US3286125A

US3286125A - Radio frequency apparatus

Info

Publication number: US3286125A
Application number: US153425A
Authority: US
Inventors: Richard G Lock
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1961-11-20
Filing date: 1961-11-20
Publication date: 1966-11-15
Anticipated expiration: 1983-11-15

Description

Nov. 15, 1966 R. G. LOCK 3,286,125

RADIO FREQUENCY APPARATUS Filed Nov. 20, 1961 2 Sheets-Sheet 1 FIG.5.

INVENTORI RICHARD G. LOCK,

HIS ATTORNEY.

NOV. 15, 1966 LOCK 3,286,125

RADIO FREQUENCY APPARATUS Filed Nov. 20, 1961 2 Sheets-Sheet 2 FIGZJ INVENTORI RICHARD G. LOCK BWW HIS ATTORNEY.

United States Patent RADIO FREQUENCY APPARATUS Richard G. Lock, Albany, N.Y., asslgnor to General Electric Company, a corporation of New York Filed Nov. 20, 1961, Ser. No. 153,425 4 Claims. (Cl. 31539.63)

My invention relates to improved interdigital magnetron devices which are particularly adapted for anode voltage tuning and to improved radio frequency apparatus incorporating such devices.

A magnetron is a microwave device employing crossed electric and magnetic fields between concentrically arranged electrodes. In the case of interdigital voltage tunable magnetrons, the types, for example, disclosed and claimed in US. Patents Nos. 2,810,095 and 2,810,096 of P. H. Peters, Jr., et al., issued October 15, 1957, and assigned to the same assignee as the present invention, the anode comprises a plurality of interdigital segments and adjacent segments are connected alternately to two axially spaced terminals sealed in the envelopes of the devices. For 71' modeoperation of this type of device, each terminal is a radio frequency equipotential and it is usually des'irable to connect these two terminals directly to a transmission line by mounting the tube directly in theline,

One such form of apparatus is disclosed and claimed in U.S. Patent No. 2,940,007 of H. L. Thal, Jr., issued June 7, 1960, and also assigned to the same assignee as the present invention. This form of apparatus provides for a RF. transformer, or transition, section between the device and a coaxial line and generally requires for high frequency operation at least some form of auxiliary R.F. shielding structure to avoid undesired radiation. It is desirable to provide an interdigital tube structure and RF. apparatus which enables a direct connection between a coaxial, or other form of unbalanced transmission line, thereby to avoid the necessity for a transition section between the tube and line. Also, it is desirable that the circuit comprises a closed structure thereby to prevent RF. radiation and to obviate the need for auxiliary RF. shielding. Coaxial contact arrangements coextensive with the longitudinal axis of the tube have been suggested. However, this form of structure can introduce undesired coupling with the cathode assembly which generally includes a nonemissive cathode, an electron emitter, and control means. Also, this form of structure usually is provided with DC. contacts at either or both ends of the magnetron and can interfere with the location and close spacing of magnet pole pieces required to provide an operating magnetic field extending coaxially through the device.

The present invention contemplates a new and improved interdigital magnetron structure and RF. apparatus incorporating such a structure and which is noncoaxial with respect to the magnetron and is adapted for providing a closed structure effective to minimize R.F. radiation, to obviate the need for auxiliary shielding structure to avoid undesirable coupling with the cathode assembly and to avoid interference with the positioning and spacing of the operating magnet pole pieces.

Accordingly, the primary object of my invention is to provide a new and improved interdigital magnetron device which is particularly adapted for direct connection to an unbalanced transmission line.

Another object of my invention is to provide a new and improved interdigital magnetron device and new and improved R.F. circuit apparatus particularly adapted for incorporating such a device.

Another object of my invention is to provide a new and improved interdigital magnetron device and.R.F. circuit apparatus adapted for enabling direct connection between the magnetron and an unbalanced transmission line and which obviates the need for auxiliary R.F. shielding structure. I

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out without particularity in the claims annexed to, and forming part of this specification.

In carrying out the objects of my invention I provide an interdigital magnetron comprising an envelope having three ringeshaped anode terminals sealed in axially spaced relation in the wall of the envelope. Provided in the envelope is an annular interaction region defined by an elongated centrally-disposed nonemissive cathode and a plurality of interdigital anode segments arranged in a cylindrical array. The anode segments comprise two sets of alternate segments Thesegments of one set are connected between and are supported by the outer two of the aforementioned three axially spaced anode terminals. The segments of the other set are connected and are supported by the intermediate anode terminal. An electron emitter and control means therefor are provided in the device at a location axially displaced from the interaction region and are adapted for directing electrons into the interaction region. Provided for cooperating with the device is an RF. output circuit comprising an unbalanced transmission line of either the coaxial type or the type including a single conductor between two parallel planes. In this apparatus the inner conductor is directly connected to the intermediateanode terminal and opposed sides of the outer conductor of the coaxial line, or the two outer planar conductors of the wire between two planes type of line, if the latter is being used, are directly connected to both of the outer anode terminals. In one form of the invention, the opposed sides of the outer conductor of the coaxial line, or the two outer planar conductors of the wire between two planes type of line, are apertured to include registering openings to receive the ends of the device and make circumferential contact to both outer anode terminals. This arrangement provides a closed structure to prevent R.F. radiation. Additionally, in this form of structure a tuning element can be slidably positionable in an extension of the line and connecting the conductors on one side of the device.

For a better understanding of my invention reference may be had to the accompanying drawing in which:

FIGURE 1 is an enlarged sectionalview of an interdigital magnetron device embodying my invention;

FIGURE 2 is a fragmentary exploded perspective view illustrating a manner of constructing the anode assembly incorporated in the device illustrated in FIGURE 1;

FIGURE 3 is a fragmentary view illustrating R.F. apparatus including my improved magnetron device and a coaxial line R.F. output;

FIGURE 4 is a fragmentary view illustrating R.F. .apparatus including my improved magnetron device and a wire between two planes type of line output circuit;

FIGURE is a fragmentary partially sectionalized view of RF. apparatus incorporating my improved magnetron device and comprising a coaxial line R.F. output circuit and tuning means; and

FIGURE 6 is a fragmentary partially sectionalized view of RF. apparatus incorporating my improved magnetron device and comprising wire between two planes type of RF. output circuit and tuning means.

Referring to the drawing, there is shown in FIGURE 1 a magnetron device embodying a form of my invention and generally designated 1. The device 1 includes an envelope generally designated 2 and constituted of a stacked assembly of alternately arranged metal and ceramic members wherein the metal members serve as electrical contacts'or terminals of the device and the ceramic members serve as insulative wall sections and spacers between the metal members. The mentioned metal members include three ring-shaped anode terminals 3-5 separated by a pair of ceramic cylinders 6 of equal lengths. The metal members further include a frusto -conical control electrode 7 which includes a flanged, or annular, section 8 separated from the anode terminal 3 by a cylindrical ceramic member 9.

The envelope 2 is completed by a pair of end ceramic members 10 and 11 and a pair of

metal end caps

12 and 13. The elements described to this point are suitably bonded together to provide a hermetically sealed evacuated envelope.

The end cap 13 carries a metal post 14 which comprises a cold, or non-emitting, cathode extending coaxially in the envelope to a point just'inwardly of the inner end of the control electrode 7. The end cap 12 carries a coaxial boss 15 on which is mounted one end of a helical emitter 16. The other end of the emitter 16 is supported on and makes electrical contact with the inner end of the cold cathode 14. In this arrangement the end caps 12 and 13 serve as DC. cathode contacts for opposite ends of the emitter 16. This construction of the cold cathode and emitter are substantially identical to those disclosed in the aforementioned Patents Nos. 2,810,095 and 2,810,096. However, it is to be understood that this manner of cathode construction is not required for operation of my presently disclosed invention. My invention is applicable to interdigital magnetron devices including other forms of cathode constructions such, for example, as the cathode construction disclosed and claimed in US. Patent No. 2,930,933 of G. J. Griffin, Jr. et al. issued March 29, 1961 and assigned to the same assignee as the present invention and which incorporates an emissive cathjode mounted from a single end of the tube envelope. Also, my invention is not limited to directly-heated cathode structures but can incorporate indirectly-heated emitters of the type disclosed and claimed, for example, in US. Patent No. 2,997,624 of P. H, Peters, Jr., issued August 22, 1961 and assigned to the same assignee as the present invention. 7

As seen in FIGURES 1 and 2, the present device is of the interdigital type and the anode terminals support within the envelope 2 an anode assembly including two sets of axially extending anode segments alternately arranged in a cylindrical array and supported concentrically in the envelope by the anode terminals 3-5. More specifically, alternate segments, or the segments of one set of alternate segments, are bail-like in construction and are conductively connected to and supported by the inner rim portions of the two outer anode terminals 3 and 5. The other segments 18, or the segments of the other set of alternate segments, are straight elongated segments and are conductively connected at the midportions thereof to, and are supported by, the inner rim portion of the intermediate anode terminal 4. As seen in FIGURE 2, the one set of alternate segments of the just described anode assembly generally designated 17 can be conveniently provided by forming, as by bobbing, each of the outer anode terminals 3 and 5 to include a plurality of equally, circumferentially spaced and longitudinally extending L-shaped half-segments 19 which, when the device is assembled, are joined at the adjacent inner ends thereof to provide the above-mentioned bail-like segments 17 interconnecting the terminals 3 and 5. Also, the other set of segments 18 can be conveniently formed by constructing the inner anode terminal 4 of a pair of joined back-to-back rings with oppositely extending L- shaped half-segments 20 which, when the just-mentioned rings are joined together, form the equally, circumferentially spaced and generally T-shaped anode segments 18 extending interdigitally between the segments 17 carried by the anode terminals 3 and 5. The segments of the difierent sets are slightly separated circumferentially to provide axially extending interaction gaps. Also, the segments are slightly spaced radially from the cold cathode 14 to provide an annular space charge interaction region. As is well understood in the magnetron art, it is the interaction between the high frequency fields across thesegment gaps and the rotating and bunched space charge in the interaction region that effects the desired energy transfer from the space charge to the oscillatory circuit of the anode.' As is also well understood in the art, the electron rotation results from the provision of an operating magnetic field extending coaxially through the device. Such a field is usually provided by disposing the magnetron between opposed closely spaced pole pieces designated N and S of a magnet in the manner illustrated in the various figures in the drawing.

In the embodiment illustrated, the electrons constituting the rotating beam originate in the device at the emitter 16 which is longitudinally displaced relative to the interaction region defined by the cold cathode and anode segments, and the introduction or injection of the electrons into the interaction region is under control of the frusto-conical electrode 7. This feature of the disclosed structure does not constitute part of the present invention but is disclosed and claimed in the aforemen tioned Patent 2,810,096. In 'Ir-IllOdS operation of the above-described device, the outer anode terminals 3 and 5 are of the same R.F. potential and the inner terminal 4 is out of phase therewith. Thus, and as seen in FIGURES 3-6, the device 1 is particularly well adapted for having directly connected thereto an unbalanced transmission line of either the coaxial or wire between two planes types.

' In FIGURE 3 is illustrated an RF. apparatus, or voltage tunable magnetron R.F. apparatus, comprising a tube 1 "and a directly connected coaxial transmission line 21. In this apparatus the inner conductor 22 of the line 21 is directly connected to the inner anode terminal 4 and the outer conductor 23 which is cylindrical is directly connected to both of the outer anode rings 3 and 5 at diametrically opposed points on the end of the conductor 23. Thus, the connection between the device 1 and the output line 21 is eflected without the need for a transition section or a substantial open region which would require R.F. shielding at high frequencies.

The apparatus of FIGURE 4 is similar to that of FIGURE 3 except that in place of a coaxial transmission line, the RF. output circuit comprises wire between two planes type of line 24 specifically including spaced planar outer conductors 25 connected each to one of the outer anode terminals 3 and 5 of a device 1, and an intermediate spaced parallel inner conductor or wire 26 conductively connected to the inner anode terminal 4.

Illustrated in FIGURE 5 is apparatus incorporating a device 1 and a completely enclosed R.F. output circuit generally designated 27. In this embodiment the output circuit'comprises a coaxial line including an inner conductor 28 and a tubular outer conductor 29. The inner conductor 28 is in two sections with each section conductively connected to the intermediate anode terminal 4 on an opposite side of the. device 2. The outer conductor 29 includes a cylindrical section 30 and a generally flat tened tubular transition section 31. The flattened section 31 has opposed planar walls or sides which are generally coextensive with the anode terminals 3 and 5 and are formed to include a pair of opposed registering apertures 32. The device 1 is positioned in the section 31 and the lowermost anode terminal 5 is seated in an annular recess 33 formed on the inner surface of the lower side of th section 31 and so as to be concentric with the aperture 32. Thus, the lower side of the section 31 makes circumferential conductive contact with the anode terminal 5. The uppermost anode terminal 3 is generally coplanar with the upper side of the section 31 and a retaining ring 34 is provided for holding the device 1 securely positioned in the section 31 with the anode ring 3 making suitable circumferential contact with the upper side of the section 31. In this manner I have provided an apparatus including an RF. output which is completely enclosed by conductive material and, thus, is not subject to undesired R.F. radiation. This renders the described structure particularly effective for high frequency applications where R.F. shielding is generally required.

As also seen in FIGURE 5, the section 31 comprises a tubular functional region generally designated 35 located opposite the output region 27. Region 35 contains one section, or a continuation, of the center conductor 28. Also, ahe region 35 can contain an element or stub 36 slidably fitted over the center conductor and connecting the center conductor and the outer conductor. The element 36 can be provided with a handle 36a and is adapted for being used for adjustably resonating the apparatus at predetermined desired operating frequencies.

Illustrated in FIGURE 6 is apparatus including a device 1 and a partially closed R.F. output circuit generally designated 37. In this embodiment the RF. output comprises a section of wire between two planes type of line 38 and includes a pair of spaced parallel planar outer conductors 39 and a spaced parallel inner conductor or wire 40. The inner conductor 40 is in two sections each conductively coupled directly to one side of the inner anode ring 4 and the outer conductors 39 include a section wherein the conductors are formed with registering apertures 41. The device 1 is positioned in the apertured section and the lowermost terminal 5 is seated in an annular recess 42 formed on the inner surface of the lower one of the planar conductors 39, and thus makes circumferential conductive contact therewith. The uppermost anode terminal 3 is generally coplanar with the upper one of the planar conductors 39 and a retaining ring 43 is effective for holding the device in one position securely in the apparatus with the anode ring 3 making suitable circumferential conductive contact with the upper conductor of the line 38. Thus, is provided apparatus including an RF. output which has opposed planar conductors both at the same R.F. potential and serving to provide some measure of RF. shielding and minimize the amount of shielding required to insure against undesired R.F. radiation.

The embodiment of FIGURE 6 is also adapted for adjustable tuning. Specifically, and as seen in FIGURE 6, the the line 38 includes a functional region generally designated 44 disposed on the side of the device 1 opposite the RR output. In the region 44 there is provided a stub or element 45 which is slidable over the center conductor 40 and interconnects the center and outer conductors. Additionally, the element 45 is provided with a handle 45a and is adjustably positionable relative to the device 1 for thereby adjustably resonating the circuit at predetermined desired operating frequencies.

While I have shown and discussed specific embodiments of my invention, I do not desire my invention to be limited to the particular forms shown and described, and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Radio frequency apparatus comprising an electric discharge device including an envelope, an interaction structure contained in said envelope including a negative central electrode and a surrounding cylindrical array of circumferentially spaced anode segments, three axially spaced anode terminals sealed in the wall of said envelope with alternate ones of said anode segments connected to the outer two of said terminals and the others of said segments connected to the intermediate one of said terminals and a radio frequency output transmission line comprising a central conductor coupled to said intermediate terminal and outer conductive means coupled to both said outer anode terminals, said transmission line includes an output section and a tuning section located on opposite sides of said device and said tuning section includes an element interconnecting the central conductor and outer conductive means and is adjustably positionable for selectively adjustably resonating said apparatus.

2. Radio frequency apparatus comprising an electric discharge device including an envelope, an interaction structure contained in said envelope including a negative central electrode and a surrounding array of circumferentially spaced anode segments, three axially spaced ringshaped anode terminals sealed in the wall of said envelope with alternate ones of said anode segments connected to the outer two of said terminals and the others of said segments connected to the intermediate one of said terminals, and a radio frequency transmission line comprising an output section including an inner conductor and a pair of oppositely disposed planar conductive sections extending in spaced parallel relation to said inner conductor, said inner conductor being coupled to said intermediate terminal, and each said planar conductor being apertured and having rim portions thereof making circumferential electrical contact with one of said outer terminals of said device, said transmission line including a section extending on the side of said device opposite said output section and further including an element conductively interconmeeting the inner and planar conductors and slidably positionable for selectively adjustably resonating said apparatus.

3. Radio frequency apparatus comprising an electric discharge device including an envelope, an interaction struc ture contained in said envelope including a negative central electrode and a surrounding cylindrical array of circumferentially spaced anode segments, three ring-shaped axially spaced anode terminals sealed in the wall of said envelope with alternate ones of said anode segments connected to the outer two of said terminals and the other of said segments connected to the intermediate one of said terminals, and -a coaxial transmission line comprising an output section including a center conductor and a tubular outer conductor having a cylindrical section extending parallel to said center conductor and a section having opposed planar walls, said center conductor being 'coupled to said intermediate terminal, said opposed planar walls of said outer conductor each being apertured and having a rim portion thereof coupled to one of said outer terminals of said device, said transmission line including a tuning section located opposite said output section and containing an element conductively interconnecting said inner and outer conductors and adjustably positionable for selectively adjustably resonating said apparatus.

4. An interdigital anode assembly comprising in combination,

(a) a central anode ring assembly,

(b) said central anode ring assembly consisting of two planar rings each of which have axially extending segments therefrom in one direction,

(c) said rings being placed in abutting back-to-back References Cited by the Examiner UNITED STATES PATENTS Nordsieck 315--39.73 X Ludi 31539.73 X

Peters 315-3913 McLaughlin 31539.73

HERMAN KARL SAALBACH, Primary Examiner. Q ARTHUR GAUSS, Examiner.

S. CHATMON, JR., Assistant Examiner.

Claims

1. RADIO FREQUENCY APPARATUS COMPRISING AN ELECTRIC DISCHARGE DEVICE INCLUDING AN ENVELOPE, AN INTERACTION STRUCTURE CONTAINED IN SAID ENVELOPE INCLUDING A NEGATIVE CENTRAL ELECTRODE AND A SURROUNDING CYLINDRICAL ARRAY OF CIRCUMFERENTIALLY SPACED ANODE SEGMENTS, THREE AXIALLY SPACED ANODE TERMINALS SEALED IN THE WALL OF SAID ENVELOPE WITH ALTERNATE ONES OF SAID ANODE SEGMENTS CONNECTED TO THE OUTER TWO OF SAID TERMINALS AND THE OTHERS OF SAID SEGMENTS CONNECTED TO THE INTERMEDIATE ONE OF SAID TERMINALS, AND A RADIO FREQUENCY OUTPUT TRANSMISSION LINE COMPRISING A CENTRAL CONDUCTOR COUPLED TO SAID INTERMEDIATE TERMINAL AND OUTER CONDUCTIVE MEANS COUPLED TO BOTH SAID OUTER ANODE TERMINALS, SAID TRANSMISSION LINE INCLUDES AN OUTPUT SECTION AND A TUNING SECTION LOCATED ON OPPOSITE SIDES OF SAID DEVICE AND SAID TUNING SECTION INCLUDES AN ELEMENT INTERCONNECTING THE CENTRAL CONDUCTOR AND OUTER CONDUCTIVE MEANS AND IS ADJUSTABLY POSITIONABLE FOR SELECTIVELY ADJUSTABLY RESONATING SAID APPARATUS.