US2849652A - Magnetron - Google Patents

Description

Aug. 26,

1958 K. STEIMEL MAGNETRON Filed April 26, 1954 3 Sheets-Sheet 1 INVENTOR. KA RL STE/P1 E 1 BY 'W? Aug. 26, 1958 K. STEIMEL 2,349,652

MAGNETRON Filed April 26, 1954 3 Sheets-Sheet 3 /y/1/ /l /fX 2 F/& ..9

INVENTOR.

KARL. STE/MEL United States 2,849,652 Patented Aug. 26, 1958 MAGNETRON Karl Steimel, Ulm (Danube), Germany, assignor to TelefunkenG. m.- b. H., Ulm (Danube), Germany Application April 26, 1954, SerialNo. 425,584 Claims priority, application Germany April 24', 1953 20 Claims. (Cl; SIS-39.75)

The present invention relates to. a new and improved short wave, cavity resonator type magnetron.

There are known in the prior art magnetrons which have four anode segments and in which the individual segments form a bridge circuit having two mutually decoupled resonant circuits. These magnetrons operate at relatively long wavelengths. One of these well known arrangements may be illustrated by a circuit similar to the one shown in Fig. 2. Here, the inductive portions ofthe tuned circuits are shown as inductive elementsand the circuit capacitances shown as the distributed capacitances between adjacent anode sections. They also may be actual elements of an external tuned circuit.

Because of the decoupling of the separate tuned circuits in the arrangement above, the magnetron may be employed as a separately excited amplifier or may be operated as a frequency stabilized wave generator. However, the range of this prior art magnetron is limited. It is not, for example,suitable for use at ultrashort wave lengths;

It is an object of the present invention to provide a means for operating the conventional ultrashort wave magnetrons in the ultrashort wave region while retaining the advantageous features of the above-described prior art magnetrons.

In accordance. with the invention, there is provided a magnetron comprising a cathode and aplurality of cavity resonators symmetrically disposed about the cathode, each having an open end. facing the cathode. The number of cavity resonators is equal to an integral-multiple of x, x being an integer greater than one. Means are provided coupled to at least some of the cavity resonators for causing immediately succeeding groups, each consisting. of x adjacent resonators, to oscillate together as succeedingfirst units, forming together a first cavity resonator system. The above means aso causes immediately succeeding different groups, each consisting of x adjacent different ones of said resonators than comprise any first unit to oscillate together as immediately succeeding second units forming together a second cavity resonator system. In this arrangement, the first and second units overlap one another and are mutually electrically decoupled from one another.

In one preferred embodiment of the invention the magnetron comprises a vane-type magnetron and the vanes of like phase in atleast one of the systems of cavity resonators are strapped together. 1

In another preferred embodiment of the invention a first set of alternate vanes of the magnetron are maintained at a first predetermined direct potential and the remaining alternate vanes of the magnetron are maintained at a second predetermined direct. potential which is diiferent from the first predetermined direct potential.

In a third preferred embodiment of the invention the outer ends of a first set of alternate magnetron vanes are displaced in axial direction, that is toward one end of the cylindrical anode block and the outer. ends of another set of alternate vanes of the magnetron are dis 2 placed toward the other end of the cylindrical anode block. The result is the formation of two systems of cavity resonators which are mutually decoupled from one another and which have a relatively high Q.

Inany of the arrangements described above, by suitable arrangement or connection of anode vane elements it is possible to have two, three, oreven more adjacent cavity resonators operate together as a single unit.

Magnetrons constructed'in accordance with the invention can, as in the case of prior art magnetrons, either function as a separately excited amplifier or as a magnetron generator, the frequency of which is pulled into synchronization. In the last case, the proposed construction is of special importance when contrasted with the known arrangements. Up to the present time, in order to stabilize the frequency of a magnetron with a high Q device, it was necessary to provide an extremely short coupling circuit between the stabilizing device and one of: the cavity resonators of the magnetron. Although this did provide frequency stabilization of the magnetron, there was the disadvantage that even minor frequency variations caused abrupt jumps in the frequency output of the magnetron. This occurred in the known arrangements even though the coupling lead was extremely short, bec'ausethe two coupled resonant circuits had a multi wave property, and accordingly had a tendency to produce multi-moding. This tendency could" not be eliminated. The coupling loop could not be shortened because a given minimum couplingratio was required to permit the cavity resonator having a high Q to supply theconsiderable amount of reactive power needed by the cavity resonator of the magnetron. With the arrangement proposed in accordance with the present invention, it is now possible to eliminate the above difficulty. It is now possible to obtain a magnetron resonant cavity structure having an extremely high Q, even higher than is necessary for frequency stabilization-purposes, merely by thev coupling. between the electron stream and the high frequency energy in the magnetron cavities.

The novel features whichare considered as-characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both asto its construction and its method of operation, together with additional objects andadvantages thereof, will be best understood from the following description of specific embodiments when read in connectiorrwiththe accompanying drawings, in which:

Fig. Us a top view of a magnetron in accordance with the invention, with the end plate of the magnetron removed, showing schematically the high frequeney field distribution between different anode vane. sections;

Fig. 2 is an equivalent circuit of Fig. 1;

Fig. 3' is a top view, with an end plate removed, of a preferred embodiment of a magnetron in accordance with the: invention;

Fig. 4 is a cross-section along line AA of Fig. l; Fig. 5 is a top view, with an end plate removed, of anotherembodiment of a magnetron in accordance with the invention;

Fig. 6 is a cross-section along line BB of Fig. 5';

Fig. 7 is a cross-sectional view of another embodiment of a' magnetron in accordance with the invention;

Fig. 8 is a top view of a magnetron, with an end plate removed, showing the high frequency field distribution of an arrangement wherein each" oscillating unit comprises three adjacent cavity resonators;

Fig. 9 is a top view, with an end plate removed, of apractical embodimentcf a magnetron in accordance with the arrangement shown in Fig. 8; and' Fig. 10 is a crosssection along line (BC of Fig. 9.

Referring now to the drawing-and more particularly to Fig. 1 there is shown a vane-type magnetron having acylindrical anode 60 symmetrically disposed about a' cathode 9. Secured to the anode block and extending inwardly therefrom toward the cathode is a first plurality of alternate anode vanes 1-4 and a second plurality of alternate anode vanes -fi. Also provided is asymmetrical coupling loop 61 which passes through an aperture inanode vane 5 or anon-symmetrical coupling loop 62 which passes through an aperture in vane 3.

In operation, the first set of alternate anode vanes comprise a first system of cavity resonators, each of said cavity resonators consisting of the space defined by one of the vanes, for example, such as vane 1, the inner wall between that vane and the next adjacent vane such asinner wall portion 63, the walls of the adjacent vane such aswalls 64 and 65 ofvane 8, the inner wall portion of the anode block adjacent the last-named vane, such aswall portion 66, and the next adjacent vane such asvane 4. For the purposes of illustration, one of the cavity resonator units of the first system of cavity resonator systems is shown as a series of parallel lines betweenvanes 1 and 4. Succeeding units would comprise the spaces betweenvanes 1 and 2, 2 and 3, and 3 and 4. Also for the purposes of illustration, one of the cavity resonator units of the second system of cavity resonators is shown as the crossed lines extending betweenvanes 5 and 6. It is to be understood that as in the case of the first system, succeeding cavity resonator units exist betweenvanes 6 and 7, 7 and 8, and 8 and 9. It is easily seen from the above that the two systems of cavity resonators overlap one another.

In the arrangement described above the cathode structure 9 is illustrated schematically, however, it is to be understood that any type of cathode structure known in the magnetron art may be employed.

The equivalent circuit illustrated in Fig. 2 illustrates how the two cavity resonator systems are decoupled from one another. In this figure anode vanes of like phase are illustrated as a single segment; thus rather than showing eight anode segments the drawing shows only four segments. Thesegments 1, 2 correspond to vanes 1-4 and thesegments 5, 6' correspond to vanes 5-8. The resonant circuit inductance of the first system of cavity resonators is represented by inductance L and the resonant circuit inductance of the second cavity resonator system is represented by inductance L The distributed capacitance between vanes which comprises the resonant circuit capacitances is represented bycapacitances C 5,C 2,C 6, and C 1. From the equivalent circuit it is seen that the magnetron may be thought of as a bridge circuit in which segment pairs 1', 2' are decoupled from segments pairs 5', 6.

With the aid of the explanation above, it can be seen that the arrangement of Fig. 1 comprises two cavity resonator systems which are independent from one another and which both interact with the same electron stream. If during the operation of the magnetron, energy is taken from only one of the systems as, for example, in the case where only couplingloop 61 is used to supply an external load, the unloaded system has a frequency stabilizing effect on the loaded system because of the much higher Q of the unloaded system. In some embodiments of the invention actually constructed it has been found that the Q of the unloaded system, in general, is about ten times that of the loaded system.

As has already been mentioned, when it is desired to load a single one of the systems, an output coupling loop such as 61 (Fig. 1) may be employed. This loop passes through an aperture invane 5 and loads the first cavity resonator system, that is, the one in which cavity resonator units comprise the space between vanes 1-2, 2-3 etc. As illustrated, in a preferred embodiment of the invention coaxialcables couple loop 61 to the load. Of course, instead of coaxial cables, lecher lines may be employed or, in the case of higher frequencies, wave guides may be employed.

Instead of the balanced output arrangement, it is possible to use an unbalanced loop, such as 62 which is grounded at one end to the anode shell, in order to supply the output of the magnetron to a load. Here too, a coaxial line may be used to transmit the energy to the load orlecher lines, or a Wave guide according to the operating frequency.

In the arrangement of Fig. 1 only a single output means is necessary. If it is desired to load the first cavity resonator system (1-4) then a loop such as 61 is used and if it is desired to load the second cavity resonator system (5-8) then a loop such as 62 may be used. It is also possible to use both loops simultaneously in the case where it is desired to use one of the loops for an output load and the other of the loops as an input to the magnetron. In a preferred embodiment of the invention, for example, it may be desirable to supply a control oscillation throughloop 62 to the second oscillating system for purposes of frequency stabilization and to derive the output of the magnetron from the first cavity resonator system by means ofloop 61. In such case it is advantageous to so drive the magnetron that at least the unloaded system (the one which is driven from an external source) is not self-excited. In the event that the voltage fed to the unloaded cavity resonator system is a stabilizing oscillation the frequency of the oscillation is preferably the same as that of the output frequency of the magnetron. The stabilizing oscillation may be derived from a klystron or another magnetron oscillator.

In all of the cases above,'the electron stream interacts with the oscillating field of the unloaded cavity resonator system and becomes divided up into characteristic bunches, such as is familiar in velocity modulation devices, so that the electron stream appears to provide between the distributed capacitances of the loaded cavity resonator system a predetermined reactive component. However, the resonant frequency of the loaded cavity resonator system adjusts itself so that all reactive components mutually cancel one another. The electron stream also influences the resonant frequency of the resonators of the loaded system of cavity resonators. At the same time, in accordance with the known amplitude condition, the conductance created by the electron stream on the capacitive surfaces of the loaded system, which is negative, is equal to the actual distributed capacitance, which is positive, this last value including also the conductance of the load.

Figs. 3 and 4 illustrate an embodiment of the invention discussed above. It comprises a magnetron having acylindrical anode block 30, a first set of alternate vanes PSI-31c, and a second set of alternate vanes 32-320 Within the block is acathode 39 which is supplied throughleads 52 and 53. For simplicity of illustration these are not shown in Fig. 3. The set of vanes 31-31c are conductively connected to the anode shell and the remaining vanes 32420 are insulated from the shell by means of insulators 48-51, respectively. Vanes 32-32c are maintained at a potential ditferent from that of vanes 31-310 by means of a source of potential 45 which supplies direct voltage to the former vanes through leads 47.Capacitor 42, coil 43 and resistor 44 serve to filter out any high frequency energy and prevent the same from entering the direct voltage source.Strap 40 connects together vanes of a given like phase andstrap 41 connects together vanes of another like phase.Strap 40 is connected only to vanes 31 and 31b andstrap 41 is connected only tovanes 31a and 310. The output of the system may be obtained by thecoaxial line arrangement 46 the center conductor of which is connected to the inner strap and the outer conductor of which is connected to the outer strap. Theend plates 54 and 55 of the magnetron are illustrated in Fig. 4.

In operation of the embodiment of Figs. 3 and 4, the magnetron acts as two separate systems of cavity resona- 31 and 31a, 31a and 31b, 31b and 310, and 31c and 31,

and the second system comprising the spaces between 32 and 32a, 32a and 32b, 32band' 32c, and 32c and'32. As can readily be seen from the drawing, in this-embodiment the cavity resonator system defined by vanes 31-31c is the loaded system and the cavity resonators defined by the vanes 32-320 is the unloaded system. By proper selection of different vane potentials, it is possible to cause either one or both. of the two cavity resonator systems to oscillate as self-excited generator or generators. In a preferred embodiment of the invention, the source of potential 45 is accordingly made adjustable.

It is not necessary in the arrangement of Fig. 3 to use both straps and different vane potentials in order to ob-' tain theabove-described mode of magnetron operation. Ifdesired; only one of these methods may be employed. Also, if desired, a loop arrangement such as shown in Fig. 1 may be used as. the output coupling loop rather than the illustrated arrangement. Finally. it is to be understood that a control oscillation may be supplied to the unloaded cavity resonator in the same manner as explained in connection with Fig. 1.

Figs. 5 and 6 illustrate another embodiment of the invention. The magnetron comprises acathode 10, ananode cylinder 19 symmetrically disposed about the cathode and a plurality of vanes. 11-18 conductively connected to the anode cylinder and extending inwardly toward the cathode. As in. the previous embodiments, vanes 1114. define a first system of cavity resonators and vanes. 15-18 define. a second system of cavity resonators. Here, unlike the previously described embodiments, the ends of the vanes conductively secured to the anode. cylinder 19- are, displaced in axial direction of the cylinder from one another. Thus the set of vanes 11-14 are displaced toward the left end of the anode cylinder (Fig. 6) and the set of'vanes 15-18. are displaced toward the right end. of the anode cylinder (Fig. 6). The inner. ends of the vanes are aligned with one another andlie in an imaginary narrow cylindrical surface.

In operation of the embodiment shown in Figs. 5 and 6, the circular high frequency currentsin each of the systems of cavity resonators do not pass over, to any substantial degree, the vanes of. the other. system of cavity resonators. For this reason, the loss of energy isgreatly decreased. In this arrangement it is very. easy to obtain the required difierences in Qs betweenloaded and unloaded cavity resonator. systems, the usual. Q for the unloaded system of cavity resonators being about 1,500 and for the loaded system of cavity resonators about 150, giving a ratio of 10:1.

In order to change the tuning of the magnetron it is possible to utilize tuning equipment which may, for ex-' ample, make. use of the skin eifect principle and which does not otherwise disturb the above set forth, desirable mode of operation.

Fig. 7 illustrates schematically one preferred type of tuning arrangement which may be employed. As in the embodiment of Figs. 5 and 6, thevanes 11, 13, are displaced in axial direction of the cylinder from thevanes 17, 18. In order to effect the tuning of the system two rings 20-, 21', which are shown in section in Fig. 7, are employed. These rings may be moved toward or away from the respective cavity resonator systems by means of mechanical shafts S, S, respectively, which serve to movemembranes 22, 23, respectively, in the magnetron housing, therings 20, 21 being held on said membranes bystuds 67, 68., respectively.

Tuning arrangements such as described above are essential if it is desired to have the magnetron operate over abroad frequency band. In the event that an especially high Q is desired for the unloaded system, this may be obtained by increasing the surface conductivity of the. cavity resonators forming the unloaded cavity resonator CLO system as, for example, by plating the walls of the cavity resonators with silver as at X.

Fig. 8 illustrates a multiple cavity vane type magnetron for the purposes of explanation which includes three'cavity resonator systems which are mutually decoupled from one another. For the sake of illustration, the vanes defining the resonators of different systems are cross hatched differently. The first set of cavity resonators, is defined by vanes 25' -25;,; the second set of cavity resonators is defined by vanes 26 -26 and the third set of cavity resonators is defined by the vanes 27 -27 In order to illustrate how the fliree different cavity resonator systems are electrically decoupled from one another, the field distribution pattern of cavity resonator system 25 is illustrated in part by the dashed line and arrows. Beginning at vane 25 it is seen that the current path is from thisvane to vane 25 then along the inner wall ofanode cylinder 24 tovane 26,, over both surfaces ofvane 26 along the inner wall of the anode cylinder, over both surfaces ofvane 27 and then along the inner wall of the anode cylinder back to vane 25 A similar current path may be traced from the. other side of vane 25 to vane 25;, and back overvanes 27 and 26 to.25 A similar analysis can be made for the cavity resonator systems defined byvanes 26 and 27. As in the arrangement of Fig. 1, each cavity resonator system oscillates independently. Because of. the energy distribution pattern, the oscillating field energy of resonators 25 do not excite the other cavity resonator systems, and vice-versa. The same is true of the systems defined byvanes 26 and 27. The entire arrangement, as in the embodiment of Fig. 1, can be thought of as a bridge circuit, however, here there is a multiple bridge circuit consisting of three separate systems. each including four cavity resonator units, and each system being mutually decoupled from the other system.

Figs. 9 and 10 illustrate a practical. embodiment of the magnetron shown in Fig. 8. For the. sake of simplicity of illustration, the cathode is not shown in these figures. Here, vanes of like phase of one of the systems are connected together by magnetronstraps 28 and- 29-. Thus, the outer strap connects together vanes 25 and 25 and the inner strap connects together vanes 25: and 25 Naturally it would be of advantage also to strap the vanes of like phase of the remaining cavity resonator systems together. This would require a total of six straps for the embodiment illustrated in Figs. 9 and 10. In apreferred embodiment, magnetron system 25 would be loaded and the output of'the magnetron would be obtained by connecting a pair. of conductors to the two. straps respectively, as in the embodiment illustrated in Fig. 3. It is also possible to use various loop arrangements in order to extract energy from. the magnetron such as illustrated in Fig. 1. Moreover, if desired, it ispossible to drive one or more of the unloaded cavity resonator systems from an external source or sources.

similarly to the embodiment of Fig. 1. This last arrangement is particularly advantageous in cases whereit is desired to heterodyne different frequencies together and to derive an output frequency which is a result of the two. For example, it is possible to supply two separate high frequency oscillations to. the. two unloaded cavity resonator systems. It is also possible to use an arrangement such as shown in Figs. 9 and 10 as a cascade'amplifier similar tothe well known-three cavity klystron.

Although not illustrated, a three system' cavity resonator magnetron arrangement may also be produced by offsetting from one another the respective vanes of. the three systems similar to the embodiment illustrated in Figs. 5-7. Another type of mutually decoupled three:

system cavity magnetron. may be. constructed by maintaining the vanes defining eachcavity resonator system at dilferent direct potentials similar to the; embodiment illustrated. in Figs. 3 and. 4. Finally, it is to.-be under stood that any two or more of the above means for providing mutually decoupled cavity resonator magnetrons may be employed.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of magnetrons ditfering from the types described above.

While the invention has been illustrated and described as embodied in vane type magnetrons, it is not intended to be limited to the details shown, since various modifications and structural changes may be made Without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, there-fore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. A magnetron comprising, in combination, a cathode; a plurality of cavity resonators symmetrically disposed about said cathode and each having an open end facing the same, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupled to at least some of said cavity resonators for causing immediately succeeding groups, each consisting of x adjacent resonators, to oscillate together as succeeding first units forming together a first cavity resonator system, and for causing immediately succeeding different groups, each consisting of x adjacent different ones of said cavity resonators than comprise any of said first units, to oscillate together as succeeding second units forming together a second cavity resonator system, whereby said first and second units overlap one another and are mutually electrically decoupled from one another; output means coupled to one of said first units for extracting radio frequency energy from said magnetron and thereby loading said first cavity resonator system; and input means coupled to one of said second units for injecting a control oscillation into said second cavity resonator system.

2. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one, a first set of alternate ones of said vanes being conductively connected to said anode cylinder, and the remaining ones of said vanes being insulated from said anode cylinder; and means coupled to said remaining ones of said vanes for maintaining them at a direct potential which is dilferent from that of said first set of alternate ones of said vanes, whereby said first set of vanes define a first cavity resonator system and said second set of vanes define a second cavity resonator system, the units of each cavity resonator system overlapping one another and being mutually decoupled from one another.

3. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one, a first set of alternate ones of said vanes being conductively connected to said anode cylinder, and the remaining ones of said vanes being insulated from said anode cylinder; means coupled to said remaining ones of said vanes for maintaining them at a direct potential which is different from that of said first set of alternate ones of said vanes, whereby said first set of vanes define a first cavity resonator system and said second set of vanes define a second cavity resonator system, the units of each cavity resonator system overlapping one another and being mutually decoupled from one another; and output means electrically coupled to one of said cavity resonator systems for extracting high frequency energy therefrom and thereby loading said cavity resonator system, whereby said second cavity resonator system has a Q which is substantially larger than the Q of said first cavity resonator system and said second cavity resonator system thereby has a frequency stabilization effect on said first cavity resonator system.

4. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one, a first set of alternate ones of said vanes being conductively connected to said anode cylinder, and the remaining ones of said vanes being insulated from said anode cylinder; means coupled to said remaining ones of said vanes for maintaining them at a direct potential which is different from that of said first'set of alternate ones of said vanes, whereby said first set of vanes define a first cavity resonator system and said second set of vanes define a second cavity resonator system, the units of each cavity resonator system overlapping one another and being mutually decoupled from one another; and output means coupled to said first cavity resonator system for extracting radio frequency energy from said magnetron and thereby loading said first cavity resonator system; and input means coupled to said second cavity resonator system for injecting a control oscillation into said second cavity resonator system.

5. A magnetron as set forth inclaim 4, and further including means coupled to at least one of said cavity resonator systems for tuning the same.

6. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from' said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of two, each of said vanes being conductively connected to said anode cylinder, and the ends of a first set of alternate ones of said vanes connected to said anode cylinder being displaced in the axial direction of said anode cylinder from the ends connected to said anode cylinder of the remaining of said vanes, whereby said first set of alternate ones of said vanes define a first cavity resonator system and the remaining ones of said vanes define a second cavity resonator system.

7. A magnetron comprising in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavityresonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of two, each of said vanes being conductively connected to said anode cylinder, the ends of a first set of alternate ones of said vanes connected to said anode cylin- 9 der being displaced in the axial direction of said anode cylinder from the ends connected to said anode cylinder of the remaining of said vanes, and the inner ends of allof said vanes lying in an imaginary narrow cylindrical surface, whereby said first set of alternate ones of said vanesdefine a first cavity resonator system and the remaining ones of said vanes define a second cavity resonator system.

8. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the

, number of cavity resonators being equal to an integral multiple of two, each of said vanes being conductively connected to said anode cylinder, the ends of a first set of alternate ones of said-vanes connected to said anode cylinder beingjdisplaced in the axial direction of said anode'cylinder'from the ends connected to said anode cylinder of the remaining of said vanes, and the inner ends of all of said vanes lying in an imaginary narrow cylindrical'surface, whereby said first set of alternate ones of said vanes define a first cavity resonator system and the remaining ones of said vanes define a second cavity resonator system; and means coupled to said first cavity resonator system for extracting radio frequency energy from said magnetron and thereby loading said first cavity resonator system, whereby said second cavity resonatorsystem' has a Q which is substantially larger than the Q of the first cavity resonator system andthe second cavity resonator system thereby has a frequency stabilization efiect on said first cavity resonator system.

9. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of two, each of said vanes being conductively connected to said anode cylinder, the ends of a first set of alternate'ones of said vanes connected to said anode cylinder being displaced in the axial direction of said anode cylinder from the ends connected to said anode cylinder of the remaining ofsaid vanes, whereby said first set of alternate ones of said vanes define a first cavity resonator system and the remaining ones of said vanes define a second cavity resonator system; and means coupled to each of said cavity resonator systems for tuning said cavity resonator systems.

10. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anodecylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open endfacing said cathode, the number or" I cavity resonators being equal to an integral multiple of two, each of said vanes being conductively connected to said anode cylinder, the ends of a first set of alternate ones of said vanes connected to said anode cylinder being displaced in the axial direction of said anode cylinder from the ends connected to said anode cylinder of the remaining of said vanes, whereby said first set of alternate ones of said vanes define a first cavity resonator system and the remaining ones of said vanes define a second cavity resonator system; a pair of tuning rings located inside of said anode cylinder and concentric with said cathode, one of said rings being arranged adjacent said first cavity resonator system and the other of said rings being arranged adjacent said second cavity resonator system; and mechanical means independently coupled to each ot'said rings for permitting movement thereof toward and away from the respective cavity resonator systems.

11. A.magnetron comprising, in combination, a cathode; a plurality of cavity resonators symmetrically disposed about said cathode and each having an open end facing the same, the number of cavity resonators being equal to an integral multiple of x, at being an integer greater'than one; and means coupled to at least some of said cavity resonators for causing immediately succeeding groups, each consisting of 2: adjacent resonators, to oscillate together as succeeding first units forming together a first. cavity resonator system, and for causing immediately succeeding different groups, each consisting of x adjacent difierent ones of said cavity resonators than comprise any of said first units, to oscillate together as succeeding second units forming together a second cavity resonator system, whereby said first and second units overlap one another and are mutually electrically decoupled from one another, each of said first units being defined by a pair ofexterior Wall portions having ends close to said cathode, said means comprising a first strap connecting said ends of said wall portions of a given phase together and a second strap connecting the ends-of said wall portions having a phase opposite that of said given phase together.

12. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end'facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; and means coupled to at least some of said cavity resonators for causing immediately succeeding groups, each consisting of x adjacent resonators, to oscillate together as succeeding first units forming together a first cavity resonator system, and for causing immediately succeeding different groups, each consisting of x adjacent difierent ones of said cavity resonators than comprise any of said first units, to oscillate together as succeeding second units forming together a second cavity resonator system, whereby said first and second units overlap one another and are mutually electrically decoupled from one another, said means comprising a first strap connecting together the inner ends of the vanes of a given phase of said first cavity resonator system, and a second strap connecting together the inner ends of the vanes having a phase opposite that of said given phase of said first cavity resonator system.

13. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupled to at least some of said cavity resonators for causing immediately succeeding groups, each consisting of x adjacent resonators, to oscillate together as succeeding first units forming together a first cavity resonator system, and for causing immediately succeeding different groups, each consisting of adjacent different ones of said cavity resonators than comprise any of said first units, to oscillate together as succeeding second units forming together a second cavity resonator system, whereby said first and second units overlap one another and are mutually electrically decoupled from one another, said means comprising a first strap connecting together the inner ends of the vanes of a given phase of said first cavity resonator system, and a second strap connecting together the inner ends of the vanes having a phase opposite that of said given phase of said first cavity resonator system; and output means for extracting radio frequency energy from said first cavity resonator system comprising a coaxial line extending into said magnetron, the center conductor of said line being connected to one of said straps and the outer conductor of said line being connected to another of said straps.

14. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupled to at least some of said cavity resonators for causing immediately succeeding groups, each consisting of x adjacent resonators, to oscillate together as succeeding first units forming together a first cavity resonator system, and for causing immediately succeeding different groups, each consisting of x adjacent different ones of said cavity resonators than comprise any of said first units, to oscillate together as succeeding second units forming together a second cavity resonator system, whereby said first and second units overlap one another and are mutually electrically decoupled from one another, said means comprising a first strap connecting together the inner ends of the vanes of a given phase of said first cavity resonator system, and a second strap connecting together the inner ends of the vanes having a phase opposite that of said given phase of said first cavity resonator system; output means for extracting radio frequency energ from said first cavity resonator system comprising a coaxial line extending into said magnetron, the center conductor of said line being connected to one of said straps and the outer conductor of said line being connected to another of said straps; and input means coupled to said second cavity resonator system for supplying a control oscillation thereto.

15. A magnetron as set forth inclaim 14 wherein the walls defining the cavity resonators comprising said second cavity resonator system are formed with a silver plating thereon, whereby the Q of said second cavity resonator system is substantially increased.

16. A magnetron comprising, in combination, a cathode; a plurality of cavity resonators symmetrically disposed about said cathode and each having an open end facing the same,'the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupled to at least some of said cavity resonators for causing immediately succeeding groups, each consisting of x adjacent resonators, to oscillate together as succeeding first units forming together a first cavity resonator system, and for causing immediately succeeding different groups, each consisting of x adjacent different ones of said cavity resonators than comprise any of said first units, to oscillate together as succeeding second units forming together a second cavity resonator system, whereby said first and second units overlap one another and are mutually electrically decoupled from one another; output means coupled to one of said first units for extracting radio frequency energy from said magnetron and thereby leading said first cavity resonator system, whereby said second cavity resonator system has a Q which is substantially larger than the Q of said first cavity resonator system and said second cavity resonator thereby has a frequency stabilization efiect on said first cavity resonator system; a layer of silver coating the walls of the cavity resonator systems, whereby the Q of said second cavity resonator system is substantially increased; and tuning means electrically coupled to said second cavity resonator system for tuning the same.

17. A magnetron comprising, in combination, a cath- 12 ode; a plurality of cavity resonators symmetrically disposed about said cathode and each having an open end facing the same, the number of said cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupling together an integral number of groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form a first cavity resonator system composed of said groups; and means coupling together an equal number of other groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form at least one other cavity resonator system composed of said other groups, each of said groups of one of said systems having at least one of said cavity resonators in common with one of the groups of another system, said different cavity resonator systems being arranged in a cyclically overlapping consecutive relationship and being electrically decoupled from one another.

18. A magnetron comprising, in combination, a cathode; an anode cylinder symmetrically disposed about said cathode; a plurality of vanes symmetrically arranged about said cathode and extending inwardly from said anode cylinder toward said cathode, said vanes defining a plurality of cavity resonators, each of said cavity resonators having an open end facing said cathode, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupling together an integral number of groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form a first cavity resonator system composed of said groups; and means coupling together an equal number of other groups of x consecutively adjacent cavity resonators out of said plurality thereof. so as to form at least one other cavity resonator system composed of said other groups, each of said groups of one of said systems having at least one of said cavity resonators in common with one of the groups of another system, said different cavity resonator systems being arranged in a cyclically overlapping consecutive relationship and being electrically decoupled from one another.

19. A magnetron comprising, in combination, a cathode; a plurality of cavity resonators symmetrically disposed about said cathode and each having an open end facing the same, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupling together an integral number of groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form a first cavity resonator system composed of said groups; and means coupling together an equal number of other groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form at least one other cavity resonator system composed of said other groups, each of said groups of one of said systems having at least one of said cavity resonators in common with one of the groups of another system, said different cavity resonator systems being arranged in a cyclically overlapping consecutive relationship and being electrically decoupled from one another; and output means coupled to one of said first groups for extracting radio frequency energy from said magnetron and thereby loading said first cavity resonator system, whereby said second cavity resonator system has a Q which is substantially larger than the Q of said first cavity resonator system and said second cavity resonator system thereby has a frequency stabilization effect on said first cavity resonator system.

20. A magnetron comprising, in combination, a cathode; a plurality of cavity resonators symmetrically disposed about said cathode and having each an open end facing the same, the number of cavity resonators being equal to an integral multiple of x, x being an integer greater than one; means coupling together an integral number of groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form a first cavity resonator system composed of said groups;

and means coupling together an integral number of pling together an equal number of other groups of x consecutively adjacent cavity resonators out of said plurality thereof so as to form at least one other cavity resonator system composed of said other groups, each of said groups of one of said systems having at least one of said cavity resonators in common with one of the groups of another system, said different cavity resonator systems being arranged in a cyclically overlapping consecutive relationship and being electrically decoupled from one another; output means coupled to one of said first groups for extracting radio frequency energy from said magnetron and thereby loading said first cavity resonator system, whereby said second cavity resonator system has a Q which is substantially larger than the Q of said first cavity resonator system and said second cavity resonator system thereby has a frequency stabilization effect on said first cavity resonator system; and a layer of silver coating the walls of the cavity resonator systems, whereby the Q of said second cavity resonator system is substantially increased.

References Cited in the file of this patent UNITED STATES PATENTS 2,343,487 Steudel Mar. 7, 1944 2,474,898 Heising M July 5, 1949 2,485,401 McArthur Oct. 18, 1949 2,635,209Clogston Apr 14, 1953 2,766,403 Skowron Oct. 9, 1956

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