABLES
Table 2.1: Values of
for TE modes of a circular waveguide [19]
13
Table 3.1: Description of rectangular patch antenna parameters
15
Table 3.2: Description of the plasmonic antenna parameters
17
Table 3.3: description of rectangular patch antenna parameters
20
Table 3.4: Description of the 60 GHz plasmonic antenna parameters
21
Table 4.1: The proposed antenna‟s performance with and without the crosses
25
Table 5.1: The slit grating antenna parameters and specifications
34
Table 5.2: The proposed antenna‟s performance with different feeding methods
35
Table 5.3: The Bull‟s eye plasmonic antenna parameters and specifications
40
Table 5.4: The proposed antenna parameters and specifications
43
Table 5.5: Comparison between the slit grating and Bull‟s eye millimetre-wave plasmonic
antennas
45
ix
ABSTRACT
This research presents an investigation about the design considerations and the beam steer-ability
of millimetre-wave plasmonic antennas by modelling and designing steerable slit grating
millimetre-wave plasmonic antenna and steerable Bull‟s eye millimetre-wave plasmonic antenna.
Millimetre-wave plasmonic antennas are designed by structuring the metal surface with certain
patterns that enables the electromagnetic waves to be confined into dimensions smaller than the
wavelength and that boost the antenna directivity and gain. Recently, plasmonic antennas have
shown promising characteristics that make them an impressive future alternative of phased array
antennas for millimetre-wave applications. Plasmonic antennas have the capability to produce
directive and steerable beam as efficient as array antennas with lower cost and less complex
design. Novel techniques have been implemented to steer the millimetre-wave plamonic antennas
beam; meanwhile, these new powerful techniques were able to steer the proposed antennas beam
for up to 20˚. Surprisingly, one of the proposed techniques was capable not only to steer the
antenna beam, but also to enhance the antenna gain at the same time. Finally, a novel Bull‟s eye
millimetre-wave plasmonic antenna has an impedance bandwidth of more than 350% is designed
and simulated. The suggested Bull‟s eye antenna bandwidth ranges from 57GHz to more than
300GHz.
x
DECLARATION
I hereby declare that:
No portion of the work referred to in the dissertation has been submitted in support of an
application for another degree or qualification of this or any other university or other institute
of learning.
xi
INTELLECTUAL PROPERTY STATEMENT
I.
The author of this dissertation (including any appendices and/or schedules to this
dissertation) owns certain copyright or related rights in it (the “Copyright”) and s/he
has given The University of Manchester certain rights to use such Copyright,
including for administrative purposes.
II.
Copies of this dissertation, either in full or in extracts and whether in hard or
electronic copy, may be made only in accordance with the Copyright, Designs and
Patents Act 1988 (as amended) and regulations issued under it or, where appropriate,
in accordance with licensing agreements which the University has entered into. This
page must form part of any such copies made.
III.
The ownership of certain Copyright, patents, designs, trade marks and other
intellectual property (the “Intellectual Property”) and any reproductions of copyright
works in the dissertation, for example graphs and tables (“Reproductions”), which
may be described in this dissertation, may not be owned by the author and may be
owned by third parties. Such Intellectual Property and Reproductions cannot and
must not be made available for use without the prior written permission of the
owner(s) of the relevant Intellectual Property and/or Reproductions.
IV.
Further information on the conditions under which disclosure, publication and
commercialisation of this dissertation, the Copyright and any Intellectual Property
and/or Reproductions described in it may take place is available in the University IP
Policy (see http://documents.manchester.ac.uk/display.aspx?DocID=487), in any
relevant Dissertation restriction declarations deposited in the University Library, The
University
Library‟s
regulations
(see
http://www.manchester.ac.uk/library/aboutus/regulations) and in The University‟s
Guidance for the Presentation of Dissertations.
xii
DEDICATION
This work is dedicated to my beloved parents Majdi and Manal Alkaraki.
xiii
ACKNOWLEDGMENT
I would like to express my great gratitude to my supervisor Dr. Zhirun Hu for giving me
this opportunity to work on this research under his supervision. I would like to thank him for the
endless guidance and support that he has provided to me. I am so thankful for his great attention
and help that he has given to tackle all the problems that I faced during my work.
I would like to deeply thank Hani Qaddumi Scholarship Foundation (HQSF) for funding
my Master‟s study at the University of Manchester, specially Miss. Rana Diab , Mrs. Afifah
Kittaneh and Mr. Bassam Shakhshir.
Finally, I would also like to thank my parents and members of my family for their
prayers.
xiv
CHAPTER 1
INTRODUCTION
1.1 Background
Data are transmitted in the wireless communication systems via electromagnetic
waves. The coupling between electronic circuit and electromagnetic waves is achieved by
antennas which are the sole interface between the hardware and radio frequency transmission
environment. Antenna design proved to have a major impact over the wireless system reliability
and cost. Hence, the efficiency of the wireless system will be enhanced by better antenna design
that is capable of producing highly directive beam.
As wireless technology industry has developed, millimetre and microwave applications
have rapidly grown to satisfy the need of this industry. Millimetre wave directive antennas are
widely used in in ad hoc network to save energy and to boost the system‟s capacity. The use of
the aforementioned antennas will improve the network throughput and will cut the energy
dissipation as well [1]. Directive antennas are able to increase the link capacity, enhance the
security through decreasing accessibility and boost the bandwidth efficiency in both military and
civil mobile networks [2].
The design of millimetre steerable directive antenna is a crucial requirement in the
design of radar and imaging systems and such antennas that have high gain and steerable beam
capabilities are essential. Particularly, it is vital that the antenna beam is steerable without being
physically rotating the antenna itself for many applications. Recently, steerable and directive
antennas have been widely employed in biomedical applications such as: cancer detection,
because of their high penetration and resolution characteristics [3].
The well-known optical antenna design concepts and procedures can be investigated to be
used for the design of millimetre-wave antennas. The main target of any antenna whether
operating on radio frequencies (RF) or on optical frequencies is to radiate and receive
electromagnetic energy [4]. Plasmonic antennas have been proposed for optical applications and
it exploits the surface wave plasmonic phenomenon to produce highly directive radiation beam.
Despite the fact that phased array antennas have proven their mettle and capability to
provide adaptive beam steering with high gain, the design complexity and high cost of those
antennas are its main drawbacks. Hence, the promising characteristics of plasmonic antennas
make them an impressive future alternative of phased array antennas for millimetre-wave
applications.
1
Plasmonic antennas have the capability to produce directive beam as efficient as array
antennas with lower cost and less complex design, but the beam steer-ability of plasmonic
antennas remains one of the main challenges in the field of antenna designs.
Surface Plasmons (SPs) enable the electromagnetic field to be confined in dimensions
that are smaller than the wavelength. SPs have received a great attention from scientists and
engineers to design highly directive antennas to operate on optical and microwave frequencies.
Generally, plasmonic antennas are designed by structuring the metal surface in certain patterns
that boost the antenna directivity and gain as shown in Figure 1.1.
Figure 1.1: Highly directive plasmonic antenna designed by structuring
the metal surface.
1.2 Aims and objectives
The aim of this project is to study and investigate high gain and steer-ability of millimeterwave antennas by controlling and directing radiation at metal surfaces through spoof surface
plasmons phenomenon. The main objectives of the project are outlined as follows:

To understand the basic concept of „spoof‟ surface plasmon and plasmonic antennas.

To design and simulate Bull‟s Eye or other type of plasmonic millimetre-wave antennas.

To perform parametric simulation to analyze the performance of beam steering capability
of the plasmonic antennas.

To investigate the coupling mechanism between the launching antenna and plasmonic
one.

To investigate the possibility of direct coupling from the circuit or waveguide to the
plasmonic antenna.
2
1.3 Instrumentation and methodology
The analysis and thorough study of existing research related to plasmonic antenna design
to produce directive beam provides basic antenna structure that will be modelled and will be used
as a frame work for this research
The software package „CST Microwave Studio (CSTMWS)‟ is used to evaluate and test
the performance of the suggested antenna. CST is powerful software that enables antenna
engineers to simulate antenna performance and various antenna parameters such as: the input
reflection coefficient (
), directivity, gain, 2D and 3D radiation patterns. The parametric sweep
facility provided by CST is used to test the effect of different antenna parameters on the proposed
design for different geometrical structures. The sequence of simulation and design is as follows:
i.
An existing and preliminarily design of spoof plasmonic antenna based on existing
structures from [5], [6] and [7] will be modelled and simulated using CST to resonate at
12GHz.
ii.
The initial antenna design which is based on slit grating structure plasmonic fed by patch
antenna is optimized by utilizing sweep parameter provided by CST. Optimization will
be carried out through extensive parametric study for antenna parameters such as:
a. Metal thickness of the plasmonic antenna.
b. Distance between the coupling patch and the plasmonic antenna.
c. Depth and width of each groove.
d. Groove‟s number and period.
e. Shape of the grooves.
f.
iii.
Slit dimensions, position and slit shape.
The optimized and final antenna design that resonates at 12 GHz will be used as a
reference to design millimetre wave plasmonic antenna which operates on the 60 GHz
band.
iv.
Steer the beam of the designed 60GHz slit grating plasmonic antenna by introducing
empirical slots on the antenna‟s aperture.
v.
Designing directly coupled slit grating plasmonic antenna where the coupling is achieved
by rectangular waveguide.
vi.
Steer the beam of the directly coupled antenna by introducing empirical slots on the
antenna‟s aperture and by changing the position of the slit.
vii.
Designing Bull‟s eye millimetre-wave plasmonic antenna with rectangular slit that
operate on the 60 GHz band.
viii.
ix.
Steer the beam of the Bull‟s eye antenna by changing the position of the slit.
Re-designing the Bull‟s eye antenna with circular slit instead of the rectangular one and
steer the beam of the antenna by changing the circular slit position.
3
1.4 Context
The report comprises of six chapters as follows:
Chapter 1 is an introduction to the project including a relevant background, aims and
objectives, methodology, instrumentation and report organization.
Chapter 2 contains explores the literature review of the concepts behind plasmonic
antenna and fundamentals of surface plasmon phenomenon. Followed by a comprehensive
conducted survey about the existing techniques related to the design of directive and steerable
millimetre wave antenna is conducted.
Chapter 3 presents the designs of two millimetre wave plasmonic antennas based on slit
grating structure. The first antenna design resonates on 12 GHz, while the second resonates on the
60 GHz band. Both plasmonic antennas are fed by two rectangular patch antennas.
Comprehensive analysis on the radiation mechanism of the proposed antennas is carried out too.
Chapter 4 presents novel techniques that are used to steer the beam of the 60 GHz band
slit grating plasmonic antenna that was previously designed in chapter 3.
Chapter 5 demonstrates the design of directly coupled and steerable plasmonic antennas.
Two different antenna structures are presented in this chapter which are slit grating and Bull Eye.
Both antennas operate on 60 GHz band and the electromagnetic energy is coupled to both of them
using rectangular and circular waveguides.
Finally, chapter 6 offers the project conclusion about the design of steerable millimetre
wave antenna and shed lights on future work on the study.
4
CHAPTER 2
LITERATURE REVIEW
2.1 Basics of surface plasmons
Metals such as silver and copper support spoof surface plasmons (SPs) which are
electromagnetic surface waves that propagate between the surface of metal and dielectric as
shown in Figure 2.1 .The waves are localized near the surface and they originate from the free
electrons of the metal. Surface plasmons have shown potential applications recently in subwavelength optics, biophotonics, microscopy, optical antennas and biological sensors [8] [9].
Figure 2.1: Spoof SPs between metal and dielectric material at metal interface [8].
Usually electromagnetic waves cannot propagate into dimensions that are smaller than
the wavelength due to diffraction limit. The localization of incident waves to the metal surface
can be controlled by introducing corrugated structures that enable the incident waves to be guided
and confined into the slit that has smaller dimensions than the incident wavelength, due to surface
the plasmons phenomenon [5].
Zirchao and Ruan have proposed a surface plasmon-like wave guide, at which half of the
maximum electric field intensity of the surface plasmon mode wave is confined in a 0.20
0.10
sub-wavelength waveguide,
is the wavelength in vacuum. The proposed wave guide is
presented in Figure 2.2 [10].
5
Figure 2.2: (a) A block of PEC which is periodically cut through by one dimensional slit. (b)
Periodic rectangular holes drilled in the PEC, where the length of the hole, is the width and
is the period [10].
As illustrated in Figure 2.2(b), periodic rectangular holes are drilled in the PEC metal
surface and considering the case λ
.The guided electric field inside the holes is described
in equation 1 and it is zero inside the PEC.
[
]
(2.1)
Where, x, y, z are the Cartesian coordinates,
frequency.
√
,
is a constant,
is the
is the wave vector along the z direction and given by [3]:
√
Where,
and
⁄
(2.2)
are the permeability and the permittivity of any material that filling the
holes.
The periodic rectangular hole acts as a square waveguide with a cut off frequency equals to the
surface plasma frequency as shown in equation [5]:
(2.3)
√
It has been demonstrated that periodic corrugations in metal surface will increase the
momentum associated with surface plasmon and will enhance the directivity of the radiated beam
due to surface plasmon constructive interference. Surface plasmons enable antenna designer to
focus incident beam into an open structure to produce directive beam. So, the ability of surface
plasmon to generate higher wave beam than the incident wave is exploited in high gain antenna
design.
6
2.2 Existing studies on plasmonic antennas
One of the interesting SPs applications is the plasmonic antennas which have great
capability of extreme light and electromagnetic beam concentration. Among these antennas,
structures that consist of sub-wavelength apertures flanked by surface corrugations which are
called as two dimensional slit grating structure and three dimensional Bull‟s eye structure as
shown in Figure 2.3[11].
Figure 2.3: Plasmonic antenna structures composed of sub-wavelength apertures. (a) Bull’s eye
structure (b) Slit grating structure [11].
The above suggested corrugated structures have a great capability to improve the
transmission of electromagnetic waves at microwave and optical frequencies due to constructive
interference of resonating spoof plasmonic modes. Besides, these modes can be manipulated by
changing the structure parameters such as period and depth of the grooves. The grooves have the
ability to redirect incident waves to the sub-wavelength apertures through exciting surface wave
in the form of surface plasmons. Then, these waves are refocused by the aperture and the
transmission gets extremely enhanced [12]. This approach is well known in the design of optical
and THz high gain antennas, but it has been recently exploited to design high gain millimetre
microwave antennas.
Several studies have been conducted on plasmonic antennas for optical and THz
applications; meanwhile, few studies are available on plasmonic antennas for millimetre-wave
applications [13]. A study by Haofei et al. has employed spoof surface plasmons phenomenon to
design an antenna that operates from 8.2 to 12.5 GHz. Haofei has verified the role of spoof
surface plasmon by introducing minor sub-wavelength grooves of period smaller than 1/10th of
the operation wavelength. In the designed antenna shown in Figure 2.4, the feed source is
converted into radiated wave via the corrugated structure and the antenna‟s far-field properties
depends on the diffraction of surface waves [6]. The suggested antenna is based on the following
dimensions,
=30mm, =5mm , =4.5mm, =1.2mm and =2.38mm.
7
Figure 2.4: (a) 1 D periodic corrugated Structure, (b) Spoof plasmon structure with subwavelength minor grooves in the surface.
is the major groove’s period, is the major
groove’s width and is the major groove’s depth [6].
The given two expressions represent the far-field scattering properties of the given
grating structure:
(2.4)
(2.5)
Where,
is the wave vector of the incident wave,
wave vector of surface wave and in this case ,
is the diffraction angle,
, and
is the
are the diffraction orders on
each side. According to the authors[6], the radiated enegy is going to be concentrated and
maximized when the condition
is met, because the diffraction order from both
sides will have the same divergence angle.
M. Beruete et al have suggested a very low profile corrugated feeder antenna made of
sub- wavelength aperture and bounded by two grooves as shown in Figure 2.5. The suggested
antenna fed by standard waveguide and it resonates at 16 GHz [14].
Figure 2.5: Aperture of the single slit antenna bounded by two grooves.
The EM wave is incident as the 𝑻𝑬𝟎𝟏 rectangular waveguide mode [14].
8
The antenna gain has been enhanced by 4.3 dB after the grooves addition to reach 10.43
dB at resonance frequency. The groove resonates when its depth is
and this
explains the enhancement of the antenna gain.
One study has proposed a sub-wavelength corrugated grooves antenna as shown in Figure
2.6. The proposed antenna is similar to the slit grating structure previously shown in Figure
2.3(b). The proposed antenna dimensions are: groove period p = 20mm, groove width w =
2.8mm, and groove depth d = 3.6mm. The antenna has four slits which is in size of 11.5mm
2
mm are fed by different four rectangular waveguides [15].
Figure 2.6: Model of the proposed antenna integrated with the corrugated
grooves. (a) Top view. (b) Front view. [15]
Introducing the corrugated structure has enhanced the antenna gain by about 11 dB and it
has reduced the back-lobe level by 10dB. Another study has suggested a highly directive slot
antenna with dielectric loaded surface .The proposed antenna has symmetrical periodic grating
(grooves) on dual sides of the slot and the slot is directly fed by a waveguide as an exciting
source. A dielectric layer with high dielectric constant ( =9.8) is loaded between neighbouring
grating in order to reduce the antenna aperture. The proposed antenna is shown in Figure 2.7 and
has a gain of 18.1dBi at frequency of 14.5GHz [16].
Figure 2.7: Geometry of the corrugated directive slot antenna, (a) Top view; (b) Side view.
P=11.8mm, P1=9.1mm, w=2.4mm, d=2.7mm, t=1.5mm [16].
9
Another study has proposed a millimetre Bull‟s eye corrugated antenna directly fed by a
wave guide feeder. The proposed antenna is presented in Figure 2.8 and it has two resonant
frequencies at 16GHz and 12GHz with a gain of 15dBi at 16GHz [7].
Figure 2.8: (a) top view of the Bull’s Eye Antenna (b) cross section of the antenna with
parameters 𝒉=12mm, 𝒂=11.54mm, 𝒅=17mm, 𝒍=10mm and 𝒘=3.4mm[7].
The author reported that the slit‟s depth ,h=12mm, determines the longitudinal resonant
frequency of the antenna at 16GHz, while the lower resonant frequency at 12GHz is determined
by the slit‟s width. The width of every grating and the grating period
control the angle where
plasmonic like constructive interference takes place, hence both control the antenna‟s gain.
Finally, the author demonstrated practically that the same non corrugated flat metallic structure
has very low gain with nearly isotropic radiation pattern.
2.3 Plasmonic antenna beam steering
Liu et al presented an ultralow profile nano antenna reflectors at which the optical
radiation and emission is manipulated through the plasmonic interaction with light.
In the
proposed reflector design the beam radiation is steered by assigning different sets of groove‟s
depths on sliver substrate that is shown in Figure 2.9[17].
Figure 2.9: Configuration of the slit groove structure [17].
10
The reflector beam is steered to 10 ˚ and 30˚, when the grooves have different depths as
shown in Figure 2.10(a) and Figure 2.11(b), however, Filling the grooves by dielectric materials
that have different dielectric constant will steer the beam to 10˚ as shown in figure 2.10(c).
Figure 2.10: Electric field radiation from an optical nano-reflector array[17]. (a) and (b)
The beam when grooves have different depth. (c) The beam when the grooves filled by
different dielectric[17].
Finally, the only study which could be found on the design of Millimetre-wave plasmonic
antenna has shown that introducing non symmetrical corrugated structure as shown in Figure 2.11
will steer the plasmonic antenna beam by 5˚ as shown in Figure 2.12. The suggested antenna
resonates at 9 GHz with linear gain of 14.1(11.5dB) [5].
Figure2.11: Non-Symmetreical Steerable Plasmonic Antenna[5]
Figure 2.12: Polar coordinate representation of far-field gain radiation
pattern for non-symmetrical structure[5].
In the proposed design, the electromagnetic radiation will be concentrated in the nonsymmetrical side of the antenna because of spoof surface plasmon‟s effect and will focus the
radiated beam at that direction.
11
2.4 Theory of waveguides
Waveguides are hollow and empty metals that used to transfer (guide) electromagnetic
energy from one place to another. Both rectangular and circular waveguides cannot propagate
TEM mode, but can propagate TM and TE modes, because of the presence of one conductor only
[19].
(a)
(b)
Figure 2.13: Common waveguide structures. (a) Rectangular waveguide. (b)
Circular waveguide.[18]
Waveguide acts as a high pass filter with a cut off frequency below which propagation is
impossible. The cut off frequency of the rectangular waveguide is given by [19]:
√(
Where,
)
( )
(2.6)
is the velocity of light in vacuum.
The waveguide dominant mode is the mode with the lowest cut off frequency
lowest
occurs for the
mode for the rectangular wave guide with
, the
is given by [19]:
(2.7)
Thus the mode
lowest
is the dominant TE mode for rectangular waveguide, while the
for the circular wave guide can be given as:
(2.8)
Where
is given in Table 2.1:
12
Table 2.1: Values of
for TE modes of a circular waveguide [19]
n
o
3.832
7.016
10.174
1
1.841
5.331
8.536
2
3.054
6.706
9.970
So the first propagating mode in the circular wave guide is the one that has smallest
which is found in table 2.1 to be
mode. Thus,
waveguide. (In circular waveguide there is no
since
,
is the dominant mode in the circular
).
2.5 Antenna parameters
The performance of the designed antennas in this project is going to be analysed in terms of:
1)
parameter
is the input port voltage reflection coefficient and it is the ratio of the reflected wave to
the incident wave.
2) Bandwidth
In this research, antenna‟s bandwidth is defined as the range of frequencies that the designed
antenna operates successfully according to a predetermined standard which is -10dB.
3) Radiation pattern
The antenna radiation pattern is defined as ”the spatial distribution of a quantity that
characterises the electromagnetic field generated by antenna” [20]. The antenna radiation pattern
is determined in the far-field region and it can be two or three dimensional spatial distribution of
power density, gain, directivity etc.
4) Beam width
The beam width is the angle around zero point around the main beam. However, half power
beam width (3dB) is:”In a radiation pattern cut containing the direction of the maximum of a
lobe, the angle between the two directions in which the radiation intensity is one-half the
maximum value” [20].
13
5) Directivity
Directivity is a parameter that describes the enhancement of the power density in the
maximum radiation direction with respect to the radiation of an isotrope, at distance r in the field
region. The directivity of an antenna is defined with respect to the radiated power when it
compared to isotrope[21].
6) Gain
Antenna‟s gain is quite similar to the antenna‟s directivity; meanwhile, it is defined with
respect to the input power delivered to the antenna. So unlike gain, directivity depends on the
structure of the antenna, and does not depend on the efficiency of a given antenna. To find out the
amount of power transferred from the antenna to the space, the antenna gain is used rather than
the directivity [21].
The gain of the antenna is defined as:
G=ηD
(2.9)
Where, η is the radiation efficiency of the antenna. Gain is always less than directivity because η
lies in the range 0 < η < 1.
14
CHAPTER 3
MILLIMETRE WAVE PLASMONIC ANTENNA SIMULATION AND
ANALYSIS
In this chapter, two slit grating millimetre-wave plasmonic antennas operate at 12GHz
and at 60GHz band are designed, optimized and simulated using
CST MICROWAVE
STUDIO® (CST MWS). CST is powerful software that enables antenna engineers to simulate
antenna performance and various antenna‟s parameters such as: return loss (
), directivity, gain
and radiation patterns. Both designed plasmonic antennas are fed by normal rectangular
microstrip patch antenna. Moreover, the design considerations and analysis of the proposed
antennas are presented and analysed.
3.1 Single element patch antenna design
Single element patch antenna is designed based on transmission line model. The patch‟s
width has a minor effect on the resonant frequency and it has a major effect on the antenna‟s
bandwidth and radiation pattern; meanwhile, the patch‟s length controls the resonant frequency
[21].The resonant frequency of the patch antenna is chosen to be 12GHz .The model of the
designed antenna is illustrated in Figure 3.1 and detailed antenna‟s parameters are shown in Table
3.1.
Figure 3.1: Model of The rectangular patch antenna.
Table 3.1: Description of rectangular patch antenna parameters
Patch Length L = 4.77mm.
Inset depth
Patch width W = 5mm.
Inset width = 1.5 mm.
=1.5mm.
Substrate thickness = 1.6 mm.
Substrate dielectric constant = 5.2.
Feed Line Width
= 0.80 mm.
Antenna Geometry = 10mm
15
8.5mm.
The proposed patch antenna has been optimized using parametric study to resonate
accurately at 12GHz. As shown in Figure 3.2 the patch‟s bandwidth is 430MHz and it has a
simulated gain of 3.88 (5.89 dB) at 12GHz as presented in Figure 3.3 and Figure 3.4.
Figure 3.2: Simulated 𝑺𝟏𝟏 parameter of the proposed patch antenna.
Figure 3.3: Simulated 3D far-field radiation pattern of the patch antenna.
Figure 3.4: Simulated 2D polar coordinate of the far-field of the patch
antenna.
16
3.2 Millimetre-wave plasmonic antenna design and analysis
The patch antenna is used to couple electromagnetic energy to the plasmonic antenna as
illustrated in Figure 3.5. The geometrical dimensions of the designed antenna structure are
elaborated in Table 3.2. The plasmonic antenna can be placed in the near field or in the far-field
of the patch antenna[5].In the proposed design, the plasmonic antenna is placed in the near field
of the patch antenna with a distance of 3.9 mm ( /6).
The bottom structured surface of the plasmonic antenna collects the patch‟s output beam
and guide it into the slit. Excitation of the surface plasmon by creating periodic grooves on the
bottom and top of the plasmonic helps to confine the patch‟s output beam into the slit. Moreover,
the grooves which are on the top of the plasmonic antenna help to produce highly directive beam
as shown in Figure 3.8.
Figure 3.5: Configuration of the millimetre-wave plasmonic antenna that resonates at 12 GHz.
Figure 3.6: Front view of the designed plasmonic antenna.
Table 3.2: Description of the plasmonic antenna parameters
Dimensions of the whole Geometry W
= 240 mm
L
Distance between patch and plasmonic antenna =
3.7 mm.
100 mm.
Dimension of the slit = 2 mm
Groove‟s depth Gd = 5 mm.
20 mm.
Groove‟s period P = 22.6 mm.
Distance between slit and 1st groove A = 10.4 mm.
Groove‟s width GW = 5mm.
Thickness of the plasmonic antenna T = 12 mm.
17
The designed plasmonic antenna resonates at 11.97 GHz with a bandwidth of 148 MHz
and poor
parameter, which is equal to -11.4 dB at resonance frequency as shown in Figure
3.7 .The proposed antenna is highly directive with a linear gain of 24.38 (13.9 dB) and with a 3dB
angular beam‟s width of 36.4˚ at 11.97GHz as shown in Figure 3.8 and Figure 3.10.
Figure 3.7: Simulated 𝑺𝟏𝟏 parameter of the plasmonic antenna.
Figure 3.8: Simulated 3D far-fieled radiation pattern of the proposed antenna.
Figure 3.9: Simulated 2D polar coordinate of the far-field of the
plasmonic antenna.
To prove that the high directivity of the antenna is because of the surface plasmon
phenomenon, the antenna is simulated without introducing any grooves and one can see that the
antenna has a linear gain of 3.049 (4.84 dB) as shown in Figure 3.10. This non-grating structure is
fed with the same output beam from the patch antenna that was used to feed the corrugated
structure antenna.
18
Figure 3.10: Simulated 3D far-fieled radiation pattern of the proposed antenna without grooves.
Figure 3.10 proves that without introducing grooves on the metal‟s surface, the radiated
electromagnetic energy from the patch is not well confined into the slit and the remaining
confined energy through the slit is not re-directed to produce high directivity.
Introducing grooves on the upper part of the antenna as shown in Figure 3.11 will not
only enable the electromagnetic energy to be well confined into the slit, but it will also highly
produce directive beam and it will rise the antenna gain to be equal to 22.81 (13.6 dB). The final
antenna‟s gain has dropped only by 2 linear (0.35 dB), when the bottom grooves are removed as
shown in Figure 3.11.
Figure 3.11: simulated 3D radiation pattern of the proposed antenna with upper grooves only.
Figure 3.12 illustrates the relationship between the antenna gain and number of grooves
on each slit‟s side. It can be noticed that the antenna‟s gain increases exponentially as the number
of grooves increases up to certain limit which can be called as groove‟s saturation limit. It can be
seen that the saturation groove number is five on each antenna side and the antenna gain
enhancement is weak beyond this limit. So, there is no need to adopt more grooves after reaching
the groove‟s saturation limit to achieve higher gain, since it will increase the antenna physical
size and it will extremely reduce the antenna aperture efficiency.
19
Figure 3.12: The relationship between the grooves number and the antenna gain.
3.3 60 GHz band plasmonic antenna design
There is a great demand for better performing antennas that work on the free and less
congested 60 GHz frequency band. Working on the free 60 GHz band will enable users to use
broader bandwidth and higher data transmission rate. As we move up in frequency, many
challenges arise for antenna designers, particularly, to achieve broad bandwidth with a reasonable
antenna gain [22]. Plasmonic antenna has marvellous characteristics that gives it great capability
of providing highly directive gain with a reasonable bandwidth, therefore the possibility of
designing 60 GHz directive plasmonic antenna will be investigated in this section.
3.31 Single element patch antenna design
Single element patch antenna is designed to resonate at the 60 GHz band using RT
Duroid substrate that has a dielectric constant of 2.2. The patch resonates at 60.2 GHz with a
bandwidth of 2.592 GHz and a gain of 3.893 (5.9dB) at resonance frequency. The patch‟s
parameters are elaborated in table 3.3 and the patch‟s 2D radiation pattern and 3D radiation
patterns are shown in Figure 3.13.
Table 3.3: description of rectangular patch antenna parameters
Patch Length L = 1.73mm.
Inset depth
Patch width W = 2.13mm.
Inset width K = 2 mm.
=1 mm.
Substrate thickness = 1 mm.
Substrate dielectric constant = 2.2.
Feed Line Width
Antenna Geometry W
20
= 10 µm.
L = 2.4mm 2.5 mm.
(b)
(a)
Figure 3.13: Simulated far-field pattern of the 60GHz band patch antenna.
(a) 2D polar coordinate. (b) 3D far-field radiation pattern.
3.32 60 GHz band millimetre-wave plasmonic antenna
Millimetre-wave plasmonic antenna has been designed and optimized according to the
dimensions shown in Table 3.4. The proposed antenna has similar operational principles as the
12GHz antenna that was designed in section 3.2. The antenna is designed to operate at 60 GHz
band and it resonates at 62.2 GHz with a bandwidth of 2.47GHz as shown in Figure 3.14. The
antenna‟s parameters which described in Table 3.4 have been optimized and have been studied
using parametric facility provided by CST to maximize the antenna‟s gain at resonant frequency.
Table 3.4: Description of the 60 GHz plasmonic antenna parameters
Dimension of the whole Geometry W
= 20 mm
Distance between patch and plasmonic antenna =
L
0.84 mm.
41 mm.
Dimension of the slit = 0.6 mm
Groove‟s depth Gd = 0.95 mm.
2.65 mm.
Groove‟s period P = 4.4 mm.
Distance between slit and 1st groove A = 1 mm.
Groove‟s width GW = 0.3mm.
Thickness of the plasmonic antenna T = 1.2mm.
The proposed plasmonic antenna has a simulated gain of 10.4dB (10.99 linear) with a
3dB angular beam‟s width of 31.8˚ at resonant frequency. The patch antenna is placed in the near
field of the plasmonic antenna and the distance between the patch and the plasmonic is set to be
less than ( /5). The plasmonic antenna
parameter is shown in Figure 3.14, while the antenna‟s
far-field radiation pattern is shown in Figure 3.15.
21
Figure 3.14: Simulated 𝑺𝟏𝟏 parameter of the 60 GHz band plasmonic antenna.
(b)
(a)
Figure 3.15: Simulated far-field radiation pattern of the 60GHz band plasmonic antenna.
(a) 3D far-field radiation pattern. (b) 2D polar coordinate.
To understand and analyse the radiation mechanism of the designed antenna, the electric field and
magnetic field distribution will be studied at the antenna‟s surface. The designed antenna resonate
at 62.2 GHz, thus the operation wavelength λ is 4.82 mm ,while, the slit dimensions are 0.6
mm
2.65 mm which is smaller than λ . It has been found experimentally that the directivity of
the antenna is maximized when the groove‟s period P ≈ λ (P=4.4mm). The antenna‟s electric field
distribution which is presented in Figure 3.16 shows that the electromagnetic waves is re-emitted
and re-directed by the grooves with help of plasmonic waves on both slit sides.
Figure 3.16: E-field polarization along the z-axis.
22
When the groove period is closed to the operational wavelength λ, the electromagnetic
and plasmonic waves will be re-directed in phase equals to P and constructive interference occurs
to cause peak of transmission. It has been noticed experimentally that if the grooves period is
much smaller or much bigger than the operational wavelength, the antenna‟s gain will drop
exponentially, because of the destructive interference caused by each groove radiation. Moreover,
in the proposed design the slit is considered the primary radiation source and the grooves are the
other 10 secondary radiation sources. Hence, the energy radiation from the secondary sources is
coherently super-positioned with the radiation from the primary source to produce highly
directive beam in the zero direction as the antenna has symmetrical physical structure.
The magnetic field distribution of the proposed antenna is shown in Figure 3.16 and the
surface current density of the antenna is shown in Figure 3.17. It can be noticed that the electric
field, magnetic field and surface current are concentrated mainly beside the slit‟s first and second
groove side. Besides, the aforementioned fields and current distribution are less concentrated after
the first two grooves as illustrated in Figure 3.15, Figure 3.16 and Figure 3.17. However, the
antenna is so sensitive to any change of those parameters and that explain why the millimetrewave plasmonic antenna gain is extremely dependent on the 1st and 2nd groove‟s addition as
previously shown in Figure 3.12.
Figure 3.16: H-field polarization along the z-axis.
Figure3.17: Distribution of the surface current on the proposed plamonic antenna.
23
CHAPTER 4
MILLIMETRE WAVE STEERABLE PLASMONIC
ANTENNA DESIGN
It has been shown that the beam of millimetre-wave plasmonic antenna can be controlled
by introducing unsymmetrical corrugated structures on each slit side [1]. This technique has
proven its capability to steer the beam of the millimetre-wave plasmonic antenna for a certain
limit and it could steer the antenna beam up to 5° [1]. Novel techniques will be presented and
implemented in this chapter and the following one to steer the beam of the millimetre -wave
plasmonic antenna with a better performance than the aforementioned technique carried out in
similar research.
The patch antenna designed in section 3.31 is used to feed and couple the electromagnetic
energy to the proposed plasmonic antennas presented in this chapter. Besides, all proposed
antennas in this chapter operate at the 60GHz band.
4.1 Steer the antenna’s beam by introducing two cross slots on both slit sides
Two slots in the shape of cross are introduced on each antenna side to make the antenna‟s
beam steerable. Introducing the two crosses steers the antenna‟s beam for up to 10° on the whole
antenna‟s bandwidth. The designed antenna resonates at 62.1 GHz and it has a bandwidth of 2.44
GHz with a realized gain of 9.95 dB at resonance frequency. The proposed antenna which is
shown in Figure 4.1 has the same dimensions as the antenna presented in section 3.32. In
addition, introducing the two crosses slightly changes the antenna‟s resonance frequency and
parameter characteristics, while it effectively changes the antenna‟s far-field radiation.
Figure 4.1: The configuration of the proposed antenna, C = 3mm , D = 3mm, E = 0.8mm,
Cross1 = 7.7mm , Cross2 = 5.3mm.
24
The two crosses have identical dimensions which are: D=3mm , C=3mm , E=0.8mm, and
the 1st cross is 7.7mm away from the slit centre while the second is 5.3 mm away from the slit
centre. Comparison of the antenna characteristics pre and post adding the two crosses is shown in
Table 4.1.The far-field radiation patterns of the proposed antenna are shown in Figure 4.2 and
Figure 4.3. It can be seen that the proposed antenna‟s beam is steered by 10˚ as illustrated in
Figure 4.3.
Table 4.1: The proposed antenna’s performance with and without the crosses
Type of the
Resonant
Bandwidth
Simulated
Simulated gain
Minimum
3dB
antenna
frequency
(GHz)
gain at
at resonance
return
Beam
resonance
(dB)
(GHz)
(linear)
loss
width
dB
Without crosses
62.2
2.47
11.1
10.45 dB
-24.67
31.8°
With crosses
62.1
2.44
9.89
9.95 dB
-34
29°
Figure 4.2: Simulated 3D far-field radiation pattern of the proposed
steerable plasmonic antenna.
Figure 4.3: Simulated 2D polar coordinate of the far-field of
the proposed steerable plasmonic antenna.
Figure 4.4 illustrates the effect of the position of the 1st cross on the steer ability of the
proposed antenna. Figure 4.4 shows that introducing the 1st cross makes the antenna beam
steerable by 10°. Introduction and position of the 2nd cross does not affect the beam steerability
of the antenna but it reduces the magnitude of the side lobes as shown in figure 4.5.
25
Figure 4.4: Parametric study for the effect of the position of the 1st cross on
the proposed antenna’s beam steer-ability.
Figure 4.5: Parametric study for the effect of the position of the 2nd cross
on the proposed antenna’s beam steer-ability.
The two added crosses on each slit side will create unsymmetrical electric and magnetic
field distribution along the two slit sides which will make the antenna beam steerable. Addition of
crosses will concentrate the electric and magnetic field on one antenna‟s side as will be studied
and explained in details at the end of the following section.
4.2 Steer the antenna’s beam by introducing two rectangular slots
In the previous section it has been shown that the direction of the beam can be steered for
up to 10° by introducing two cross slots on both slit‟s sides. In this section, it will be shown that
the direction of the beam pattern can be steered for up to 15° by introducing two identical
rectangular slots on any slit‟s side as shown in Figure 4.6. The antenna‟s beam is going to be
steered to the opposite direction of the two slots as presented in Figure 4.7. The proposed antenna
parameters have the same dimensions as the millimetre-wave plasmonic antenna that was
previously designed in section 3.32.
26
Figure 4.6: The configuration of the proposed antenna, SW1= 40mm, X1=1.9mm , X2= 4mm,
E =1mm .
The proposed antenna resonates at 61.7 GHz with a bandwidth of 2.32 GHz ranging from
60.7 GHz to 63.1 GHz. Adding two rectangular slots does not only make antenna beam steerable,
but it also triples the linear antenna gain to 28.2 which is 14.5 dB as shown in figure 4.7.
Figure 4.7: Simulated 3D far-field radiation pattern of the steerable plasmonic antenna
with the two rectangular slots.
Adding the first slot will extremely affect the original antenna‟s resonance frequency,
gain and direction of the main beam. After adding the first slot, the antenna‟s resonance
frequency is shifted by 500MHz from 62.2 GHz to 61.7GHz and the antenna‟s beam is steered by
15°. The proposed antenna has a good return loss of -24.73 dB at resonance frequency as shown
in Figure 4.9. The postion of the 1st rectangular slot affects the
behaviour of the antenna as
presented in figure 4.8. The resonance frequency is directly proportional to the distance between
the slit centre and the postion of the 1st rectangular slot. Addition and position of the second
rectangular slot slightly changes the antenna‟s resonance frequency by few MHz. Besides, it
increases the antenna gain by 1.5 dB and it reduces the level of side lobes by more than 3dB as
will be shown in the next page.
27
Figure 4.8: The effect of the position of 1st rectangualr slot on the antenna’s resonant frequency.
Figure 4.9: The effect of the position of the 2nd rectangualr slot on the antenna’s resonant
frequency.
The proposed antenna has a steerable beam of 15° at the whole antenna‟a operation
bandwidth . The proposed antenna‟s polar far-field radiation pattern at some selected frequencies
are shown in the Figures 4.10. The simulated antenna 3dB beam width is 21˚ at the resonace
frequency with as low as -10.5dB side lobes level.
(a)
(b)
Figure 4.10: Simulated 2D far-field polar coordinate of the proposed antenna radiation pattern.
(a) At resonant frequency (b) At 62.5GHz.
28
Simulation results show that the proposed antenna‟s linear gain equals to 21.7 after
addition of the 1st rectangular slot. Besides, it is enhanced to 28.2 after the 2nd slot addition as
presented in Figure 4.11 and Figure 4.12. Both Figure 4.12 and Figure 4.13 show that the side
lobes level is effectively suppressed after addition of the 2nd rectangular slot. Moreover, it can be
noticed that the addition of the 2nd rectangular slots did not affect the antenna beam‟s steer-ability.
Figure 4.11: The effect of the position of 1st rectangualr slot on the antenna’s radiation pattern.
Figure 4.12: The effect of the position of 2nd rectangualr slot on the antenna’s radiation pattern.
The parametric study of the effect of the width of the rectangular slots on the designed
antenna‟s radiation pattern is shown in Figure 4.13. One can see that the gain of the antenna and
its beam steer-ability is directly proportional to the rectangular slots width. The antenna‟s farfield radiation pattern is simulated for different slots width SW1 of 10mm, 20mm, 30 mm and
40mm as shown in Figure 4.14.
Figure 4.13: The effect of the width of the two rectangular slot on the antenna radiation pattern.
29
The 60 GHz band plasmonic antenna gain performance over its bandwidth after the
addition of both rectangular slots is illustrated in Figure 4.14.
Figure 4.14: the proposed antenna’s simulated gain performance over the operation frequency.
The electric and magnetic field is uniformly distributed over the antenna‟s surface when
there is no rectangular slots as shown in Figure 4.15 (a) and this symmetrical distribution will
make the antenna‟s main beam radiated and concentrated in the zero direction.
(a)
(b)
Figure 4.15: E-field polarization on the proposed antenna surface.
(a) Symmetrical structure with no rectangular slots.
(b) Symmetrical structure with presence of two rectangular slots.
30
Introducing the two rectangular slots will affect the beam steer-ability of the millimetrewave plasmonic antenna because of the asymmetry created in the electric and magnetic fields
distribution on both slit‟s sides as shown in Figure 4.15 (b) and Figure 4.16. Creating slots on one
slit side will make the electric and magnetic fields concentrated on the opposite side, hence
steering the antenna‟s beam to that side.
Figure 4.16: H-field polarization on the proposed antenna with presence of two
rectangular slots.
The proposed antenna‟s surface current is also has symmetrical distribution when the
antenna has no slots as shown in Figure 4.17 (a). Asymmetrical distribution of the surface current
will be created when the two rectangular slots are introduced as clearly shown in Figure 4.17 (b).
In addition, the current density magnitude is increased on the non-slotted side of the antenna as
shown in Figure 4.17(b) .The surface current density increment explains why the antenna‟s beam
becomes steerable and particularly why the gain has dramatically increased by 4.5 dB after the
addition of the two rectangular slots.
(a)
(b)
Figure 4.17: Distribution of the surface current on the proposed antenna. (a) without slots (b)with slots.
31
4.3 Steer the antenna’s beam by introducing three elliptical slots
Experimental results show that the millimetre wave plasmonic antenna‟s beam can be
steered by using slots in the shape of ellipse as shown in figure 4.18. Three elliptical slots are
used to steer the antenna‟s beam and to enhance the antenna‟s gain as well. The antenna‟s beam is
steered by 20˚. This techinque is more powerful in terms of the beam steer-ability compared to
introducing two rectangulr slots which was only capable to steer the beam up to 15˚. The
enhancement of the beam steer-ability was at the cost of gain decrement at resonance frequency.
Figure 4.18: The configuration of the proposed antenna.
The ellipses dimensions are as follows: A =6.5 mm is the ellipse major axis, B = 0.6mm
is the ellipse minor axis, C = 4.6 mm is the horizontal distance between the slit centre and 1st and
2nd ellipse, D = 5.1mm is the vertical distance between the slit‟s centre and the 3rd ellipse and E =
1.85mm is the vertical distance between the slit‟s centre and the 1st and 2nd ellipses. The antenna‟s
linear gain at resonance frequency is 17.9 (12.53 dB) as shown in Figure 4.19.
(a)
(b)
Figure 4.19: Simulated far-field radiation pattern of the proposed antenna.
(a) 3D far-field radiation pattern. (b) 2D polar coordinate.
The proposed antenna resonates at 61.54 GHz with a simulated bandwidth of 2.06GHz
ranging from 60.66 GHz to 62.72 GHz. Adding the ellipses has shifted the resonant frequency
from 62.1 GHz to 61.54 GHz. The effect of the three elliptical slots on the antenna steer-ability is
simillar to the effect of the two rectangular slots introduced in the previous section. Introducing
the lowest two ellipses will affect the antenna‟s resonant frequency and the beam steer-ability to
15˚. Besides, introducing the 3rd ellipse will increase the antenna‟s beam steer-ability to 20˚, gain
and it will highly reduce the side lobes level gain.
32
CHAPTER 5
DIRECTLY COUPLED AND STEERABLE MILLIMETRE WAVE
PLASMONIC ANTENNA
Two different steerable and directly coupled plasmonic antenna structures will be
presented in this chapter. The first antenna design is based on slit grating structure that has been
discussed in the previous two chapters; meanwhile, the second design is based on Bull‟s eye
structure. Both antenna structures are designed to work at the 60GHz band. Both suggested
structures achieve much higher gain with an excellent steerable beam than the previously
proposed antennas. The electromagnetic energy will be coupled to both plasmonic antennas by
using rectangular and circular waveguides, instead of normal coupling that uses the patch
antenna.
The plasmonic antenna beam will be steered and manipulated in the proposed designs by using
two different techniques. The first technique is to introduce slots on any slit‟s side to steer the
beam to the opposite side, while the second technique is to change the slit position to manipulate
the electric field and magnetic field distribution on the antenna‟s surface to steer the beam.
5.1 Directly coupled and steerable slit grating millimetre-wave plasmonic antenna
design
5.1.1 Directly coupled slit grating millimetre-wave plasmonic antenna design
The proposed slit grating antenna which is shown in Figure 5.1 has optimized dimensions
quite similar to the plasmonic antenna fed by patch antenna that was shown in section 3.32. The
antenna‟s dimensions are elaborated in Table 5.1. The proposed antenna resonates at 62 GHz with
a bandwidth of 8.35 GHz. The electromagnetic energy is coupled to the plasmonic antenna by
using rectangular waveguide which operates on the
mode. Using a wave guide to couple the
electromagnetic energy to the plasmonic enhances the antenna gain at resonance frequency by 4
dB to reach 14.7 at 62GHz. However, the same structure achieved only 10dB of gain when the
coupling is achieved by using patch antenna.
Figure 5.1: The slit grating antenna geometry. (a) Front view (b) Top view.
33
Table 5.1: The slit grating antenna parameters and specifications
Dimension of the whole Geometry W
20 mm
L=
Wave guide dimensions a
41 mm.
1.3mm
b
y = 3.2mm
4.5 mm
Groove‟s width GW = 0.3 mm.
Groove‟s depth Gd = 0.95 mm.
Groove‟s period P = 4.4 mm.
Distance between slit and 1st groove A = 1.1 mm.
Dimension of the slit SL
Thickness of the Plasmonic antenna T = 1.2mm.
SW = 0.6 2.35 mm.
The proposed antenna operates on a range of frequencies between 60.83GHz and 69 GHz
as shown in figure 5.2. In addition, the antenna has a linear gain of 29.4 (14.7dB) with a 3dB
angular width of 32.1˚ at 62GHz as shown in Figure 5.3. The antenna‟s maximum gain is 15.4 dB
at 61 GHz and the antenna‟s gain performance over the antenna‟s operation bandwidth is
illustrated in Figure 5.4. Complete comparison between the antenna that was fed by patch that
was designed in section 3.42 and the directly coupled antenna is elaborated in Table 5.2.
Figure 5.2: Simulated 𝑺𝟏𝟏 parameter of the proposed slit grating plasmonic antenna.
(a)
(b)
Figure 5.3: The simulated far-field radiation pattern of the proposed antenna. (a) 2D
polar coordinates. (b) 3D radiation pattern.
34
Figure 5.4: The slit grating antenna’s simulated gain over
the operation bandwidth.
Table 5.2: The proposed antenna’s performance with different feeding methods
Type of the
feeding
Resonant
frequency
(GHz)
Bandwidth
(GHz)
Simulated
gain at
resonance
(linear)
Simulated
gain at
resonance
(dB)
Minimum
return loss
( )
(dB)
3dB
Beam
width
Side
lobe
level
(dB)
Fed by
patch
62.2
2.47
11.1
10.45
-24.68 dB
31.8˚
-7.6
Fed by
Waveguide
62.1
8.35
29.4
14.7
-28.45
32.1˚
-7
One of the main advantages of the designed antenna is that the bandwidth and the gain of
the antenna can easily be controlled by changing the antenna‟s main parameters. The antenna‟s
bandwidth can be varied between 500 MHz and 10GHz by manipulating the slit dimensions. It
has been found that the antenna‟s bandwidth is directly proportional to the slit width, while the
antenna‟s resonance frequency is inversely proportional to the slit length.
The grooves width GW, distance between the 1st groove and slit A and groove‟s period P
dimensions have major effect on the antenna‟s radiation pattern and gain characteristics with no
major effect on the antenna bandwidth and resonance frequency. Moreover, the position and
width of the 1st groove has minor effect on the antenna‟s bandwidth and resonance frequency.
Thus, with a constant distance of A „distance between the slit and the 1st groove‟, the antenna‟s
bandwidth and resonance frequency can be controlled easily by changing the slit width and
length.
35
5.1.2 Steer the antenna’s beam by introducing two identical rectangular slots
Introducing two rectangular slots as shown in Figure 5.5 will steer the antenna beam by
20˚ on the entire operation frequencies. The electromagnatic energy is coupled to the antenna
using rectangular waveguide that has the same dimensions as the one that has been used in the
antenna presented in section 5.1.1. Furthermore, the proposed antenna dimensions are identical to
the antenna‟s dimensions that were presented in section 5.1.1. Introducing the two rectangular
slots does not only steer the antenna‟s beam, but it also increases the antenna‟s gain at resonance
frequency by 2 dB.
Figure 5.5: The geometry of the proposed antenna, X1 = 1.5mm, X2=2.9mm, E=0.55mm,
S=40mm, SW=2.35mm, SL=0.2mm.
The proposed antenna has a bandwidth of 2.9 GHz and resonates at 63 GHz as shown in
figure 5.6. The antenna‟s beam is steered by 20˚ with a simulated gain of 42.49 (16.3 dB) at
resonance frequency as shown in Figure 5.7.
Figure 5.6: Simulated
parameter of the proposed antenna.
36
(b)
(a)
(d)
(c)
Figure 5.7: The simulated far-field radiation pattern of the proposed antenna design at
resonance frequency. (a) 3D radiation pattern. (b) 3D radiation pattern. (c) 2D polar
coordinates.
The antenna gain performance against the antenna‟s bandwidth is shown in Figure 5.8.
Besides, the antenna‟s surface current density is presented in Figure 5.9. It can be seen that the
asymmetric current density created by the rectangular slots as shown in Figure 5.9 will steer the
antenna beam in a same manner as disscussed in section 4.2.
Figure 5.8: The steerable slit grating antenna’s simulated gain over the operation bandwidth.
37
Figure 5.9: The proposed antenna surface current density at resonance frequency.
38
5.2 Bull’s eye millimetre-wave plasmonic antenna with rectangular slit
The proposed Bull‟s eye plasmonic antenna is shown in Figure 5.13. The antenna has
optimized dimensions that are shown in table 5.3. The suggested antenna resonates at 63GHz
with a bandwidth of 9.346GHz as shown in figure 5.14.
Figure 5.13: Bull Eye millimetre wave antenna. (a) Front view (b) Top view.
Table 5.3: The Bull’s eye plasmonic antenna parameters and specifications
Dimension of the whole Geometry W
= 34mm
W
Dimension of the slit SL
34mm.
SW =
0.8 mm 2.4 mm.
Distance between slit and 1st groove A =
Wave guide dimensions a
4.5 mm.
1.8mm
b
Y = 3.2 mm
4.5mm.
Groove‟s depth Gd = 0.94 mm.
Groove‟s width GW = 0.15 mm
Groove‟s period P = 4 mm.
Thickness of the antenna T = 1.2 mm.
Figure 5.14: Simulated
parameter of the proposed Bull’s eye antenna.
39
The designed Bull‟s eye antenna gain at resonance frequency is 24.1 in linear (13.82 dB)
as shown in Figure 5.15. The proposed antenna‟s gain performance over its bandwidth is
illustrated in Figure 5.16.
(b)
(a)
Figure 5.15: The simulated far-field pattern of the Bull Eye antenna at resonance frequency.
(a) 3D radiation pattern. (b) 2D polar coordinates.
Figure 5.16: The Bull Eye antenna gain performance over the entire operation bandwidth.
The Bull‟s eye antenna bandwidth can be manipulated in a similar manner to the slit
grating structure bandwidth. The slit‟s width is directly proportional to the antenna‟s bandwidth,
while the antenna‟s resonance frequency is inversely proportional to the slit length.
Similarly to the slit grating structure, simulation results shows that the antenna‟s radiation
pattern is a function of groove‟s width GW, groove‟s period P, groove‟s depth Gd and distance
between the 1st groove and slit A. Hence, to maximize the antenna‟s far-field performance each
parameter should be optimized carefully.
40
5.4 Bull’s eye millimetre-wave plasmonic antenna with circular slit
Coupling the electromagnetic energy to the Bull‟s eye antenna by using circular
waveguide and circular slit as shown in 5.19 will immensely enhance the antenna‟s impedance
bandwidth to be more than 350%. The suggested Bull‟s eye antenna has an endless bandwidth of
more than 243 GHz ranging from 57.43GHz to 300 GHz as shown in figure 5.20. Besides, the
antenna has a very good simulated gain performance over the entire bandwidth as shown in figure
5.21.
Figure 5.19: Top view of the proposed Bull’s eye antenna with circular slit.
Table 5.4: The proposed antenna parameters and specifications
Dimension of the antenna W
radius of the slit r = 1.6 mm.
W = 1.6mm.
Groove‟s width GW = 0.16 mm.
Groove‟s depth Gd = 0.94 mm.
Groove‟s period P = 4.5 mm.
Thickness of the antenna T = 1.2 mm.
Waveguide dimensions r
Distance between slit and 1st groove A =
Y =
4.072 mm.
1.6mm 5mm.
Figure 5.20: Simulated
parameter of the proposed plasmonic antenna between 57GHz
and 300GHz.
41
The Bull‟s eye with circular slit antenna‟s gain performance between 60 GHz and 70GHz
is quite similar to the performance when the slit has rectangular shape as shown in figure 5.21.
The antenna has a gain of 13.7 dB at first resonance which is 64 GHz. However, the Bull‟s eye
with circular slit gain drops to minimum of 7dB at 75GHz, then it starts to rise steadily as the
frequency increases to hit 19.5 dB on 300 GHz as shown in figure 5.22. The antenna
parameter‟s performance between 60 GHz and 70 GHz is presented in figure 5.23.
Figure 5.21: The proposed antenna’s gain performance between 60GHz and 70GHz.
Figure 5.22: The proposed antenna’s gain performance between 57 GHz and 300GHz.
Figure 5.23: Simulated
parameter of the proposed Bull’s eye antenna
between 57GHz and 300GHz.
42
(a)
(b)
(c)
(d)
(e)
(f)
Figure 5.24: The far-field radiation pattern of the Bull’s eye millimetre-wave plasmonic antenna
with circular slit at some selected frequencies.(a) 3D at 90 GHz. (b) 2D at 90 GHz.
(c) 3D at 200 GHz. (d) 2D at 200 GHz. (e) 3D at 300 GHz. (f) 2D at 300 GHz.
43
Table 5.5 demonstrates a comparison between the performance of the slit grating antenna,
Bull‟s eye with rectangular slit and Bull‟s eye with circular slit. One can see that the three
antennas have similar gain performance at the resonant frequency, but the Bull‟s eye antenna with
rectangular slit has much lower 3dB beam width than the other two proposed antennas. Besides,
Bull‟s eye antennas have lower side lobe level than the slit grating antenna. Moreover,both slit
grating and Bull‟s eye have similar bandwidth when the slit is rectangular and the feeding is
provided by rectangular waveguide, but when the feeding is provided by circular waveguide with
circular slit the antenna‟s bandwidth increases dramatically by more than 200 GHz.
Table 5.5: Comparison between the slit grating and Bull’s eye millimetre-wave plasmonic
antennas
Type of the
antenna
Resonant
freque
-ncy
(GHz)
Bandwidth
(GHz)
Simulated
gain at
resonance
(linear)
Simulated
gain at
resonance
(dB)
Minimum
return
loss ( )
(dB)
3dB
Beam
width
Side
lobe
level
(dB)
Slit grating
62.1
8.35
29.4
14.7
-28.45
32.1˚
-7
Bull‟s eye with
rectangular slit
Bull‟s eye with
circular slit
63
9.346
24.1
13.82
-27.8
11.5 ˚
-9.7
64
243
23.5
13.7
-20.9
24˚
-8.6
44
CHAPTER 6
CONCLUSIONS AND FUTURE WORK
6.1 Conclusions
This research has portrayed novel designs of steerable millimetre-wave plasmonic
antennas by controlling and directing radiation at metal surfaces through spoof surface plasmons
phenomenon. The proposed antennas characteristics were investigated with various options and
were found to operate satisfactory. The designed antennas have excellent beam steer-ability with
very high gain performance over the operation bandwidth. The proposed steerable millimetre
wave plasmonic antennas presented in this research were based on the two common structures
which are: Slit grating structure and Bull‟s eye structures.
Two different Slit grating plasmonic antennas resonate on 12 GHz and at the 60 GHz
band were designed and were successfully simulated. The two Slit grating plasmonic antennas
were simply realised by putting structured metal surface in the near field on top of simple
rectangular patch antenna. Placing a structured metal (plasmonic antenna) on top of the patch that
resonates at 12 GHz has enhanced the antenna‟s gain by 8.3 dB; meanwhile, placing a structured
metal on top of the patch that resonates on the 60 GHz band has enhanced the antenna‟s gain by
4.6 dB.
An investigation to steer the slit grating plasmonic antenna that was fed by patch antenna
which operates at the 60 GHz has been carried out. It has been found that introducing slots on the
plasmonic surface in certain patterns will steer the antenna‟s beam. For example, introducing two
slots in shape of crosses on the antenna‟s surface has steered the slit grating millimetre-wave
plasmonic antenna by 10˚. Furthermore, it has been found that introducing two rectangular slots
has steered the antenna‟s beam by 15˚.
It has been proved that coupling the electromagnetic energy to the slit grating millimetrewave plasmonic antenna by using rectangular waveguide has increased the antenna‟s gain by 4.3
dB to reach 14.7 dB. Besides, a simulated gain of 16.3 dB and steerable beam of 20˚ are obtained
when the electromagnetic energy is coupled by a rectangular waveguide to the steerable slit
grating plasmonic antenna with two rectangular slots. The proposed novel steerable slit grating
millimetre-wave plasmonic antenna by introducing slots on the antenna‟s surface is believed to be
the first break through of this research.
Two millimetre-wave Bull‟s eye plasmonic antennas were some of the fruitful outcomes
of this work. The two Bull‟s eye antennas were successfully designed to operate at the 60GHz
band with high gain. In addition, it has been demonstrated that changing the Bull‟s eye slit shape
and the feeding technique will improve the antenna‟s bandwidth tremendously. For instance, an
impedance bandwidth of more than 350% was achieved when the Bull‟s eye millimetre-wave
45
plasmonic antenna slit shape and feeding waveguide was changed from rectangular to circular.
An achievement of 350% of impedance bandwidth using the Bull‟s eye structure which is used to
have narrow impedance bandwidth prior to this research is believed to be the second
breakthrough of this study.
6.2 Recommendations for future work
The plasmonic antennas beam were steered in this study by two different methods which
are introducing slots on the surface of plasmonic antenna and changing the slit‟s position;
meanwhile, further investigation of the possibility of integrating those techniques with other
current techniques used to steer the plasmonic antenna to enhance the antenna steer-ability is
essential.
Bull‟s eye millimetre-wave plasmonic antenna with circular slits and other antennas that
presented in this work can be further studied and modelled to support THz communication.
Finally, fabrication of the designed antennas is necessarily to validate the simulated results.
46
REFERENCES
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Boosting and Energy Savings in Wireless Ad-hoc Networks. In: High-Capacity Optical Networks
and Enabling Technologies (HONET); 2010 Dec 19-21; Cairo, Egypt. P. 91-95. Available from:
IEEE Xplore.
[2] Kasch, Burbank J.L and Andrusenko J. The Effects of Antenna Pointing Error on Bit Error
Rate Performance in Mobile Directional Antenna Applications. In: CCECE „06; 2006 May;
Ontario, Canada. P 1652 – 1657. Available from: IEEE Xplore.
[3] 1. Amin M. Abbosh. (2008). Directive antenna for ultra wideband medical imaging Systems
International Journal of Antennas and Propagation. Volume 2008.
[4] T. D. James, Z. Q. Teo, D. E. Gómez, T. J. Davis and A. Roberts .The plasmonic J-pole
antenna. Applied Physics Letter. 2013; 102:033106.
[5] Firdaus M, Zhirun Hu and Abdalla M A. Ultra high gain of plasmonic inspired antenna and
its beam forming. Antennas and Propagation Conference (LAPC); 2012 Nov 12-13.
Loughborough, UK. Available from: IEEE Xplore.
[6] Haofei Shi, Xingzhan Wei, Zeyu Zhao, XiaochunDong,Yueguang Lu, and Chunlei Du, “A
new surface wave antenna based spoof surface plasmon mechanism”, Microwave AndOptical
Technology Letters, October 2010, 52:10.
[7] Beruete, M Campillo , Dolado J.S, Rodriguez-Seco, Perea E, Falcone F and Sorolla M. Very
low-profile “Bull’s Eye” feeder antenna. Antennas and Wireless Propagation Letters, IEEE.2005;
4: 365 – 368.
[8] William L. Barnes, Alain Dereux & Thomas W Ebbesen. Surface plasmon subwavelength
optics. Nature. 2003; 424: 824-830
[9] J.B. Pendry, L Martı´n-Moreno, and F.J. Garcia-Vidal, “Mimicking surface plasmons with
structured surfaces”, Science, August 2005, 305:847.
[10] Zhichao Ruan and Min Qiu, (2007). Slow electromagnetic wave guided in subwavelength
region along one dimensional periodically structured metal surface. Applied physics letter. 90,
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[11]Guangyuan Li, Feng Xiao, Li Kun, Alameh K and Anshi Xu. Theory, Figures of Merit, and
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Surface Corrugations. IEEE. 2012m, 30 (Issue: 15): 2405 – 2414.
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(ECTC), 2012 June 1 2012; San Diego, CA. p. 1846 – 1851. Available from: IEEE Xplore
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(ECTC), 2012 June 1 2012; San Diego, CA. p. 1846 – 1851. Available from: IEEE Xplore.
[14] M. Beruete, I. Campillo, J. S. Dolado, J. E. Rodríguez-Seco, E. Perea, F. Falcone. LowProfile Corrugated Feeder Antenna. IEEE Antennas and Wireless Propagation Letters.2005, Vol.
4: 378 – 380.
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[15] Zhao Zeyo, Huang cheng , Fen Qin and Luo Xiangang. Application of subwavelength
corrugated grooves in the antenna field. In: Asia Pasific Microwave Conference (APMC); 2009
Dec 7-10; Singapore. P. 1792 – 1795. Available from: IEEE Xplore.
[16] Cheng Huang , Zeyu Zhao and Xiangang Luo. A Highly Directive Slot Antenna with
Dielectric Loaded Corrugated Structure. In: International symposium on antenna and propagation
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48
APPENDIX A
CLAIM OF POSSIBLE PUBLICATION
The dissertation author and the project supervisor believe that the results that were
presented in this study worth to be published in two research papers which one of them at least is
a journal. We believe that the first publication will be based on the results of the steerable
millimetre-wave slit grating antennas that were presented in section 4.2 and section 5.2 and it is
expected to be submitted within two week time after the dissertation submission deadline to IET
Microwave, Antennas & propagation journal. After that, another research paper will be written
based on the Bull‟s eye millimetre-wave plasmonic antenna with circular slit that has very
broadband bandwidth.
49
APPENDIX B
RECTANGULAR PATCH ANTENNA DESIGN
A rectangular patch antenna is designed based on the transmission line model. The patch width
has a minor effect on the resonant frequency and major effect on the antenna‟s bandwidth and
radiation patterns. However, the Patch length controls the resonant frequency. The design
methodology for a patch antenna based on transmission line model is as following [21]:
A. Calculation Of The Width And Length Of The Rectangular Patch.
Step 1: Calculation of the Width (W)
√
Where, c is velocity of light,
is the resonant frequency and
is the dielectric constant.
Step 2: Calculating the Length (L)
To calculate the length of the patch, the effective dielectric constant
) should first be
calculated. As the frequency of operation increases the effective dielectric constant approaches
the value of the dielectric constant of the substrate is given by:
(
=
)
(
=
for
)
Then , the actual length is given by the following equation :
√
√
–2
√
(3)
50
(1)
[
√
] for
(2)
APPENDIX C
FEASIBILITY STUDY REPORT
Course: MSc. Communication System Engineering.
Unit: Feasibility Study.
Project Title: On the Study of High Gain and Steerable
Millimetre-Wave Plasmonic Antenna.
Name: Shaker M.M Alkaraki.
Student ID: 8437837
Project Supervisor: Dr. Zahirun Hu.
Date: 10th May 2013
51
ABSTRACT
56
CHAPTER 1: INTRODUCTION
57
1.1 Background
57
CHAPTER 2: LITERATURE
60
2.1 Previous Studies On Spoof Plasmonic Antennas
60
2.3 Direct Coupling And Beam Steering Possibility Of Millimetre Plasmonic Antenna 62
CHAPTER 3: METHODOLOGY
65
3.1 Background
65
3.2 Preliminary Antenna Design
66
CHAPTER 4: PROJECT PLANNING AND REVIEW OF PROJECT RISK
69
4.1 Project Planning And Milestone Chart
69
4.2 Project Risk
70
REFERENCES
71
APPENDIX A: RISK ASSESSMENT
72
APPENDIX B: RECTANGULAR PATCH ANTENNA DESIGN
76
54
LIST OF FIGURES
Figure 1.1: Spoof SPs between metal and dilectric material at Metal interface.
Figure 1.2: Metal surface with slit smaller than the incident wave.
Figure 2.1: Plasmonic strucures composed of subwavelength apertures. (a) Bull‟s eye structure
(b) slit- grating structure.
Figure 2.2: Slit grating THz plasmonic antenna.
Figure 2.3:Bull‟s Eye THz plasmonic antenna.
Figure 2.4: (a) 1 D Periodic corrugated Structure ;(b) Spoof plasmon structure with
subwavelength minor grooves in the surface.
is the major groove‟s period,
is the major
groove‟s width and is the major groove‟s depth .
Figure 2.5: Farfield radiation in Polar coordinates at 9.0 GHz and 12.0 GHz.
Figure 2.6: Geometry of the corrugated directive slot antenna, (a) Top view; (b) Side view.
P=11.8mm, P1=9.1mm,w=2.4mm,d=2.7mm,t=1.5mm.
Figure 2.7: Electric field distribution of the slot antenna.
Figure 2.8: (a) top view of the Bull‟s Eye Antenna (b) cross section of the antenna with
parameters =12mm, =11.54mm, =17mm, =10mm and
=3.4mm
Figure 2.10: Polar coordinate representation of far-field gain radiation
pattern for non-symmetrical structure.
Figure2.9: Non-Symmetreical Steerable Plasmonic Antenna.
Figure 3.1: Steps illustrates the methodology followed in the project.
Figure 3.1 : Rectangular Patch antenna Simulated 3D Farfield radiation pattern
Figure 3.2: Millimetre wave plasmonic antenna fed by rectangular patch
Figure 3.3:
of the proposed plasmonic antenna.
Figure 3.4: Farfield Radiation pattern of the proposed plasmonic antenna. (a) 3D Farfield Pattern
(b) Polar coordinate representation
55
Abstract
Many Millimetre wave applications require the design of directive and steerable beam antennas.
Recently, plasmonic antenna have shown promising characteristics that makes it an impressive
future alternative of phased array antenna for millimetre-wave applications. Plasmonic antennas
have the capability to produce directive beam as efficient as array antennas with lower cost and
less design complexity. Millimetre-wave plasmonic exploits the surface plasmons(SPs)
phenomenon to enable the incidents electromagnetic wave to be confined into dimensions smaller
than the wavelength. Surface plasmons localizes the incident wave to the antenna metallic surface
and redirect them to produce highly directive beam. It has been shown that introducing
corrugation structures on the metallic antenna surface will enable SPs to produce directive and
steerable beam. However, this report provides the outline and introduction for the dissertation
project which will be detailed study and design high gain and beam steerable millimetre-wave
plasmonic antenna through parametric simulation using CST microwave studio software. Finally,
an initial Millimetre plasmonic antenna based on existing designs operates at 12GHz with a gain
of 13.51Db has been developed and simulated in this report.
56
Chapter 1
Introduction
1.1 Background
Wireless communication systems depend on the transmission of information through
electromagnetic waves. The coupling between electronic circuits and these electromagnetic waves
is achieved by antennas. Thus, proper antenna design would not only enhance the reliability of the
wireless communication systems but would reduce the cost as well.
However, as wireless
technology industry evolves, millimetre and microwave applications have rapidly grown to
satisfy the need of this industry.
Millimetre Directive antennas is widely deployed in wireless ad hoc network to increase the
system capacity and to save energy. The use of such antennas will not only enhance the network
throughput, but it will reduce energy dissipation as well [1]. Directive antennas have shown an
impressive capabilities in boosting link capacity, enhancing security through decreasing
accessibility and boosting bandwidth efficiency through spatial diversity in both military and civil
mobile networks[2].
Besides , design of millimetre steerable directive
antenna is crucial
requirement in the design of radar and imaging systems and such antennas that have high gain
and steerable beam capabilities is essential.
The main target of any antenna, whether operating in radio frequencies (RF) or optical
frequencies is to radiate and receive electromagnetic energy. Thus, well known optical antennas
design concepts and procedures can be investigated to be used to design RF antennas and
particularly rapidly merging millimetre wave antennas [3]. Plasmonic antennas have been firstly
proposed for optical applications and it utilizes plasmonic surface waves to redirect the
electromagnetic waves to produce directive beam.
The promising characteristics of plasmatic antenna make it an impressive future alternative of
phased array antenna for millimetre-wave applications. Plasmonic antennas have the capability to
produce directive beam as efficient as array antennas with lower cost and less design complexity.
However, the beam steerability of plasmonic antennas is still one of the main challenges in the
current antenna designs.
Recently, scientist have shown great interest in surface plasmons (SPs), because it explores how
electromagnetic fields can be confined in dimensions that is much smaller than the wavelength.
57
Metals such as silver and copper support surface plasmons which are electromagnetic surface
waves that propagate on the surface of a metal and dielectric as shown in figure 1.1 .These waves
are localized near the surface and originate from the free electrons of the metal. Surface plasmons
have shown potential applications recently in subwavelength optics, biophotonics, microscopy,
optical antennas and biological sensors [4][5].
Figure 1.1: Spoof SPs between metal and dielectric material at Metal interface[4].
Usually electromagnetic waves cannot propagate into dimensions that are smaller than the
wavelength due to diffraction limit. For example, electromagnetic wave will not be confined into
slit shown in figure 1.2 if the width of the slit is smaller than the incident wave [6].
Figure 1.2: Metal surface with slit smaller than the incident wave[6]
58
However, the localization of incident wave to the metal surface shown in figure 1.2 can be
controlled by introducing corrugated structures that enable the incident waves to be guided and
confined into the slit that has dimensions much smaller than the incident wavelength, due to
surface plasmons. Besides, It has been demonstrated that periodic corrugation in metal surface
will increase the momentum associated with surface plasmon and will enhance the directivity of
the radiated beam due to surface plasmon constructive interference.
The aim of this project is to study and investigate high gain and steerability of millimeter-wave
antennas by controlling and directing radiation at metal surfaces through spoof surface plasmons
phenomenon. The main objectives of the project are outlined as follows:

To understand the basic concept of „spoof‟ surface plasmon.

To practice and familiar with CST Microwave Studio simulation tool

To design and simulate Bull‟s Eye or other types of plasmonic millimeter-wave antennas.

To perform parametric simulation to analyze the performance of beam steering capability
of plasmonic antennas.

To investigate the coupling mechanism between the launching antenna and plasmonic
one.

To investigate the possibility of direct coupling from the circuit or waveguide to the
plasmonic antenna.
59
Chapter 2
Literature Review
One of the interesting SPs applications is the plasmonic antennas which has a great capability of
extreme light and electromagnetic beam concentration. Among these antennas, structures that
consist of subwavelength apertures flanked by surface corrugations which called as two
dimensional slit-grating structure and three dimensional bull‟s eye structure as shown in figure
2[7].
Figure 2.1: Plasmonic structures composed of subwavelength apertures. (a) Bull’s eye structure (b)
slit- grating structure[7].
The above suggested corrugated structures have a great capability to improve the transmission of
electromagnetic waves at microwave and optical frequencies due to constructive interference of
resonating plasmonic modes. Besides, these modes can be manipulated by changing the structure
parameters such as period and depth of the grooves. The grooves have the ability to redirect
incident waves to the subwavelength apertures through exciting surface wave in the form of
surface plasmons. Then these waves are refocused by the aperture and the transmission is
extremely being enhanced [8]. Nevertheless, this approach is well known in design of optical and
THz high gain antennas but recently was implemented to design high gain millimetre microwave
antennas.
2.1 Previous studies on spoof plasmonic antennas
Few studies are available on Plasmonic antennas for millimetre waves. However, several studies
have conducted on plasmonic antennas for optical and THz applications, one of those studies
suggested two antennas for beam shaping of Terahertz quantum cascade lasers. The proposed
antennas operate at frequency of 3 THz and with simulated gain of 16 dBi and 21 dBi
respectively. Both antennas are shown in figure 2.2 and 2.3[9].
60
Figure 2.2: Slit grating THz plasmonic antenna[9]. Figure 2.3:Bull’s Eye THz plasmonic antenna[9].
Haofei et al. has employed spoof surface plasmons phenomenon to design an antenna operates
from 8.2 to 12.5 GHz and he has verified the role of spoof surface plasmon by introducing minor
sub-wavelength
grooves of period smaller than 1/10th of the operation wavelength. In the
designed antenna shown in figure 2.4, the feed source is converted into radiated wave via the
corrugated structure and the antenna‟s farfield properties depends on the diffraction of surface
waves[10].
Figure 2.4: (a) 1 D Periodic corrugated Structure ;(b) Spoof plasmon structure with subwavelength
minor grooves in the surface.
is the major groove’s period,
is the major groove’s width and is
the major groove’s depth [10].
The giving two expressions represent the farfield scattering properties of the given grating
structure:
(2.1)
(2.2)
61
Where
is the wave vector of the incident wave,
vecto of surface wave and in this case ,
is the diffraction angle,
, and
is the wave
are the diffraction orders on each
side. However, according to the author, the radiated enegy is going to be concentrated and
maximized when the condition
is met, because the diffraction order from both
sides will have the same divergence angle. Finally, the simulated farfield radiation patten for the
proposed antenna based on the following dimensions,
=30mm,
=5mm , =4.5mm, =1.2mm
and =2.38mm, is presented in figure 2.5.
Figure 2.5: Farfield radiation in Polar coordinates at 9.0 GHz and 12.0 GHz[10].
2.3 Direct coupling and Beam Steering possibility of Millimetre plasmonic antenna
A microwave scaled millimetre wave version of optical plasmonic antennas has driven new
potential applications recently. Many studies have used a launching antenna to couple
electromagnetic energy into the plasmonic antenna. Nevertheless, on study has proposed a highly
directive slot antenna with dielectric loaded corrugated structure similar to slit- grating structure
previously shown in figure 2. The proposed antenna has symmetrical periodic grating (grooves)
on dual side of the slot and the slot is directly fed by a waveguide as exciting source. A dielectric
layer with high dielectric constant ( =9.8) is loaded between neighbouring grating to reduce the
antenna apertures. The proposed antenna is shown in figure 2.6 and has a gain of 18.1dBi at
frequencyof14.5GHz[11].
Figure 2.6: Geometry of the corrugated directive slot antenna, (a) Top view; (b) Side view.
P=11.8mm, P1=9.1mm,w=2.4mm,d=2.7mm,t=1.5mm[11].
62
The improvement mechanism in the antenna directivity is due to constructive superposition of
secondary sources radiated from the main source and dielectric layer from the slot antenna. For
optimal results the grating period P should be approximately closed to the wavelength and the
dielectric thickness t is 1.5mm[11]. The electric field distribution of the proposed antenna is
illustrated in figure 2.7.
Figure 2.7: Electric field distribution of the slot antenna [11].
Another study has proposed a miliimetre Bull‟s Eye corrugated antenna directly fed by a wave
guide feeder. The proposed antenna is presented in figure 9 and it has two resonant frequencies at
16GHz and 12 with a gain of 15dBi at 16GHz [12].
Figure 2.8: (a) top view of the Bull’s Eye Antenna (b) cross section of the antenna with parameters
=12mm, =11.54mm, =17mm, =10mm and
=3.4mm[12].
The author reported that the slit‟s depth ,h=12mm, determines the longitudinal resonant frequency
of the antenna at 16GHz, while the lower resonant frequency at 12GHz is determined by the slit
width. The width of every grating and the grating period
control the angle where plasmonic
like constructive interference take place, hence both controls the antenna‟s gain. Finally, the
author demonstrated practically the same non corrugated flat metallic structure has very low gain
with nearly isotropic radiation pattern.
63
Firdaus et al. has shown that the plasmonic antenna beam pattern can be controlled such that the
antenna become steerable by designing non symmetrical corrugated structure as shown in figure
2.9. The proposed plasmonic antenna resonates at 9GHz with linear gain of 14.1 as shown in
figure 2.10[6].
Figure2.9: Non-Symmetreical Steerable Plasmonic Antenna[6]
Figure 2.10: Polar coordinate representation of far-field gain radiation
pattern for non-symmetrical structure[6].
In the proposed design, the electromagnetic radiation will be concentrated in the non-symmetrical
side of the antenna because of the effect of spoof surface plasmon and will focus the radiated
beam towards that direction.
64
Chapter 3
Methodology
3.1 Background
To accomplish the aim and objectives of this study, millimetre steerable plasmonic antenna needs
to be successfully modelled, designed and simulated. The CST Microwave Studio Software
package is going to be used to evaluate and test the performance of the suggested antenna. CST is
powerful software that enables antenna engineer to simulate antenna performance and various
antenna parameters such as: return loss (
), directivity, gain and radiation patterns. Then,
parametric study is going to be conducted to evaluate the effect of different antenna parameters
on the proposed design using optimization and sweep facilities provided by CST. The following
steps summarize the methodology of this study:
i.
Literature Review
Throughout this research, an extensive study is conducted to understand the theory of surface
plasmon radiation and physics behind plasmonic antenna. A further comprehensive investigations
need to be conducted to understand the capability of spoof plasmonic antenna to guide and
support highly directive and steerable beam. For instance, studies presented in [4] and [5] explain
how surface plasmon waves are generated by altering the structure of metals. However, studies
presented in [10] ,[11] and [12] illustrate how surface plasmon waves are used to design highly
directive millimetre antennas, besides, [10] provides some mathematical analysis that helps in the
design of millimetre wave antennas.
ii.
Preliminary Antenna Design
An existing design for spoof plasmonic antenna based on [6], [10] and [12] will be first simulated
by using CST and this involves design of Bull‟s eye structure and slit grating structure. Then, this
design will be used as a reference to develop a novel millimetre steerable plasmonic antenna.
However, at this stage simple slit grating structure millimetre wave plasmonic antenna fed by
rectangular patch antenna have been designed to operate at 12GHz and at subsequent stages
Bull‟s eye structure will be modelled and designed to achieve the aim of this study.
iii.
Enhancing and optimizing the preliminary design
Further optimization on structures, Bull‟s Eye and Slit grating, need to be done to achieve best
possible directivity and bandwidth. Optimization will be done through extensive parametric study
for antenna parameters such as:
g. Metal thickness of the plasmonic antenna.
65
h. Distance between the coupling patch and the plasmonic antenna.
i.
Depth and width of each groove.
j.
Groove‟s number and period.
k. Slit dimensions and slit
shape, for instance, try to simulate the effect of
changing slit shape on the antenna characteristics by simulating different slit
shapes such as circular and elliptical.
iv.
Steerable Antenna Design
Investigation of the beam steerability of the designed plasmonic antenna needs to done at this
stage. Investigations and parametric simulation will be performed on both designed antennas to
achieve beam steerability. The beam pattern of plasmonic antenna can be changed by
designing non-symmetrical corrugated structure so that the beam becomes steerable.
However, few and limited literature is available on the steerability of the millimetre wave
plasmonic antennas, therefore, an extensive efforts to accomplish the steerable antenna
design are needed at this stage.
v.
Investigate the possibility of direct coupling between the antenna and the excitation
source
The final stage of plasmonic antenna design is to investigate the possibility of achieving direct
coupling between plasmonic antenna and feeding method. A patch antenna will be used to couple
energy to plasmonic antenna in the initial proposed design. However, at advance stage the
possibility of direct feeding from transmission circuit or other feeding method such as using wave
guide will be studied and simulated. A summary of the methodology of this project is provided in
figure 3.1.
comprehensive
litreture
review
Preliminary
antenna design
Enhancing and
optimizing the
Preliminary
design
Steerable
plasmonic
antenna design
directly
coupled
plasmonic
antenna
design
Figure 3.1: Steps illustrates the methodology followed in the project .
3.2 Preliminary Antenna Design
The first step of the plasmonic antenna design is to build a similar antenna structure to the one
that presented by Firdaus et al and Haofei et al and in [6] and [10]. The purposes to build such a
66
structure are: to investigate and understand the basic characteristics of Millimetre plasmonic
antenna and most importantly to familiarize myself with the CST software and learn its features
which will enable me to accomplish the aim and objectives of this research according to the
project plan that provided in the following chapter. This basic structure that simulated in this
section will be the foundation of the final design that will be presented later on in the dissertation.
The resonant frequency of the designed antenna is chosen to be 12GHz and a patch antenna is
designed to couple the electromagnetic energy into the plasmonic antenna. The patch antenna can
be placed in the near field or in the farfield of the plasmonic antenna[6]. However, the distance
between plasmonic and the patch antenna is chosen to be 3.9mm ( /6) .The designed patch
antenna is illustrated in figure 10 and detailed design procedure and results are available in
appendix B. The proposed patch antenna has bandwidth of 430MHz and has a gain of 3.88 (5.89
Db) at 12GHz as shown in figure 3.1.
Figure 3.1: Rectangular Patch antenna Simulated 3D Farfield radiation pattern.
Next, the designed patch antenna is used to couple electromagnetic energy into the plasmonic
antenna as shown in figure 3.2 and the geometrical dimensions of the designed antenna structure
are tabulated in table 3.1.
Figure 3.2: Millimetre wave plasmonic antenna fed by rectangular patch
67
Table 3.1: Dimensions of the proposed antenna
Groove‟s width = 5mm
Dimension of the whole Geometry =
240 mm 100mm
Dimension of the slit =
Groove‟s period =
Groove‟s depth = 5mm
2 mm 21mm
Distance between slit and 1st groove = 7.9mm
23mm
Distance between Patch and Plasmonic antenna =
3.9 mm
Figure 3.3: Return loss (
) of the proposed plasmonic antenna
The proposed plasmonic antenna resonates at 12GHz with a bandwidth of 243MHz and a gain of
22.42 (13.51Db) with a very low side lobe (-9.6 Db) gain as shown figure 3.4.
Figure 3.4: Farfield Radiation pattern of the proposed plasmonic antenna. (a) 3D Farfield Pattern (b)
Polar coordinate representation
68
Chapter 4
Project Planning and Review of Project Risk
4.1 Project planning and milestone chart
The plan that will be followed to achieve the determined aim and objectives of the project based
on the methodology described in chapter 3 and ends by submitting the dissertation report on the
exact time is shown in the following Gant chart.
69
4.2 Project Risk
One of the main expected risks in this project was to delay the submission of the dissertation due
to taking much time in learning how to use of the simulation software. However, this has been
hardly mitigated during the feasibility study period by learning familiarizing myself with it
through designing and simulating initial Millimetre wave plasmonic antenna. Another expected
risk during the dissertation might come from any delay caused by losing the whole or part of
simulation data because of unexpected machine faults. Thus, backup copies of the simulated data
should be saved regularly. In addition to that, a delay might be caused by the difficulty of
achieving some of the project objectives specially the steerable and direct antenna coupling parts
and this can be mitigated by referring to extra literature, extra investigations and seeking help of
the project‟s supervisor. Nevertheless, to eliminate all expected and unexpected risks, an extra
float week have been included in the project plan so it will compensate any delay.
70
REFERENCES
[1] Ehab A. Omar and Khaled Elsayed. Directional Antenna with Busy Tone for
Capacity Boosting and Energy Savings in Wireless Ad-hoc Networks. In: High-Capacity Optical
Networks and Enabling Technologies (HONET); 2010 Dec 19-21; Cairo, Egypt. P. 91-95.
Available from: IEEE Xplore.
[2] Kasch, Burbank J.L and Andrusenko J. The Effects of Antenna Pointing Error on Bit Error
Rate Performance in Mobile Directional Antenna Applications. In: CCECE „06; 2006 May;
Ontario, Canada. P 1652 – 1657. Available from: IEEE Xplore.
[3] T. D. James, Z. Q. Teo, D. E. Gómez, T. J. Davis and A. Roberts . The plasmonic J-pole
antenna. Applied Physics Letter. 2013; 102:033106.
[4] William L. Barnes, Alain Dereux & Thomas W Ebbesen. Surface plasmon subwavelength
optics. Nature. 2003; 424: 824-830
[5] J.B. Pendry, L Martı´n-Moreno, and F.J. Garcia-Vidal, “Mimicking surface
plasmons with structured surfaces”, Science, August 2005, 305:847.
[6] Firdaus M, Zhirun Hu and Abdalla M A. Ultra high gain of plasmonic inspired antenna and
its beam forming. Antennas and Propagation Conference (LAPC); 2012 Nov 12-13.
Loughborough, UK. Available from: IEEE Xplore.
[7] Guangyuan Li, Feng Xiao, Li Kun, Alameh K and Anshi Xu. Theory, Figures of Merit, and
Design Recipe of the Plasmonic Structure Composed of a Nano-Slit Aperture Surrounded by
Surface Corrugations. IEEE. 2012m, 30 (Issue: 15): 2405 – 2414.
[8] Kyoung Youl Park, Meierbachtol C.S., Wiwatcharagoses N and Chahal P. Surface plasmonassisted terahertz imaging array. In: Electronic Components and Technology Conference (ECTC),
2012 June 1 2012; San Diego, CA. p. 1846 – 1851. Available from: IEEE Xplore.
[9] Akalin T, Beruete M, Navarro-Cia, Ducournau G, Lampin J.F. and Sorolla M. Plasmonic
antenna for beam-shaping of Terahertz Quantum Cascade Lasers. In: Antennas and Propagation
(EUCAP). 2011 April 11-15; Rome, Italy. P.3329 – 3330. Available from: IEEE.Xplore.
[10] Haofei Shi, Xingzhan Wei, Zeyu Zhao, XiaochunDong,Yueguang Lu, and Chunlei Du,
“A new surface wave antenna based spoof surface plasmon mechanism”, Microwave And
Optical Technology Letters, October 2010, 52:10.
[11] Cheng Huang , Zeyu Zhao and Xiangang Luo. A Highly Directive Slot Antenna with
Dielectric Loaded Corrugated Structure. In: International symposium on antenna and propagation
(ISAP); 2011, 25 Oct – 28 Oct. Jeju, South Korea.
[12] Beruete, M Campillo , Dolado J.S, Rodriguez-Seco, Perea E, Falcone F and Sorolla M.
Very low-profile “Bull‟s Eye” feeder antenna. Antennas and Wireless Propagation Letters,
IEEE.2005; 4: 365 – 368.
[13] Balanis C.A, “Antenna theory: analysis and design”, New Jersey: John Wiley & Sons,
2005,
71
APPENDIX A
RISK ASSESMENT
73
74
75
Appendix B
Rectangular Patch Antenna Design
A rectangular patch antenna is designed based on the transmission line model. The patch width
has a minor effect on the resonant frequency and major effect on the antenna‟s bandwidth and
radiation patterns. However, the Patch length controls the resonant frequency. The design
methodology for a patch antenna based on transmission line model is as following [13]:
B. Calculation Of The Width And Length Of The Rectangular Patch.
Step 1: Calculation of the Width (W)
√
Where, c is velocity of light,
is the resonant frequency and
is the dielectric constant.
Step 2: Calculating the Length (L)
To calculate the length of the patch, the effective dielectric constant
) should first be
calculated. As the frequency of operation increases the effective dielectric constant approaches
the value of the dielectric constant of the substrate is given by:
(
=
)
(
=
for
(1)
)
[
√
] for
(2)
Then , the actual length is given by the following equation :
√
√
–2
√
(3)
Where
L is given by :
(
)
(
)
The final dimension of the optimized antenna are illustrated in table 1.
76
(4)
Figure 1: Model of Rectangular patch antenna
Table 1: description of rectangular patch antenna parameters
Patch Length L = 4.77mm
Patch width W= 5mm
Inset depth
Inset width = 1.5 mm
=1.5mm
Substrate thickness = 1.6 mm
Feed Line Width
Substrate dielectric constant = 5.2
Antenna Geometry = 10mm
= 0.80 mm
8.5mm
The designed patch antenna has a bandwidth of 430MHz and has a gain of 3.88 (5.89 dB) at
12GHz .
parameter of the proposed antenna is shown in figure 2 and the farefield radiation
patterns are shown in figure 3 and for simultaneously .
Figure 2 : simulated
parameter of the proposed patch antenna
77
Figure 3: Simulated farfield of the proposed patch antenna. (a) polar coordinate representation (b)
3D representation.
78