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June 22,1943.
>
H. GRANGER
'
2,322,233
COAXIAL TRANSMISSION LINE TERMINAL
Filed May 2, 1941
V “ax/mater”
INVENTOR.
Ha ro/d Granger
yg'romvsv
0 Ora-1403591)
2,322,233
Patented June 22.‘ 196
UNITED STATES PATENTT OFFICE
‘
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coaxial. rasssmssrosnmnnaumsr.
mm Granger, United States Marine Corps
Application May '2, 1941, Serial No. 391,4"
scams. (Cl. ‘174-19)
(Grantednnder the act oi’ March 8, 1888, as
}
amended April 30, 1928;.3'" 0. G. 78'!)
.
tion
of
a
glass-io-metal
seal;
to
provide
a ter
My invention relates to a coaxial transmission
minal ot the stated character through which gas
line terminal and, more particularly, to a ter
may be conveniently introduced into or with
minal of the stated character that maintains
drawn from the transmission line; and to pro
its ?uid-tight integrity unimpaired in use and
vide a terminal or the character noted above
provides a convenient means for connecting
which incorporates a novel arrangement 01'
electrical conductors thereto. '
parts (or protecting the glass-to-metal seal and
As is well known, coaxial transmission lines
for facilitating the connection of conductors to
are employed for the transmission or reception
of radio frequency energy because of the many '
the transmission line.
-
Other objects and many oi the attendant ad
structural and electrical advantages inherent 10
therein. Among the advantages possessed by ‘ vantages of this invention will be readily ap
coaxial transmission lines are the maintenance _
by the same 01 substantially uniform electrical
characteristics under all service conditions and
the ability to increase the power transmission
thereof either by the partial evacuation of or by
the introduction of gas under pressure into the
preciated as the same becomes better under
‘ stood by reference to the following detailed de
' scription whenconsidered in connection with‘
the accompanying sheet. of drawing, wherein:
Fig. 1 is a view in partial sectional elevation
of one embodiment oi the terminal oi’ the pres- v
ent invention shown connected to the transmis
sion line and as incorporating an inner gas con
space between the outer and inner concentric
conductors,
g
i
a
-
-
In order to insure the retention of the above 20 veying conductor;
Fig. 2 is a view in partial sectional elevation
enumerated advantages, it is essential that the
oi another embodiment of the terminal of the
coaxial transmission line be provided with a ter
- minal that maintains its ?uid-tight integrity
present invention shown connected to the trans
unimpaired in use. This is achieved in accord
mission line and as incorporating a solid inner
ance with the present invention by the provision 25
Fig." 3 is a view in partial sectional elevation
oi’ a terminal comprised of a pair of insulatingly
of the novel arrangement of parts that may be I
spaced concentric metallic conductors and a lay:
employed in conjunction with either of the em
er of glass for sealing one conductor-f-yto-"the other.
bodiments depicted in Figs. 1 and 2 for protect
' The ‘glass has .a low dielectric loss at radio ire
quenciesand- a temperature coeiiicient of ex‘ 30 ing the glass-to-metal seal and' for facilitating
the connection of conductors to the transmission
pansion‘substantially equal to that of the me
conductor;
tallic conductors to thus insure a vacuum-tight
seal.
"
~
line;
‘ vide a ready means for partially evacuatingthe
under pressure into the space therebetween. A“
40
the inner conductor of the concentric terminal
pair may be supported in an insulating manner
from a metallic sleeve secured to the outer con
iductoroi the concentric terminal pair‘ and ex
' tending beyond the seal therebetween. This is 45
chanical stresses that would otherwise be im
posed upon the seal through the securement or
conductors to‘ the connector or otherwise.
In the light of the foregoing, it is among the
several;
of my invention to provide a co
axial
‘
on line terminal in which ?uid
tight integrity‘ is achieved through the utilisa
t
_
i
-
Turning now to Fig. l or the drawing, there
is shown depicted therein a coaxial transmission
line vterminal identi?ed in general‘by the refer
ence character i and comprised of the pair ‘of
space between the outer and inner conductors
v of the transmission line or for introducing gas
tive covering for the seal but also takes the me
o
'
- ture delineated in Fig. 3.
The inner conductor oi'the concentric termi- .
rial pair may be tubular, if desired, to thus pro ‘35
_a feature of importance in the present inven
tion since the sleeve not only provides 'a' protec:
I
_
Fig. 4 is a view in end elevation of the struc
'
suitable connector electrically continuous with
and
‘
insulatingly spaced concentric metallic conduc
tors 2 and l sealed together by the layer 0! glass
4. The glass I has a low dielectric low at radio
frequencies and a temperature coe?lcient of en
pansion substantially equal to that or the metal
liczconductors I and 3,_ as willbe pointed‘ out '
more in detail hereinafter.
2’ Thecoaxial transmission line 5 is shown with.
its inner conductor I in telescoping and ,electri
cally continuous engagement with the inner tilbular gas conveying conductor 2 o! the conceni
~tric terminal pair. electrical continuity being
achieved by soldering or otherwise securingthe
telescoping conductors I and t at their iunction
point; A metallic sleeve ‘In is secured in ?uid
tight relation to‘the open end of the outer con
ductor'l o! the tr
line and to the Outer
2
asaasss
concentric conductor I of the terminal pair in
stand sudden changes of temperature without
any suitable manner, as by sweating or welding
fracture.
the sleeve ‘I and the outer concentric conductors
3 and l at their Junction points. [A pressure
gauge I of any conventional prior art construc
tion may be optionally employed to indicate the
pressure of the gas between. the inner and outer
concentric conductors l and I of the t
By way of illustration there are tabulated be
low a number of hero-silicate glasses that may
be advantageously used in the iabrication of the
seal:
-
-
>
Tut: I
Compositions and properties of me hard classes
line I.
The inner gas conveying conductor 2 of the 10.
A
concentric terminal pair is suitably apertured
at I. by providing a number 01' diametrical per
forations through the conductor so that gas may
No'
be easily introduced within or withdrawn from‘
the transmission line. By virtue of this con 15
struction it is possible to provide the transmis
.
n.
neal
n pansivit ,
26! to 325's.
ing
Par- Per- Per- Per- Per
point1 cent cent cent cent cent
BiOs NIAO Bros A110! PhD
'
'0.
1
Compositions
s.1x1o-'/o.° ______ .-
see
.
724
as
10.2
5.1
1.8
2
4.sx10-'/o.' ______ ._
m
01.0
as
no
2.0 ____ _.
sion line with dry air or a dry inert gas at or
a
3.2Xl0"/C.° ______ ._
sso
80.0
to
13.0‘10 .... ..
above atmospheric pressure or to evacuate the
transmission line to. any desired degree of pres
I Lowest temperature at which strains will deny to an inapprcci
sure. After the desired gas pressure is atab 20 able value after exposure for ?fteen hours.
lished within the transmission line, the inner
tubular conductor 2 of the terminal pair is her,
While tungsten and molybdenum have coeiil~
cients of expansion of the right order of magni
metically sealed in any suitable manner as by
tude for sealing to the boro-silicate glasses and
' crimping the same and soldering the conductor
hence may be employed in the fabrication of the
at the crimped portion.
25 concentric terminal conductors 2 and I to form
The embodiment depicted in Fig.2 of the draw
- an emcient vacuum-tight seal, they possess the
ing is in all respects identical with that of Fig.
disadvantage of being rather expensive and dii~
1 except that the inner concentric conductor 2
ilcult to ‘machine. In the fabrication of the con
of the terminal I is solid instead of tubular and
ductors I and l, I prefer, therefore, to use in
that the sleeve ‘I is provided with a connection 30 stead an nickel-cobalt-iron alloy that forms an
H for introducing or withdrawing gas from the
emcient vacuum-tight seal with the bore-silicate
transmission line B. I After the desired pressure
glasses. In general, the ranges of the principal
is established within the transmission line, the
ingredients of the alloy are from 15% to 32%
terminal portion ll integral with the 'sleeve 1
nickel, 12% to 45% cobalt, less than 1% manga
may be sealed in any suitable manner.‘ As shown 35 nese, and the remainder iron.
in Fig. 2 of the drawing, the. inner conductor 2
By way of example, there are tabulated below
or the terminal and the inner conductor 0 of the
a number 01 nickel-cobalt-iron alloys that may
be employed in making a vacuum-tight seal with
transmission line are butt welded at l2 or other
the boro-silicate glasses: ;
wise suitably secured at this point to establish
electrical continuity therebetween. with the ex
ceptions noted above the construction in Fig. 2
is identical with that of Fig. 1. Hence, similar
Timi-L II
~
Compositions and properties voi some alloys
reference characters have been employed in both 4
figures to designate corresponding parts“
Compositions
It is known that the electrical losses in solid 46
dielectrics increase with frequency and that
Expansivit
No‘
Y
~ these losses are principally due to dielectric hys
teresis. The electrical energy lost as a result
of dielectric hysteresis appears in the form of
heat generated within the dielectric, the heat so
generated being cumulative in part and result
ing in 'higher temperatures within the dielectric
with increase in the electrical losses.
_.
In order, therefore, to insure‘ a vacuum-tight
seal in the terminal or the present invention. it
is essential that the dielectric material I have a
low loss at radio frequencies, a high melting
point, high resistance to thermal shock and a
coeiiicient of expansion substantially equal to
-
25 to 326° 5.’
l
0.2)(10'4'C.°_-._-
2
0004/6.-_____ _.
3 ‘3.0XIO"/O.’._...
Per
Per
Per
Per
Per
cent
cent
cent
cent
cent
vNi
00
Fe
Mn
C
32
16
51.1.
0.80
0. l0
2s
17
53. a
o. 20
0. 2o
29.8
15.5
54.18
0. 22
0. 30
In order to make a successful seal, the mem
clents of expansion of the metal and the glass
must be substantially the same over the temper
ature ranges within which the metal and glass
areboth elastic. A large difference in the coefii
cients of expansion produces stresses which may
cause the glass to crack when cooled to room tem
perature and thus destroy the vacuum-tight seal.
that of the metallic conductors 2 and I sealed
Some degree of diiierential expansion, however.
thereto. In accordance with the Present inven
between the metal and glass may be tolerated
tion I employ as the dielectric sealing. material
and is even desirable. Thus,'it has been found
4 glasses having the above cited characteristics
that the alloys designated by the numbers 1, 2
and in particular the hard glasses because of 66 and 3 in Table II above may be sealed respec
their lower dielectric loss at- radio frequencies.
tively to the glasses designated by the numbers
Among the hard glasses I have found it ad
1, 2 and 3 in Table I- to ‘form therewith a vacu
vantageous to use the bore-silicate glasses which
um-tight joint under the conditions encountered
have an expansivity or coefficient of expansion
in use.
a
varying in general between 3.0 and [0x104 cm. 70
For protecting the glass-to-metal seal and for
per cm. per degree C. The dielectric losses of
facilitating the connection of conductors to the
these glasses at radio frequencies is not only ex
transmission line, the construction depicted in
ceedingly low but these glasses by virtue of their
Figs. 3 and 4 may be employed with either of the
low coei’iicient of expansion exhibit a high re
embodiments heretofore described. As shown
sistance to thermal shock. Thus, they will with— 75 more particularly in Fig. 3, a metallic sleeve II
3
2,832,233
operation of my invention and have illustrated
and described what I now consider to represent
its best embodiments. However, I desire to have
it understood that within the scope of the ap
pended claims the invention may be practiced
otherwise than as‘ speci?cally illustrated and de
is ?rmly secured in any suitable manner as by
welding or sweating to the outer conductor 3
of the terminal pair and extends well beyond
the’ seal 4 therebetween to thus form a protec
tive housing for the same.
An electrical insu
lator ll of any suitable material, such as a ce
ramic. material, is longitudinally apertured and
terminally recessed to receive respectively the
scribed.
conductor 2 and the connector l5 electric-ally con
. tinuous therewith.
-
The invention herein described and claimed ~
vmay be used and manufactured by or for the
Government of the United States of America for .
The insulator H as shown
is securely a?ixed to the sleeve It in any conven
governmental purposes without the-payment of
lent manner as by crimping the sleeve firmly at '
any royalties thereon or therefor.
l6 into an ‘annular groove of the insulator ll.
While any convenient type. of connector may
be employed I have shown the connector l5 sup
ported from the ceramic insulator H as including
a metallic sleeve I6 threaded at both ends and
terminating centrally in a metallic disc l‘l in
tegral with or otherwise secured to the threaded
sleeve. The sleeve I6 is sweated or soldered to
the inner conductor 2 of the concentric termié
nal pair to establish electrical continuity there
between. One-or more nuts it are in threaded
engagement with the sleeve |6~ so that a good
electrical connection may be made to a conductor
by interposing and clamping the same between
I claim: '
1. A coaxial transmission line terminal com
prising in combination a pair 01' insulatingly
spaced concentric metallic conductors and a layer
oi! glass for sealing one conductor to the other,
the said glass having a low high frequency di
electric loss and a temperature coe?icient oi.’ ex
pansion substantially equal to that oi the metal
lic conductors, a tubular metallic conductor se
cured to the outer conductor of-the concentric
conductor pair and extending beyond the seal
therebetween, an insulator a?lxed to the tubular
metallic conductor and a connectorpsupported
from said insulator, the said connector being
electrically continuous with the inner conductor
the disc I1 and the nut i'l next adjacent there
of the concentric conductor pair.
to. Since the connector I! is soldered or sweated
' to the conductor 2 and has a portion thereof em
bedded in the terminal recess 01 the insulator
veying metallic conductor ‘concentric with and
H, a rigid and secure mounting is provided for,
insulatingly spaced from an outer tubular metal
lic conductor and a layer of glass (or sealing one
conductor to the other, the said glass having a
low high frequency dielectric loss and a tempera
the same.
By virtue of the foregoing construction, the
glass-to-metal seal is protected against mechani
cal shocks and hazards. For not only does the
sleeve I! provide a protective covering for the
seal I but it also takes the mechanical stresses.
that would otherwise be imposed upon the seal
through the securement of the conductors to
the connector I! or otherwise. 'Finally, the con
ture coe?lcientot ‘expansion substantially equal
to that of the metallic conductors, a metallic
sleeve secured to the 'outer tubular conductor of
‘the concentric conductor pair and extending be
40 yond the seal therebetween, an insulator a?ixed,
. struction delineated in Fig. 3 provides a very
convenient means for connecting a conductor to
, _the transmission line.
According to the provisions of the patent stat- ..
utes, I have set forth the principle and modeof
.
2. A coaxial transmission lineterminal com
prising in combination an inner tubular gas con
to the sleeve and a connector supported. from
' said insulator, the said connector being electri-'_ .
cally continuous with the inner tubular conduc
tor oi’ the concentric conductor pair.
’
~ HAROLDGRANGER.