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Nov. 6, 1962
3,062,983
G. c. VAN HOVEN
HIGH FREQUENCY ENERGY INTERCHANGE DEVICE
Filed April 28, 1959
INVENTOR.
BY M»
United States Patent @?tice
it
3,052,983
Patented Nov. 6, ‘1 962
2
line which is extremely rugged and acts as a support
3,062,983
for the transmission line.
In carrying out the present invention, a high frequency
energy interchange device of the traveling-wave type is
provided and support for the slow-wave transmission line
HIGH FREQUENCY ENERGY INTERCHANGE
DEVICE
Gerard C. Van Hoven, Palo Alto, Calif., assignor to Gen
eral Electric Company, a corporation of New York
as well as coupling of electromagnetic waves between the
Filed Apr. 28, 1959, Ser. No. 809,444
3 Claims. (Cl. 3l5--3.6)
helical slow~wave transmission line and input and output
waveguides is provided by extending a conductive trans
This invention relates to high frequency energy inter—
ducer element (antenna) across the waveguide in ques~
change devices of the type which rely upon an interchange 10 tion and securing it to more than one of the end turns of
of energy between a stream of electrons and electromag
the slow-Wave transmission line.
netic waves produced ‘by radio frequency ?elds in the
The novel features which are believed to be character
region of the electron stream. More particularly, the
istic of the invention are speci?cally set forth in the ap
invention relates to such a device wherein the electro
pended claims. The invention itself, however, both as
magnetic waves are propagated along a slow-wave trans
to its organization and method of operation together
mission line of the helix or helix-derived type and has
with further objects and advantages thereof, may best be
as an important feature the provision of an improved
understood by reference to the following description taken
in connection with the accompanying drawing in which:
arrangement for coupling the circuit helix or helices of
the device to input and output transmission lines of the
FIGURE 1 is a partially broken away side elevation of
standard rectangular waveguide type.
a traveling-wave ampli?er which incorporates the present
In a conventional traveling-wave ampli?er tube of the
helix type, an electron stream is projected along an elon
gated helix at a velocity approximately equal to the axial
invention;
FIGURE 2 is a transverse section through the input
‘ waveguide taken on line 2—2 of FIGURE 1 and looking
phase velocity of electromagnetic waves traveling along
into the end of the slow-wave circuit;
the helix. By successive processes of electron velocity 25
FIGURE 3 is an enlarged‘ and partial, central, vertical,
modulation and inductive output (magnetic induction),
longitudinal section through the input end of the travel
the stream is modulated by the electric ?eld set up along
ing-Wave tube of FIGURE 1 as projected from line 3—3
the helix by the ‘electromagnetic wave, and the modulated
of the transverse section of FIGURE 2 and omitting part
stream gives up energy to the wave to increase its ampli
of the slow-wave transmission line to illustrate in detail
tude.
30 the input coupling of the present invention;
One of the important problems in the design of travel
FIGURE 4 is a perspective view of the coupling pin
ing-wave ampli?ers is the problem of introducing electro
utilized at the input and output of the traveling-wave
magnetic waves onto the slow-wave transmission line from
an input line such as a common waveguide of rectangular
ampli?er; and
cross section and extracting the ampli?ed electromagnetic
an end view of the helical slow-wave transmission line
waves from the transmission line.
FIGURE 5 is an enlarged and detailed view showing
It is characteristic
with a coupling pin in place to illustrate the coupling
of traveling-wave ampli?ers that interaction between the
con?guration.
electron stream and the circuit takes place over an ex
tremely wide band of frequencies and it is frequently
found that the useful range of frequencies of the ampli?er
is limited by the transducers or coupling between a wave
guide and the slow-wave circuit. As a consequence, it
is extremely desirable to have a coupling means or trans
ducer which is at least as broad band as the traveling-wave
ampli?er itself. Another desirable characteristic of the
transducer is that it have high power handling capabilities,
particularly since the output transducer is the only place
Where the full radio frequency power developed by the
ampli?er actually occurs.
In FIGURE 1 of the drawing, a traveling-wave tube
is illustrated. The traveling-wave tube includes an enve
40 lope 10 which serves as a vacuum enclosure. As illus~
45
trated, the envelope 10 has an enlarged cylindrical ceramic
gun enclosing portion 11 at one end, a long metallic cylin
drical portion 12 forming the central part, and enlarged
cylindrical metal and ceramic collector portion 13 form
ing the opposite end. The central elongated cylindrical
metallic portion is connected to the enlarged ceramic por
tions 11 and 13 at its opposite ends by input and out
.put metallic waveguides 14 and 15, respectively. The
input and output waveguides 14 and 15 are of rectangular
' Accordingly, it is an object of the present invention to 50 cross section and extend across the cylindrical structure
provide a high frequency energy interchange device of the
traveling-wave type with a transducer to provide coupling
between one or more helical transmission lines and a
with their longitudinal axes perpendicular to the longi
tudinal axis of the cylindrical envelope 10.
The small cylindrical central portion of the envelope
rectangular waveguide which transducer will couple a
it; houses the interaction transmission line 16, the en
wide band of frequencies and be capable of handling
larged cylindrical ceramicportion 11 at the input end of
high powers.
the device, i.e., adjacent the input waveguide 14, houses
Another difficult problem encountered in constructing
an electron gun (not shown) which is designed to pro
such devices is that of making the structure sui?ciently
duce the desired electron streams, and the enlarged metal
rugged to withstand the rigors of assembly and the
ceramic portion 13 at the output end of the device serves
shocks and vibrations which the tube may be subject to in 60 to collect electrons from the electron streams projected
use. Since the slow-Wave transmission lines in such de
down the length of the device, thereby to dissipate residual
vices and the transitions between the slow-wave trans
mission line and input and output waveguides are gen
erally at least as delicate as any other part of the struc
energy in the streams. Thus, the electron gun projects
electron streams down the length of the slow-wave trans,
mission line 16 in such a manner that they interact with
ture, they are most in need of ruggedization. Moreover, 65 the electromagnetic waves propagated down the slow-wave
the coupling e?iciency is often critically dependent upon
transmission line 16 to produce ampli?cation. Electrons,
from the stream which pass through the helical trans
dimension is quite important.
mission line 1d are collected inside the enlarged metal
Accordingly, it is another object of the present inven
ceramic collector portion 13.
tion to provide, in a high frequency energy interchange 70 The electron gun structure enclosed by the enlarged
device of the travelingwave type, a transition between
ceramic portion 11 is not illustrated and described in
conventional Waveguide and a slow-wave transmission
detail since the speci?c structure does‘not constitute a:
the exact transducer con?guration so that rigidity of
3,062,983
d,‘
part of the present invention. One particular structure
for producing four parallel electron streams may be com
prised of four side-by-side and independent electron guns
of conventional design and the streams from these guns
may be focused over their entire length by producing a
magnetic ?eld axially along the structure. That is, the
space charge of the electrons in the streams may be pre
vented from spreading the electrons to such an extent that
In order to provide a path for each of the electron
streams to pass down the full length of the envelope 10,
the supporting plugs 23 are provided with four beam
passing apertures 24 spaced equidistant around the center
of the cylindrical plug 23. The plug 23 at the input end
of the envelope 10 is positioned in a cylindrical aperture
25 provided in the wall of the input waveguide 14 which
is opposite the metallic central portion 12 of the envelope
with its four beam passing apertures in register with the
they pass out of the interaction region and intercept the
electron streams from the four electron guns and the
10
slow-wave transmission line by producing such a magnetic
central axes of the four helical conductors 17, 18, 20
?eld axially along the structure. This is typically done by
and 21 of the slow-wave transmission line 16. The sup
providing a long annular solenoid (also not shown) which
port plug 23 is ?xed in position in the input waveguide 14
surrounds the transmission line enclosing portion 12 of
the tube and is concentric therewith.
To simplify the
present drawing and description, a magnetic ?eld produc
ing solenoid is not illustrated.
For an understanding of the exact con?guration of the
slow-wave transmission line 16 illustrated, reference may
be had to FIGURES 2 and 5. From these ?gures, it is
seen that the slow-wave transmission line 16 is a com
posite slow-wave structure consisting of four helical con
ductors 17, 18, 2G and 21, each having the same diam
eter, pitch and axial length. The helical conductors 17,
18, Ztl and 21 are arranged so that their axes form the
long parallel sides of an elongated rectangular parallelepi
ped, the other sides of which are equal to the diameter
of the individual helices. Each of the helical conductors
is illustrated as being wound in the opposite sense to the
immediately adjacent conductors. That is, the diametri
cally opposed helical conductors (2t) and 17) in the par
allelepiped on the upper and lower corners thereof are
wound right-handed as indicated by arrows adjacent each
of the conductors and the two conductors 18 and 21 on
the remaining two corners are wound left-handed, also
as indicated by the arrows adjacent the conductors. But
of course, they all may be wound in the same sense if
desired. With the arrangement illustrated, each helical
conductor contacts two adjacent helical conductors at
points (on turns) along their length that are spaced a
turn apart and are preferably brazed together at each
point of contact. The reason for utilizing such parallel
helical conductors is set forth in detail in the John L. Putz
application, Serial Number 657,367, ?led May 6, 1957,
entitled “Electron Discharge Devices,” and assigned to
the assignee of the present invention. Consequently, the
characteristics of the circuit 16 are not discussed in detail.
However, it is well to note that the invention is not limited
to the speci?c circuit 16 illustrated but is shown in con
nection with this circuit since it is utilized to such ad
vantage with this particular arrangement.
Since the four helical conductors 17, 18, 20 and 21 are
brazed together turn to turn down their length, it is con
venient to support them in the cylindrical barrel or trans
by brazing.
The support plug 23 at the output or collector end of
the envelope 10 is ?xed in position in the same manner
with its beam passing apertures 24 also in register with
the axes of the helical conductors 17, 18, 20 and 21.
Thus, electron streams may be directed down the length
of each of the helical conductors 17, 18, 20 and 21 of
the transmission line 16 and out through the output sup
porting plug 23 into the collector section 13.
In addition to the four electron stream apertures in the
input and output plugs 23, there is provided a centrally
located aperture 26 which is provided for the purpose of
receiving and holding a wave coupling and transmission
line supporting pin 27. The speci?c con?guration of the
coupling pin 27 is not too critical. However, as may
best be seen in FIGURE 4, the pin 27 has one cylindrical
30 end 28, an intermediate shoulder 30, which is slightly
larger than the cylindrical portion 28 of the pin, and a
substantially square end 31. As illustrated, the substan
tially square end 31 is formed by chamfering four ?at
sides on cylindrical stock of the same diameter as the op
posite end portion 28. The round end 28 of the pin 27
is positioned within the centrally located aperture 26 in
the beam passing and transmission line supporting plug
23 and extends across the input or output waveguide. The
four sided end 31 of the pin 27 projects in between the
individual helices of the main transmission line 16 so that
the intermediate shoulder 30 abuts the end turns of the
helices. At least the ?rst two turns of each of the helices
17, 18, 20 and 21, that is, the two end turns of the helices
at both of their opposite ends are brazed to the pin 27
which projects between the turns. In this manner, elec
tromagnetic energy introduced into the input waveguide
‘14 is impinged upon the coupling pin 27 at the input end
of the device which is brazed to the ?rst two turns of
each of the individual helices and coupled or transferred
onto the slow-wave transmission line 16.
The wave 18
propagated from the gun end of the tube toward the out
put or collector end and interaction takes place between
the wave and the electron streams in the conventional
manner. The ampli?ed radio frequency energy impinges
on the coupling pin 27 at the output end of the envelope
four rods 22 of dielectric .material, such as sapphire or 55 10 and is thereby coupled to the output waveguide 15.
quartz, which are of substantially circular cross section.
The coupling thus provided has proved to be capable
Each of the rods 22 extends down the length of the slow
of a ?fty percent band width with excellent mechanical
mission line enclosing portion 12 of the envelope 10 by
wave transmission line 16 in contact with two adjacent
helical conductors so that the center lines of the rods 22
and thermal qualities. This particular coupling arrange
form the parallel sides of an elongated rectangular par 60 ment effectively lengthens the helical transmission line
16 as far as its heat conduction properties are concerned
allelepiped which sides are displaced 45 degrees with re
and increases its mass in the region of the transition.
spect to the elongated sides of the parallelepiped de?ned
Further, the arrangement greatly increases the rigidity
by the longitudinal axes of the conductors 17, 18, 20
of the con?guration in the regions in which its shape is
and 21.
It is noted that the opposite ends of the slow-wave 65 most important.
The cylindrical gun enclosing ceramic portion 11 is
transmission line 16 and the supporting dielectric rods
provided at its outer end with a metallic ?ange 32 brazed
22 extend into the input and output waveguides 14 and
thereto and a disc-shaped metallic end cap 33 heliarced
15. In the wall of the input and output waveguides 14
to the ?ange 32 to provide a vacuum tight seal for the
and 15, directly opposite the ends of the transmission line
16, input and output transmission line supporting and 70 outer end of the ceramic gun enclosing portion. At its
opposite end, the gun enclosing ceramic portion 11 is
beam passing cylindrical conductive plugs 23 are pro
provided
with a cup-shaped ?ange 34 which extends out
vided. Since both of these plugs 23 are identical and
wardly from the outer periphery of the cylindrical ce
serve the same general purpose, only the plug 23 at the
ramic and back towards the outer end of the ceramic
input end of the envelope It} and its associated structure
75 cylinder 11. This cup-shaped ?ange 34 is concentric
are illustrated in detail (see FIGURES l and 3).
5
3,082,983
6
with the ceramic cylinder. 11.-and-is provided for pur
between and electricallyand mechanically connected to
poses of alignment. __A (matching cup-shaped metallic
at'le’ast two end turns on each of said transmission lines
?ange 35 is brazed to the outer end or outer wall of
the input__waveguide_14 in such a manner that it is con
and extending across the waveguide with its, opposite end
?xed to the opposite broad wall of said waveguide.
centric with the aperture 25 therethrough provided for
the transmission line supporting and beam passing end
plug 23. Thus, the cup-shaped ?ange 34 around the
outer periphery of the ceramic gun enclosing portion 11
may be ?tted snugly within the cup-shaped ?ange 35
on the input waveguide and heliarced thereto in a man
her to form. a vacuum tight seal.
'
__
cluding four helical conductors arranged side by side
10 with parallel longitudinal axes and turns along the length
of each helical conductor connected to corresponding
The central cylindrical transmission line enclosing por
tion 12 of the envelope It) is sealed at its opposite ends
turns on the two adjacent helical conductors to form
an array with a space therebetween; electron gun means
in a vacuum tight manner to both the input and output
close to one end of said transmission line for project
waveguides. The opposite wall of the output waveguide 15 ing a stream of electrons down the axis of each helical
15 is, as previously described, provided with an aper
conductor for interaction with electromagnetic waves
ture 25 of the proper size to receive a transmission
propagated therealong; ‘a collector at the opposite end
line supporting and beam passing plug 23. A concen
tric metal cup-shaped ?ange 36 is provided around this
aperture 25 for the purpose of receiving and aligning 20
the collector section 13 of the envelope 10 on the outer
Wall of the output waveguide 15.
The collector section 13 of the traveling-wave tube is
not illustrated in great detail since its speci?c con?gura
of said transmission line for collection of electrons; indi
vidual input and output waveguides of rectangular cross
section extending transverse to said traveling-wave tube
between said transmission line and said gun and said
transmission line and said collector, respectively, for
the purpose of introducing and extracting electromag-v
netic waves, said input and output waveguides being pro
tion does not constitute a part of the present invention. 25 vided with an aperture through the broad walls in align
However, as illustrated in FIGURE 1, the collector in
ment with said transmission line and electron gun means,
cludes a hollow cylindrical conductor member 37 which
said transmission line positioned with its longitudinal
is provided for the purpose of collecting the electrons
axis perpendicular to the plane of the broad walls of
from the electron streams. The collector member 37
of said input and output waveguides with one end
is provided with a cup-shaped ?ange portion 38 whfch 30 each
protruding
through the aperture in the adjacent broad
extends outwardly from one end of the main body por
wall;
input
and output coupling means positioned at
tion forward toward the tube envelope 10. A hollow
opposite ends of said slow-wave transmission line, each
tubular ceramic member 40‘ is brazed inside the ?ange
coupling means including a coupling pin positioned with
36 on the outer Wall of output waveguide 15 at one end
its longitudinal axis parallel to the longitudinal axis of
and inside the cup-shaped flange 38 on the collector mem 35
said slow-wave transmission line and one end in the
ber 37 to provide a vacuum tight seal and also to insulate
space provided therebetween and electrically and me
the collector 37 from the conductive output waveguide 15.
chanically connected to at two end turns on at least one
The enclosure is made vacuum tight by providing
of said helical conductors and extending across the ad
vacuum tight ceramic windows (not shown) at the outer
jacent rectangular waveguide with its opposite end ?xed
ends of the input and output waveguides 14 and 15.
to the opposite broad wall of the respective waveguide.
Thus, in accordance with the principles of the inven
3. A high frequency energy interchange device of the
tion, a traveling-wave tube is provided with an extremely
traveling-Wave type including in combination an elon
broad band coupling between the transmission line and
gated evacuated envelope containing an elongated slow
input and output waveguides which coupling has the
advantages of being extremely rugged, rigidly support 45 wave transmission line, said slow-wave transmission line
including four helical conductors arranged side by side
ing the ends of the tube transmission line and providing
excellent heat dissipating properties.
with parallel longitudinal axes and turns along the length
While a particular embodiment of the invention has
of each helical conductor connected to corresponding
been described and illustrated, it will, of course, be under
turns on the two adjacent helical conductors to form a
stood that the invention is not limited thereto, since many 50 cluster with a space therebetween; electron gun means
modi?cations, both in the circuit arrangement and in
close to one end of said transmission line for projecting
the instrumentalities employed, may be made. It is con
a stream of electrons down the longitudinal axis of each
templated that the appended claims will cover any such
helical conductor for interaction with electromagnetic
modi?cations as fall within the true spirit and scope of
waves thereon; a collector at the opposite end of said
the invention.
55 transmission line for collection of electrons; input and
What I claim is new and desire to secure by Letters
Patent of the United States is:
l. A transducer for coupling electromagnetic waves
between a rectangular waveguide having two broad walls
output waveguides of rectangular cross section extending '
transverse to said traveling-wave tube between said trans
mission line and said gun and said transmission line and
‘said collector, respectively, for the purpose of introduc
and two narrow walls and a slow-wave transmission line 60 ing and extracting electromagnetic waves, said input and
which includes four helical conductors arranged side by
side with parallel longitudinal axes and turns along the
output waveguides being provided with an aperture
throughbroad walls in alignment with said transmission
length of each helical conductor connected to corre
line and electron gun means; individual coupling and
sponding turns on the two adjacent helical conductors to
supporting plugs having a centrally located aperture and
form an array de?ning a space therebetween, the rec 65 four electron stream passing apertures spaced equidis
tangular waveguide being provided with an aperture
tant therearound, said individual plugs positioned in the
through at least one broad wall, said slow wave trans
apertures provided in the broad wall of said input and
mission line being positioned with its longitudinal axis
output waveguides which are adjacent said electron gun
perpendicular to the plane of the said one broad wall
means and said collector, respectively, with each of said
of said rectangular waveguide and one end protruding 70 stream passing apertures disposed to pass an electron
through the aperture therein, said transducer including
stream, said transmission line positioned with opposite
ends protruding through an aperture in the adjacent
allel to the longitudinal axis of said slow wave trans
broad wall of said input and output waveguides with
mission line and one end in the space provided there 75 individual helical conductors coaxially disposed relative
a coupling pin positioned with its longitudinal axis par~
g
2. In combination in a high frequency energy inter
change device of the traveling-wave type, an elongated
evacuated envelope containing an elongated slow-wave
transmission line, said slow-wave transmission line in
8,062,988
7
References Cited in the ?le of this patent
UNITED STATES PATENTS
to said stream passing apertures in said plugs; input and
output coupling means positioned at opposite ends of
said slow-wave transmission line, each including a cou
pling pin positioned with one end in the space provided
between helical conductors and electrically and mechan- 5
ically connected to at least two end turns in each of
said conductors and extending across the adjacent input
and output waveguides, respectively, with its opposite
end positioned in the centrally located aperture of its
respective coupling plug.
2,602,143
2,611,102
2,789,247
2,821,652
2,890,370
Pierce ______ __ ________ __ July 1,
Bohlke ______________ __ Sept. 16,
Jonker ______________ __ Apr. 16,
Robertson et a1. ______ __ Jan. 28,
Rogers ______________ __ June 9,
1952
1952
1957
1958
1959
FOREIGN PATENTS
m 1,184,604
France _______________ _- Feb. 9,
1959
UNITED STATES PATENT OFFICE
CERTIFICATE OF CORRECTION
Patent No‘, 3,062,983
November 6, 1962
Gerard C. Van Hoven
It is hereby certified that err
ent requiring correction and that th or appears in the above numbered pat
e said Letters Patent should‘ read as
corrected below.
Column 6, line 37, after "at"
—-
least
——°
, first occurrence,‘ insert
Signed and sealed this 9th day of April 1963.,
(SEAL)
Attest:
ESTON G. JOHNSON
Attesting Officer
DAVID L. LADD
Commissioner of Patents
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