US2520220A - Electron discharge device and associated cavity resonator - Google Patents

Description

Aug. 29, 1950 s. NERGAARD ELECTRON DISCHARGE DEVICE AND ASSOCIATED CAVITY RESONATOR Filed Jan. 24, 1945 km mm mf j m. L

Patented Aug. 29, 1950 ELECTRON DISCHARGE DEVICE AND ASSO- CIATED CAVITY RESONATQR Leon S. Nergaard, Princeton, N. 5., assignor to Radio Corporation of America, a corporation of Delaware Application January 24, 1945, Serial No. 574,283

18 Claims.

My invention relates to electron discharge devices and associated circuits and more particularly to cavity resonator circuits suitable for use with such electron discharge devices.

It is frequently necessary to use cylindrical cavities which can be tuned over a small range. The tuning is usually accomplished by collapsing the cavity axially to vary its volume. This entails a change in spacing between the end plates of the cavity. If the circuit is internal to an electron discharge device associated with a resonator or forms part of the envelope of the device, this change in spacing also changes the interelectrode spacings. If the cavity is exterior to the tube, the change in spacing necessitates moving connections to the tube, which is undesirable if, as is frequently the case, these connections also serve as sup-ports for the electron discharge device.

It is an object of my invention to provide a cavity resonator particularly suitable for use with an electron discharge device and which may be conveniently tuned.

Another object of my invention is to provide a cavity resonator which does not require changing electrode spacings of the electron discharge device in tuning the resonator.

A still further object of my invention is to provide such a resonator which eliminates the need for moving connections, particularly where these connections serve as supports for the electron :1

discharge devices.

The novel features which I believe to be characteristic of invention are set forth with particularly in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a longitudinal section of a cavity resonator illustrating the principles of my invention, Figure 2 is a transverse section taken along the line 22 of Figure 1, Figure 3 shows an electron discharge device of the triode type utilizing input and output cavity resonators and utilizing my invention, Figure 4. is a top view of the structure shown in Figure 3, and Figure 5 is a longitudinal section of an electron discharge device and resonator and showing a modification of a resonator made according to my invention.

In Figure l is disclosed a resonator of the type under discussion and illustrates the principles involved.

This resonator comprises the hollow drumshaped member iii having flat end walls and a tubular outer or side wall and having within it the central cylindrical conducting member ll surrounded by the coaxial tubular collar l2. Positioned and extending between the collar I2 and the inside Wall of the hollow member lll is an annular tuning ring is movable axially of the resonator by means of rod it provided with handle M.

In effect the arrangement shown in Figures 1 and 2 comprises a pair of concentric annular resonators coupled together by the space between the inner end of collar l2 and the opposite end of the resonator. The inner resonator has the outer radius a, inner radius 0 and the axial length 3 and contributes inductance L,=2s log, x 1w henry The outer resonator has an outer radius 22, inner radius a, and variable axial length y. It contributes an inductance L =2y log, 3X 10' henry Hence, the total inductance is equal to L=2 E 10 %+y 10 i0- henry The range of variation is governed by the range of y. The range may also be controlled by varying the length of sleeve of radius a, and also by varying radius a.

In Figure 3 is shown an ultra high frequency oscillator in which the cavity resonator connected to the output of the tube incorporates the invention described above. In this arrangement I em.- ploy a triode of the type described in my copending application, Serial No. 516,388 filed December 31, 1943, now Patent No. 2,461,125, dated February 8, 1949, and assigned tothe same assignee as the present application. It comprises a cathode assembly 28 and an oppositely disposed anode 2! with an intermediate grid having a ring seal 22 extending through the envelope comprising the insulating portions 23 and 23, preferably of glass.

The cathode conductor and cathode heater leads comprise the outer tubular conductor 211 and the inner conductor 2 and the input cavity resonator is coupled between the cathode and the grid ring and includes the inner tubular member 25 and outer tubular member 2?, which together with shorting ring 28 form a coaxial line cavity resonator. The outer tubular conductor 20 connected to the cathode is capacity coupled as shown to the inner tubular member 26. The 1 c n uctor 24, is connected to the cathode 3 heater and to lead 25, and the lead is connected to conductor 20. These leads serve as the cathode heater leads and as the cathode lead. Tuning is accomplished by means of the tuning handle 29 connected to the tuning shorting ring 28.

The output cavity resonator employing my invention is in the form of a hollow drum and includes the plate-like end wall member 30, an annular wall member 3| and top plate end wall, member 32 insulated from wall member 3! by means of the insulating ring 33, preferably of mica. The anode 2! is provided with a coupling flange 2! clamped to the'wall member 32 by means of the clamp 36. Within the resonator is a collar element 35, and between the collar element and the wall member 3| is movably mounted a tunable shorting ring 35 operated by means of handle 3?. As described above this resonator may be tuned to vary its resonant frequency by moving the ring 38.

A variation of the arrangement shown in Figures 3 and a is shown in Figure 5. Here the two communicating portions of the cavity resonator are formed by means of sylphon bellows 4c and 40' within the tubular wall 3! and having different diameters and connected by the conducting ring 41 cooperating with adjusting screws 42 and {53. By operation of these adjusting screws the different diameter portions may be simultaneously adjusted in relative axial length by moving the ring 4! axially within the resonator, to vary the resonant frequency of the resonator. The smaller bellows 40 corresponds to the tubular collars l2 and 35 of Figs. 1 and 3 wherein the axial length of the collar is adjustable.

Thus with the arrangement described above I accomplish all the purposes set forth above and. provide a triode amplifier or oscillator which may be tuned over a comparatively wide range.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

- 1. An electron discharge device having a cathode, grid and an anode, a coaxial line resonator coupled between said grid and said cathode, and means extending between the walls of said resonator for tuning said resonator, and a drumshaped second resonator coupled between said grid and anode and having a surface of revolution and having wall portions of different diameter surrounding a portion of said electron discharge device, the ends of said electron discharge device extending beyond the ends of said drumshaped resonator, and movable means contacting the walls of said second resonator for varying the effective axial length of one of said wall portions to vary the resonant frequency of said sec- 0nd resonator, both of said wall portions of said second resonator being spaced laterally from said electron discharge device.

2. An electron discharge device having a cathode, grid and an anode, a coaxial line resonator coupled between said grid and said cathode, and a drum-shaped second resonator coupled between said grid and anode and having a surface of revolution and having wall portions of different diameter surrounding a portion of said electron discharge device, the ends of said electron discharge device extending beyond the ends of said second resonator, and movable means contacting the walls of said second resonator for varying the relative effective axial lengths of said wall portions to vary the resonant frequency of said second resonator, both of said wall portions of said second resonator bein spaced laterally from said electron discharge device.

3. An electron discharge device havin a cathode, grid and anode, a coaxial line resonator coupled between said grid and said cathode, and a second resonator coupled between said grid and anode, said second cavity resonator including a drum-shaped hollow member surrounding said electron discharge device and having within it a collar member coaxial with the axis of revolution of said drum-shaped member and extending from one end thereof and positioned between and spaced from the electron discharge device and the outer wall of said second cavity resonator, and a ring element extending between said collar member and the inside surface of said drum-shaped member and movable axially to vary the resonant frequency of said second cavity resonator.

4. An electron discharge device having a cathode, grid and anode, a coaxial line resonator coupled between said grid and said cathode, means within said resonator for tuning said resonator, and a second cavity resonator coupled between said grid and anode, said second cavity resonator including a drum-shaped hollow member having within it a collar member coaxial with the axis of revolution of said drum-shaped member and extending from one end thereof and spaced from said election discharge device, and a tuning ring extending between said collar member and the inside surface of said drum member and movable axially to vary the resonant frequency of said second cavity resonator.

5. An electron discharge device having a cathode, grid and an anode, a coaxial line resonator coupled between said grid and said cathode, and a second resonator coupled between said grid and anode, the outer wall of said second resonator including two connected bellows of different diameter, andmeans for varying the relative lengths of said bellows.

6. An electron discharge device having a cathode, grid and an anode, a coaxial line resonator coupled between said grid and said cathode, and a second resonator coupled between said grid and anode, said second resonator including a bellows of conducting material having portions at different diameters, a fixed ring, a first portion of one diameter coupled to said ring and a second portion of another diameter coupled to the opposite side of said ring, and means for fixing the ends of said portions opposite the ends fixed to said ring, and means for moving said ring to vary the relative lengths of the portions of different diameters.

'7. A cavity resonator including a substantially drum-shaped hollow member having end walls, a tubular member extending from the inner surface of one of said end walls into said hollow member and coaxial with the axis of rotation of said drum-shaped member, and movable means extending between said tubular member and the inside surface of the wall of said hollow member surrounding said tubular member whereby the space within said hollow member opening into the interior of said tubular member may be varied to vary the resonant frequency of said resonator.

8. A cavity resonator including a substantially drum-shaped hollow member having end walls, a tubular member extending from the inner surface of one of said end walls into said hollow member but spaced from the other end wall of said hollow member, and an annular conducting member extending between said tubular member and the wall of said hollow member surrounding said tubular member and movable for varying the outer space within said hollow member which opens into the interior of said tubular member to vary the resonant frequency of said resonator.

9. A cavity resonator comprising a drumshaped member having end walls, a, tubular member within said drum-shaped member coaxial with the axis of rotation of said drum-shaped member and supported from one of said end walls and extending axially of and within said drumshaped member but spaced from the other end wall of said drum-shaped member, and a conductor extending along the axis of rotation and coaxial with said tubular member and extending beyond the free end of said tubular member, a ring element mounted in the space between the inner surface of the wall of the drum-shaped member surrounding said tubular wall and the tubular wall and movable longitudinally of the drum-shaped member to vary the frequency of said resonator.

10. An electron discharge device having a grid and an anode, and a drum-shaped cavity resonator surrounding said grid and said anode, said r resonator comprising a pair of end walls each connected for high frequency currents to one of said grid and said anode, an outer tubular wall connecting the outer edges of said end walls, an

inner tubular wall extending axially from one of said end walls toward but spaced from the other end wall and positioned between and spaced from said outer wall and said device, said resonator walls providing two communicating resonator portions, and axially-movable means extending between said inner and outer tubular walls for varying the axial length of one of said resonator portions to vary the resonant frequency of said resonator.

11. An electron discharge device having a cathode, grid and anode, and a drum-shaped cavity resonator surroundin said grid and said anode, said resonator comprising a pair of end. walls each connected for high frequency currents to one of said grid and said anode, said grid and the end wall coupled to said grid shielding said cathode from said anode, an outer tubular wall connecting the outer edges of said end walls, an inner tubular wall extending axially from one of said end walls toward but spaced from the other end wall and positioned between and spaced from said outer wall and said device and providing two communicating cavity resonator portions, and axially-movable means extending between said tubular walls for varyin the axial length of one of said resonator portions to vary the resonant frequency of said resonator.

12. A cavity resonator comprising a substantially drum-shaped conductin member having end walls, a tubular outer wall, a tubular partition extending coaxially from one of said end walls into said hollow member toward but spaced from the other end wall and providing two concentric communicating annular cavity resonator portions of diiTerent outer diameters, and axially- 6 movable means extending between said tubular member and said outer wall, whereby the volume of at least one of said resonator portions may be varied to vary the resonant frequency of said resonator.

13. A cavity resonator including a substantially drum-shaped hollow member having end walls and a tubular outer wall, at least one of said end walls having an axial aperture adapted to receive an electron discharge device therein, a tubular member extending from the inner surface of said apertured end wall into said hollow member and positioned between and spaced from said aperture and said outer wall and coaxial therewith, and axially-movable means extending between said tubular member and said outer wall whereby the space within said hollow member may be varied to vary the resonant frequency of said resonator.

14. A cavity resonator including a substantially drum-shaped hollow member having end walls and a tubular outer wall, at least one of said end walls having an axial aperture adapted to receive an electron discharge device therein, a tubular member extending from the inner surface of said apertured end wall into said hollow member but out of contact with the other end wall and positioned between and spaced from said aperture and said outer wall and coaxial therewith, and axially-movable means extendin between said tubular member and said outer wall whereby the space within. said hollow member may be varied to vary the resonant frequency of said resonator.

15. A cavity resonator including a substantially drum-shaped hollow member having end walls and a tubular outer wall, each of said end walls having an axial aperture adapted to receive an electron discharge device therein, a tubular member extending from the inner surface of one of said end walls into said hollow member and positioned between and spaced from. said outer wall and the aperture in said one end wall and coaxial therewith, and axially-movable means extending between said tubular member and said outer wall whereby the space within said hollow member may be varied to vary the resonant frequency of said resonator.

16. A cavity resonator including a substantially drum-shaped hollow member having end walls and a tubular outer wall, each of said end walls having an axial aperture adapted to receive an electron discharge device therein, a tubular member extending from the inner surface of one of said end walls into said hollow member but out of contact with the other end wall and positioned between and spaced from the outer wall and the aperture in said one end wall and coaxial therewith, and axially-movable means extending between said tubular member and said outer Wall whereby the space within said hollow member may be varied to vary the resonant frequency of said resonator.

17. A cavity resonator including a substantially drum-shaped hollow member having end walls and a tubular outer wall, a tubular bellows extending coaxially from one of said end walls into said hollow member, and movable means attached to the free end of said bellows and extending between said bellows and said outer wall, whereby the space within said hollow member may be varied to vary the resonant frequency of said resonator.

18. A cavity resonator including a substantially drum-shaped hollow member having end walls, a pair of tubular bellows of difierent diameter 7 extending coaxially from opposite end walls into said hollow member, and movable means connecting the free ends of said bellows, whereby the space within said hollow member may be varied to vary the resonant frequency of said resonator.

LEON S. NERGAARD.

REFERENCES CITED Number 8 UNITED STATES PATENTS Name Date Dallenbach July 25, 1939 Llewellyn Feb. 20, 1940 Linder Feb. 25, 1941 Goldstine Feb, 29, 1944 McArthur July 18, 1944 Haefl. May 21, 1946 Wagner July 16, 1946 Gurewitsch Oct. 8, 1946 Gurewitseh Nov. 19, 1946 Gurewitsch June 22, 1948

Images