US2666165A

US2666165A - Tunable magnetron oscillator

Info

Publication number: US2666165A
Application number: US638883A
Authority: US
Inventors: Hutchinson Franklin
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-01-03
Filing date: 1946-01-03
Publication date: 1954-01-12
Anticipated expiration: 1971-01-12

Description

Jan. 12, 1954 F. HUTCHINSON 2,666,165 TUNABLE MAGNETRON OSCILLATOR Filed Jan. 3, 1946 ISM \ l7 K p 7 rN/i?! -5 6 A0 I0 I j INVENTOR FRANKLIN HUTCHINSON BY ATTORNEY Fate-med Jan. 12, 1954 TUNABLE MAGNETRON OSCILLATOR Franklin Hutchinson, New Haven, Conn, assignor, by mesne assignments, to the United States of America. as represented by the Secretary of War Application January 3, 1946, Serial No. 638,883 r 7 Claims. (01. 315-40) My invention relates in general to electrical apparatu and more particularlyto magnetron oscillators.

In the art of ultra-high frequency and mlcro- Wave energy generation by means of magnetron oscillators it is often desirable to couple auxiliary resonant devices to a magnetron in order to effect stabilization of, or controlled alteration in, the fre uency of the generated oscillations. Where the individual resonators of a multi-cavity magnetron are strapped together, as is frequently the case, it is possible to couple external apparatus very tightly to the magnetron through the straps.

Previously, such coupling has always necessitated mechanical attachment of one or more leads to the straps of the magnetron. If the points of attachment are not symmetrically located on the straps, it has been found that angular distortion of the radio-frequency fields in the electronic interaction space results, with possible impairment of performance. Furthermore, in the upper rang of frequencies in use at the present time it becomes increasingly difiicult to make lead connections to the straps because of the extremely small dimensions of the magnetron components.

Accordingly, it is one object of my invention to provide means of coupling to a magnetron.

Another object is to provide means of symmetrically coupling to a strapped magnetron.

Still another object is to provide a readily adjustabl means of coupling to a magnetron.

Yet another object is to provide means of coupling to the straps of a magnetron without making mechanical attachments to the straps.

A further object is to provide a tunable magnetron oscillator.

A still further object is to provide a novel tuning or stabilization cavity for a magnetron oscillator.

Briefly, my invention accomplishes these and other objects which will be apparent to those skilled in the art by utilizing capacitive coupling between the magnetron straps and a disk-like member aligned in a plane parallel thereto. A rod attached to the disk passes into a cavity resonator constructed within one of the pole pieces of the magentron magnet. A coaxial line composed of the rod and the pole piece connects the resonator and the disk.

The principles and operation of my invention will be more apparent upon reference to the following specification, claims, and to the drawing, the single figure of which represents a cross- 2 sectional view of a magnetron and tuning apparatus therefor.

Referring now to this figure, a standard multicavity magnetron anode 5 and cathode 6 are shown. Anode 5 is double-strapped at both ends with

rings

7, 8, 5, and Ill. The magnetic field for the magnetron is supplied by a magnet the pole pieces l2 and 13 of Which are shown. Pol piece I3 is hollowed. out to form a cavity resonator l4 and a sliding plug [5 is inserted therein. A rod It extends through plug l5, being supported by th plug and by a glass member ll which is not sealed to the rod it but is sealed to a sleeve I8, the latter being preferably of the alloy known by the trade name Kovar, and which in turn is seated in pole piece l3. Rod [6, then passes through a hole l9 bored in pole piece l3 and at the extremityof the rod is attached a circular plate 26, the periphery of which extends farther toward the magnetron straps than does the center. .The disk is substantially the diameter of strap 8.

In the operation of the device the inherent capacity between strap 8 and plate 20 couple oscillatory energy into the coaxial conductor formed by pole piece 13 and rod l6. Glass seal I! does not inhibit the passage of energy into resonant cavity I l, hence oscillations are set up therein. The resonant frequency of cavity I4 is readily adjusted by sliding plug l5 toward or away from the magnetron anode. Hence the magnetron may be tuned within a predetermined bands of frequencies. The degree of coupling between the resonant cavity and the magnetron is governed by the spacing between plate 20 and strap 8. This spacing may be varied by sliding rod l6 toward or away from the magnetron anode. This variability is valuable in practice since the degree of coupling can be held constant despite unavoidable variations in the dimensions of the Various parts of the assembly.

The cavity resonator I4 is not the only possible frequency determining means nor is a coaxial line necessary to conduct energy from disk 20. The auxiliary resonator may, for example, be a resonant section of transmission line or a cavity resonator external to the apparatus, and the connector may be a single wire directly attached to the energy pick-up means and run out through the side of the device. Indeed, it is feasible to use a pick-up other than disk-shaped, as long as there is suflicient capacity between strap 8 and th pick-up to provide adequate coupling. However, in practice a disk which may be spaced apart 3 from the strap between 0.005 and 0.020 inch has been found satisfactory.

It will be understood that what has been described hereinbefore is a preferred embodiment of my invention but adaptations and modifications may be made therein Without departure from the principles of my invention. 2581166,.1 claim all such modifications and adaptations as may fall fairly Within the spirit and. scope of the hereinafter appended claims.

What is claimed is:

1. In a magnetron oscillator a segmented anode electrode, at least one: strip of conducting material joining at least aportiorr-ofsaidranode' segments, a conducting memberin spaced rela tionship with respect to said anode electrode and.

which is movably positioned adjacentlto saidzcone ducting strip, said conducting member, being capacitively coupled to said conducting strip? a; cavity resonator, and means coupling said conducting member to: said cavity resonator whereby the frequency of oscillations created ir-rsaid'magnetron oscillator is determined by the resonant frequency of said cavity resonator.

2. In a magnetron oscillator a segmentedanode electrode, a ring-like conducting member joining at leasta portion of said anc'd-esegments; a-- movable circular conducting member of substantiaily the same diameter as said ring-like member in spaced relationship with respect to said anode. electrode: and which is positioned adjac ent to said ring-like member, a cavity res onator, and means coupling sai'd circular member to said cavity resonator whereby "the frequency' of oscillations generated by said magnetronoscillator is determined by: the resonantfrequency of said" cavity resonator;

3% Apparatus in accordance with claim 2 wherein in addition there is provided a magnet positioned adjacent to said anodeelectrode; one of the poles of said magnet'being chambered to form said cavity resonator.

4'. Apparatus in accordance with 0mm 2 further including means movableinto said cavityresonator for tuning said cavity resonator, therebyenabling the frequency of oscillation of" said magnetron to" be varied in a predetermined fashion;

5. A magnetron oscillator comprising a. segmented anode electrode, a. ring-like strap con- 7 Number Name Date 21631589 Dallenbaeh et a1. "a June 27, 1939" 2,233,166 Hahn Feb. 25,. I941" 2308,2135 Q Spencer Sept. 24', 1946 23408238 Sp'e'n'ce'r Sept. 24'', I946. 2,411,953? B'roW'n Dec. 31,1946 2,414,085 Hartman Jan. 14, I947 2,421,639 McArthur June 3, I947 214241496 Nelson July 22; 1947 2,466,060 Spencer Apr; 5", I949 2,466,765" Hartman Apr; I2, 1949 2,482,541" Hall etal Sept. 20", I949 2,542,399" Brown Feb. 20, I951,

4 nected to at least a portion of said anode segments, a disk-like member in spaced relationship with respect to said anode electrode, means movably positioning said disk-like member adjacent to said strap so that said disk-like member remains symmetrical to said strap throughout the entire range of? its movement and electrical changes insaid strap produce corresponding changes in said disk-like member through the capacity therebetween, a tunable cavity resonator, and means extending through a Wall of said cavity resonator coupling said cavity resonator only to:said disk-like member, said cavity resonator beingcompletely closed except for said coupling means extending therethrough.

6. In a magnetron oscillator, a segmented anode electrode}, a ring-like member joining at least a portion of said anode segments, a disklike member of substantially the same diameter as said ring-like member, said disk-like member being arranged concentrically with said ringf-like member and in spaced relationship with respect to said anode electrode, whereby electrical changes in said ring-like member are: transferred to saiddisk-like: member through: the inherent capacity therebetween a cavity res'0- na-tor, and meanscouplin'g said cavity resonator to said disk-lilac member; said cavity resonator being completely enclosed except-for an. opening for said coupling means; 7

7 The-magnetron oscillator defined in claim- 6, further including means m'ovable intosaid cavity resonator fortun'ingsai'd cavityresonator.

FRANKLIN HUTCHINSON- References Cited. in the file of this patent UNITED- PATENTS