US2476971A - Electron discharge apparatus of the velocity modulation type - Google Patents

Description

y 1949- J. H. FREMLIN ET AL 2,476,971

ELECTRON DISCHARGE APPARATUS OF THE VELOCITY MODULATION TYPE Filed Feb. 19, 1943 ITTTHIHIILUUI I nvergtors Atiomei! JbhL lizayer F-euzljzu I Patented July 26, 1949 UNITED STATES FATE!!! T F VELOCITY MODULATIQNQyrE John Heaver Fremlin and Christopher Hem'y Foulkes, London, England, assjgpprs, zby; assignments, torlnternational standard:

Corporation, New -York, Nrx a caper {Delaware Application February 19, 1943, Serial*No. 476;46 In Great Britain February-19, $1952 23 Claims. (01. 25 1 27 5) The present invention-relates-to electron discharge apparatus. of the velocity modulationitype and has for its object to provide an improved construction :of ultra high frequency oscillator or-other tube adapted-t0 work, vfor example, at a wavelength aroundthree centimeters and comprising an improved arrangement by which power may be takenvtherefrom.

..According to the invention an electron .discharge device of :the -velocity :mo'dulation ctype comprises a cavity resonator system having a plurality ofresonant cavitiesand a conducting path coupling at'least two of isaidresonant cavities .and an antenna mounted within vthe .enyelope of said device and in electricalcontact with said path so as to berexcited by said system.

The electron discharge .device, as 'will beepparent to those'skilledointhe-art may be .of. the simple-cavity resonator reflected beam type. or. of the type having twor or .more cavity resonators with a beamsniferingv reflection :orv not. Theantenna may alsoucomprise a single rod antenna. .or a dipole antennaoranyother shape which. pro- .duces 1 the type of electromagnetic wave :it ,is desired. to set' up and transmit.

, Theelectronrdischarge apparatus according to the invention is. particularly adapted for use with waveeguides or with .other:cavity.resonators to which the output from .t'hBfBlGCtIOII discharge device may-be fed,, for exa-inple to amixing, cavity device as the superheterodyning frequency for, receiving ultraghigh frequency wavesto give an intermediate frequency.

In the .case of -,a;ro.d;antenna wherethe-lantenna is -excited,by direct. electrical'contact with the resonatorsystemthe connection is madein the vicinityota voltageiantie-nodal point of the system,/and in zthe:case=of ,a dipole, one of-;;the connections; of the i dipole ,.is "made at or in the vicinity;of::a1voltage:antifnodal point of thesystem and the other. connection 1 to the -=di,p01e ,is made rat :or: in; the w'vicinity of ;a voltage antinodal :point in: opposite phase to the first-point. JIhese ,points;0f ;.ccnnection:arev ad'jnstahle; so as to match or" adjust: theoutput, impedance of; the system to the antenna-impedance.

The invention -;wi1l be better understood from the following descriptionxtaken-in conjunction with the; accompanying .drawingsrwhich showl by way of. e am le:oneiembodimen 0f he invention.

;In thedrawinssfiigl; is a plan View of. the "interior; ofrthe; apparatus; Figs; 2 land, 3;;are side yiews;:1ooking;;in :fthe: directions 10f; the. arrows- A Land-B respectively z-iIfFiE.i;1;;bt1t;0f the complete which weldedetc the ,gtoneofi p at anda1s0. t0

the end,ofthe -rcduantenna.

' Th tackzof -.D1ates; eandivendmembem sando betweenathem a m ga-nlatefl 3;ofganoo1a iormationaa shqwni inz Eieur 'aaaand-i lamin tion of:six-18111 1.-i ilriemelons thanpthe Qther ,-lan1iv ff high frequency power of a serious nature may is of such diameter as to contact with a, metallic portion of the envelope referred to later, and a lower portion of the same 'oute'rdimensions as chamber structure I. The plate IShas a cen-' tral aperture l6 as shown in -Figs'. 2 and 3 to allow the antenna l2 to pass freely' therethrough;. 'lhe upper surface of the plate l-' z n'aybe' dished or-of;

other form to function as a reflector for-theelectromagnetic waves emitted by the antenna.

The plates of the chamberstructurel together with the plates I3, l4 and I5 are heldrtogether by bolts I8 (Fig. 1) formed on the plate l5v or otherwise provided and by nuts l9 screwed on the'ends of the bolts. The whole structure is mounted on the base of a U-shap'ed member through which pass two of the bolts l8. This member i1 is then securedto two supporting pillars secured in the press oi the envelope. A lead-in wire is connected to one-of'these supportin pillars and to a pinin the base, so that'a potential may be applied tothe resonator structure. The electrodes-; 6', and 8' have also lead-in wires connected to respective pins in the base in a manner usual in electron discharge devices. The cathode 1 heater pins has no connection. 7

The envelope of the apparatus comprises a main'body portion 20, provided with the press and securedin'th base in well knownmanner.

nae the other end-of this body portion is sealed a -tubiiIar-inetaIlic piece -2|.; This part 2| has ajportion ofreduced diameter asshown and the envelope is closed by aglass cap 23 which may be oflead' glas's for' ease ofseialing-sealed to the upperedge of the part -2|.--When assembled t e plate l5' 'makes" direct electrical'contact with the interio'r'surface of the part 2| anda suitably apertured plate '22 is fixed inelectrical contact with the outer-surface of the part 2|; The disc 22 is soldered to the-part 2| after the valve is pumped andthe space between 2| and 22 may be fllled with a low melting point solder. The part 2 [and the member 22 may comprise a sinle 'apertureddisc sealed into the wall of the tube and concentric therewith, the plate 5 then making electrical contact with the part of the disc projecting into the'interior ofthe envelope.

'In use, theend or a wave guide or of a cavity resonato'r-orother similar device to-which it is desired-to feed the ultra high frequency electromagnetic waves, is placed over the end of the envelope to make electrical contactwith the plate 22 which may be provided with apertures or other suitable means for securing the wave guide or resonator thereto.

-Whi1e a rod antenna has been shown in the drawings, it will be understood as already pointed out hereinbefore that other 'forms' of antenna may b'e'used 'depending'upon the type of wave it is desired to transmit. Furthermore other constructions of resonant chamber systems and other velocity modulation devices may be used in carrying out the invention. Furthermore, other suitable supporting means may be provided for the antenna, but'any mica parts used must be 7 arranged as in the abovedescribed example so While the embodiment given by way of example has been describedas an oscillator, it will be 'understood'that the electron discharge apparatus according to the invention may take on other functions, for example as an amplifier.

. What is claimed is:

. .An electron discharge device of the velocity modulation type comprising a plurality of cavity resonators, conducting means forming a common external wall for at least two of said cavity resonators and providing an electrical conducting path externally of the cavities of said resonators and coupling said two resonators together, and an antenna external to said cavity resonators and mounted' directly on said conducting means at a point in said external conducting path so as to be excited by said system. 7 V

2. An electron discharge tube of the velocity modulation type comprising an evacuated envelope, a cavity resonator system' in the form of a block built up of a series of apertured plates forming a plurality of. cavity' resonators, conducting means forming a'commonexternal wall be excited by the electric waves on said conduct- 7 ing means, said antenna being enclosed within said evacuated envelope;

I 3."An electron discharge device of the-velocity modulation typelcomprising' a cavity resonator system 'havingaplurality of tubular cavity resonatorsgconducting means forming a common external wall for atleast two of said cavity resonators and providing an electrical conducting path coupling said two resonators together, 'a plate mounted on-the end of said: system and having an aperture therein, an antenna external to said resonators passing through said aperture and mounted directly on said conducting means so as to be excited by the electric waves occurring 'on said plate, and an apertured' member carried by the envelope of said device and electrically connected with said plate. 'i.

4. An electron discharge d'eviceiof the velocity modulation type comprising a cylindrical 'ev'a'cu ated envelope, a cavity resonator system having a plurality of cavity resonators o'fcylindric'al form mounted within said envelope with'tl'ieir axes parallel to the axis of said envelope; conducting means forming a common external wallfor at least two of said cavity resonator-s and providing an electrical conducting path'superfic'ial'to said system coupling said' two resonators together, and an antenna external to said cavity resonators and mounted within" the envelope of said device and directly on said'conducting'm'ea'ns so as to be excited by the electrical waves occurring on said'conducting means,

5. An electron discharge device of the'veloeity modulation typecomprising an' evacuated enity resonators of uniformtransverse' sections along the respective linear longitudinal, axes, said axes being parallel to' each Iother each having alo'ngitudinal aperture in the wall thereof 7 parallel to the respective longitudinal aperture in the wall thereoFpa'r'allel to the respective n tudinal of said resonators means for Pie-deems b am o trons o Substantially rectangular transverse section and for directing said beam past said apertures in turn, a conduct: ing plate arranged transversely with respect to said resonators forming an external end wall f"?! aid resonators and providing an electrical '3n it ne ath, sa d envelope, coupl n said eseaete s a d an an nn external to an r qneter a d haunt d e on Said plate so as to be eigcited bythe electric waves occurring on said plate.

6. An electron discharge tube according to claim 2 further comprisilli a metallic member sealed into the wall of the evacuated envelope making electrical contact with the block, where-. by the, tube may be conveniently mounted in a transmission system and the block may be er a.

7;. electron discharge. device according to claim said antenna comprising a conducting eel w h s longitudina axis parallel with the i t sa d envelope.

8, in electron discharge device according to s a urther mpr s nga metallic member seal d into, the wall of; the evacuated envelope, and means making electr cal contact between said member and said resonator system, whereby the device may lee-conveniently coupled to radit i91 8 5 dev ce the resonator system may be earthed.

9. An electron discharge, device according to l i 5 fur h r pa as te a metallic n ith sealed into the wall 8f the evacuated envelope; and ns ra s l e iect t sel between said member-and the walls ofisald cavity resonators whereby the device, be conveniently ee te ra ate lei9.. e. 9at de and sa arthed ardin t ith thegreater seeiie arall to e l te inel te 4 'e rb. discha ge ev e e na m d ie il t ne QIF l cavity system havinga plural y; of cavity resonators built u from a staclg oi} like apertured conducting plates and coupled together by means of the conducting path provided by an end plate, means for producing a beam of electrons and for directing said beam with its greater transverse dimension parallel to the depth of said stack, slots in said conducting plates for coupling the resonators of said system to the electron beam, and an antenna external to said stack and mounted directly on said end plate so as to be excited by the electrical waves occurring on said path.

12. An electron discharge device according to claim 11 further comprising a metallic annular member sealed into the wall of the evacuated envelope, means making electrical contact between said member and said stack of like apertured conducting plates, said means comprising a conducting plate having an aperture through which said antenna passes, whereby the device may be conveniently coupled to radiate into a load device and said stack may be earthed.

13. .An electron discharge device of the velocity modulation type, comprising a. resonating cavity system having cavities of uniform cross sections along their respective linear longitudinal axes and gaps connecting said cavities with a beam gap, said system comprising a stack of thin metal stampings having apertures therein s a ed, to rr spo o th desired ross see tim of t e on n a ie and s ots correspend g to th a s and t e end. plate los one nd of e e n n avities forme by the 5 apertures in said stampings, a source of electrons, means for forming the electrons into a beam, means for directing said beam along said beam gap, and an antenna external to said stack m un ed n the e p ate and. in conta t the ewith so as to be excited by the ultra high requene Waves oc u r n n. said. pl te.

14, An electron discharge device accordingto claim 13 further comprising an annular metallic member sealed into the wall of; the evacuated en velope, means making electrical contact between aid mem e nd id s ac o metal stampnss er b t e dev c may be. conveniently equ led to d at in o a load ev and said stack may be earthed.

1 An e e o harg e i e, of; hevelocity mod l y e c mpr si a plura i y ofl k conducting plates, each having a plurality ofapertures in alignment and slots connecting said apertures to the edges of said plates, said plates beingso stacked one upon another that the cor-, responding apertures of said plates are in align! ment forming cavity resonators and the corre- RQ -min slots a n ali nment d a ondu ti-ng end plate closing one end of at least two of said cavity resonators, a' source o a beam of ectr n i e n to said. stacke plates, means mount adjacen tov beam. ath f r directin said beam past the slots; of a plate in succession th h on er dime i n i the r nsv se sec he o he beam; 12 1 9 he depth or. the a xternal o a d cavity a c. ion andi n eo tactwith he nd letecfhe-staple se -fa med so are ex el y e e s wavesieec irr ns-on saidend:

Anleetrqn, discharge device according; to claim, ,5 pr s ng; ur her condu tin plates preferably of high heat resistance having like apertures to those in the first mentioned plates but no slots, said further plates being interleaved between said first mentioned plates in the stack with their apertures inv alignment with the aper-- tures 'insaid first mentioned plates, said further plates forming a grid on the beam path.

17. An electron discharge device according to claim 15 further comprising an anular metallic member sealed into the wall of the evacuated envelope, means making electrical contact between the stack of conducting plates and said member, whereby the device may be conveniently coupled to radiate into a load device and said stack may be earthed.

18. An electron discharge device of the velocity modulation type comprising a plurality of like conducting plates each having a plurality of apertures in alignment and slots connecting said apertures to the edges of said plates, half the number of said plates being stacked one upon another so that corresponding apertures of said plates are in alignment forming a cavity resonator and the corresponding slots are in alignment, the other half of the plurality of plates being formed into a like stack forming a cavity resonator, means retaining the two stacks in fixed relative positions with corresponding slots directly opposite each other and with a space to form a beam gap between said stacks, a conducting end plate closing one end of each said resonator, a source of a beam of electrons adjacent to said stacked plates, means arranged adjacent to'thebeam path for directing said beam along said beam gap with its greater transverse dimension parallel tothe depth of the stack, and an antenna, external "to said cavity resonators and mounted in contact with the said end plate so as to be excited by theelectrid waves occurring on said end plate. 7'

19. An electron discharge device accordingto claim 18 comprising further conducting platesfof high heat resistance having like apertures to those in the'first mentioned conducting plates but no slots and located relatively to each other asare the apertures in the two assembled stacks, and slots connecting the apertures'of 'a'p'air'in said further conducting plates correspondin'g'to a pair of apertures on either side of said beam gap and immediately opposite each other, said further plates being interleaved between the conducting plates of the said two stacks with their apertures in alignment with corresponding apertures in said stacks and forming a grid across the beam gap. 7 20.An electron discharge device accordingto claim 18 further comprising an annular metallic member sealed into the wall of the evacuated envelope, meansmaki'ng electrical contact between the two stacks of conducting plates and said member, whereby the device may-be conveniently coupled to radiate into a load device and said stacks maybe earthed. 7 21. An electron discharge device of the velocity modulation type, comprising two'stacks of like apertured conducting plates positioned to leave a beam gap therebetween for the passage of an electron beam, the apertures in said plates forming'cavities of uniform cross section'along' the depths of the stacks and longitudinal slots consta'clz,'and anantenna mounted on and, in contact with'the end'pl'ate of at least one stack so asto be excited. by the electric, waves occurring on said endplate." r V '22; An ultra; highfrequency electron discharge device according to claim 21 further comprising thicker plates at l the' top and bottom of the stack of plates and like apertured to said further conducting plates to define the greater depth of the beain gap, and a further thicker plate at the antennaend having an aperture, said an tenna. passing through said aperture'so as tobe insulated from said further thicker plater ,23. An electron discharge device according to claim '21 further comprising an-annular metallic member sealedinto-the wall ofthe evacuated envelope: an internal conducting 'plate mounted on the antenna end of said stack, making electrical contact between said stack and 'saidannular member, an aperturein saidint'ern al con- 1 ducting plate through which the said antenna passes,- and'a conducting plate external to the evacuated envelope and having an; aperture therein; the periphery of said aperture making electrical contact with said annular metallic member, whereby the device fmay be conven iently coupled to radiate into'a loa'd device and said'st'acksmay be earth'ed, l" m l r J OHNHEAVER FRENILIN. v I

' CHRISTOPHERHENR REFERENCES CITED} w v effiol lorwingbreierenlces areiof record inithe file of this patent;

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