US2637003A

US2637003A -

Info

Publication number: US2637003A
Authority: US
Publication date: 1953-04-28
Anticipated expiration: 1970-04-28

Description

produce fumi impedsncediscontinuit! therein conductor of a super-high frequency transmission system. is shielded from abrupt physical mision intofthe dielectric Propagation mediam therein. and therefore ,from close enough parallel coupling to any electromagnetic nelds whichmaybemscatthereintcauenubltam tiaidissontinuityintheimpedanceofthssystem althepotnt whcrethediodeisbuiltin feature of the invention is anzsrmgellislitofthe built-indiodewithavery short inta-sm spacing to aiford two simultsneous advantages: (l) thatthcdiodewill to produce relatively large noiseeurrentsnvarawideband of frecuencias. and (2) thatthe electron stream will not be abierto absorewh energy from any electromy exist within the holoondilctor..ise., that the electron stream l,egnllierltothateiiergyandtherefore will notsubstantially alter the impedance ofthe systemat the point where the diode is .'Amnsl'tinbrhamcftheinventionis an arrangement wherebythe shunt impedance pressndtothediodebythesectionoithem- Atcwlnichrist-is builthasasuitably high valise for mi useful amounts of noise power. Molte anrllsmc reduction of an intermi dimensii of the hollow conductor of that sectim to preside a short discharge space for thediodawhiislatthesametimetheshunt impedaneewhichthediodepresentstothesystem isreiativelyhighduetoits opationwith tembiecinwillbeapparent from the folof the invention pointed out withparticulariuhtheappendedclaimsand taken in connection with the accompanying PigJisasiderinlofanoisediodeconstructed in accordance with-s preferred embodiment of the invention, thadiode being incorporated into asectionofwaveguide portionsofwhichare Msanseaienspecuvnyampviewmd aant-awayldevlewofaporticnofthestruc- Pigs. s and@ represent a modification ofthe taken aiong'iine I-l armures. andlllgures being aleftendviewofmure.

Similar reference characters are applied to similar elements throughout the drawings.

Referring to Fig. l, the diode comprises a wave guide section l0 which in the present embodiment is o! the rectangular type and preferably is of some standard size and which also functions aa part of the tube envelope. Section Il carries at its opposite ends flanges il and l! by which it may be readily connected into a standard waveguide transmission system. The flange Il and if may include R. F. (radio frequency) chokes or any other desirable known features for assisting coupling. In the diode ahowninFig.1aportion iloftheinnerwnll of the top of waveguide section It acts as the anode. Since ordinarily the metallic tubes coilprising a waveguide system are grounded. the energizing potential for this diode will preferably be applied as a negative potential to its cathode (filament Il). .Howeven if desired, the entire section Il may be D. C. insulated from the rest of the waveguide system so that it will be possible to apply the energizing potential to it as a positive potential. In either case the ma tion I! of the inner wall of the section will lis at a higher potential than the diode-cathode.-`

l'br efficient operation it is essential that the inter-electrode space for this diode be vos! short. If the transit time from the cathode to theanodcisgraduallyincreaseditwillbenoted that when it is equal to about one-half of period corresponding to the center frequency of the operating band, or, to be more exact. when it is equal to 3-5 radians at that frequency. the noise current will be down very markedly. more particularly the mean squared noise current i?) willbedownbyo. andwillbedecreasingata rapid rate. The mean noise current may be considered as an integration of random curreit impulses each of which ls produced during the transit of an individual electron from the cathode to the anode. According to Fourier. if the transit times are very short the current im pulses will include many high frequency com,

ponente having significant magnitudes whereas L iftheyarelongthiswillnotbetrue. This, when the noise current drops because of in creasesintransittimethelossismostlyinim high frequency components. Accordingly it is desirable for the diode to have a short transit time. Moreover. it is desirable for the transit time to be short for mother reason, this being that its duration aifects the A. C. plate resistance ofthediodeinsuchamannerthatevenifit is operated with temperature-limited emission ,it can seriously load the guide if the transit timefb too long. But this of itself does not mean that the interelectrode space must be short. since it is possible to decrease the transmit time by i ncreasing the electron velocity. i. e.. by using larger and larger potential gradients between the cathode and the anode. However. if the dis-` charge space is over the full distance from the bottom to the top of a standard waveguide, the potential necessary for a transit time of less than 3.5 radians is so great ss to be impractical and uneconomical.

Accordingly the present arrangement provid. for a very small interelectrode discharge space. Moreover. it provides the small discharge space without entailing any protrusion of the cathode into the dielectric transmission medium in the LFisures beingasection 1g section. v'Iothisenrithe cathode,whichinthe T... tu mm muwmmmmmmmmm a mmmmm .mm.m..mmmmmmm mmmmmmmmwmmmm @www u o :u r u n w m mamut m m y .mm mm.. Mtn f.. mm www www@ mmwmmmmmmwmmwmmm mmmmdmmm mmmwmmmmmmmm www MmmmmwmmmwmmmmmmwmmmmmmmmMmmmmmmmmwmmmmmm mmmm wwmwmb wwwmwmmmwwmmwmm-mww.mmmmmmmmmmwmmmmmmww am? mim wmmmmm E@ mtmm.@wmmmmmww w.. u mn .m t en hE w m mummfmn.. mdwm.. mmd u mw .m @mm m mmmmmmwmmmmmmwmmmmmmmmmmmMmmmMmmm@wwwMmmmmmmmmmm my mmm m mmmmmwwm mmmm man m u w Mwm" magma mm mmm ..mmm m m m mmm mmm w. mm n?. am m m .am m m mm L?? w w m m m mmmmmmmmmmm mmmmmmmmmmmmmwm mm www L m mas m. my mmm mwmm-, Mmmm mmummmmwnm mmm mmmmmmmmwnmmx .um n wmmmm mmm mnwwLmemmmmmmmdmmm muffa. Mmmm .www mnmmmwmtmm ...Mmmmmmmmmwmwmmnmm mmmwmmm mmmwymm www .Mmmm .hmmm wwwmmmwwmarmmmxm n. m. am www@ s mrww mmm mm mm .mmmmmmmmmvmmf n.mmmmm Mmmm.; m mm u m n amm .u u m @www mm. m. fmm www mm mm mm mmwww@mmmmmmwmmmmwwmmmmmwww mmmmmmmmmmw www ...u ,w .a um... m m my 1 ...an m ....aww n m Mmmm n.. d um my@ f m Ln .a ummmlmmmmmnmnwmmmmm n MNM output ends according to principles known to the waveguide art. If it should be desired to utilise the diode in the same frequency range as that over which the embodiment of Fig. 1 is use- IuLalIthatisnecessaryistoaddtotheends of the section Ila two sections of waveguide which contain the long. tapered end portions so that. when the three sections are connected together. the result will be the electrical equivalent of the diode of Fig. l. Obviously it is desirable that the break between auch attachable tapered endportionsandthebluntendstlbeassmallas possible. Forthisreasonthinvacuumsealasuch as mica windows, are to be preferred for embodiments of this type. On the other hand. if it shouldbedesiredtooperatethediodeoveran extended band of frequencies or over a band of frequencies not entirely within the operating band of an embodiment of the Fig. i type. diiferent types of attaohable sections should be connectedtotheendsofthediodesuchasimpedance transformers containing appropriately tapered for the ridge 88, or other transformlna devices known to fthe art.

Although our improved diode has been desorihedineonnectionwithitsuseasanoisediode forthepm'poseofmakingcertaintestsandmeasurements. it is evident that a device of this type may have various other applications wherever it is desirable to maintain a certain circuit impedanceandhaveattbesame timeanelectron discharge device in this circuit without disturbing the .characteristics thereof. It willalsobeevidentthatinsteadofbeinglimited to a two-element tube. other elements may be incorporated in our tube. Therefore, while we have indicated the preferred embodiments of our invention of which we are now aware and have also indicated enh certain specinc applications for which our invention may be employed, it will be apparent that our invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be madeintheparticularstructureusedandthe purpose for which it is employed without departing from the scope of our invention as set forth in the appended claims.

What I claim is:

l. A ridge structure for a hollow conductor which enoloses an electron discharge device wmprising a thin elongated ridge base. a ridge insert carried by the central portion of the ridge base, with nelatlvely large portions of its surface closely-juxtaposed to surfaces of said ridge base. insulating material having a high dielectric constant interposed between said juxtaposed surfaceswherebytheridgebaseandtheridgeinsertacecoupledastoltnenergybyalarge capacitancebutareisolatedastoD.C.,theridge insertoomprisingaprincipalportionandaminor insert carried by the principal portion but insulated therefrom as to D. C., an elongated cathode having its respective ends directly connected electrically tothe two portions of the ridge insert. and a recon in the ridge insert extending alongitforallofthelengthofsaidcathodeintermediate its ends whereby except for said ends saidcathodeisnotindirectelectricalcontact with any conductive portion of the ridge structure.

2. A ridge structure for a hollow conductor which encloses an electron discharge device com prisingathinelongatedridgebasehavingacentral portion of given height and tapering gradually in height from said central portion toits two extremities, a ridge insert carried, by said'central portion with relatively large portions of its surface closely-juxtaposed to surfaces thereof. insulating material having a high dielectric constant interposed between said juxtaposed surfaces whereby the ridge base and the ridge insert are coupled as to R. F. energy by a large capacitance but are isolated as to D. C., the ridge insert comprising a principal portion and a minor insert carried by the principal portion but insulated therefrom as to D. C., an elongated niament having its respective ends directly connected electrically to the two portions of the ridge insert. and a recess in the ridge insert extending along it for all of the length of the filament intermediate its said ends whereby except for said ends said lament is not in direct electrical contact with any conductive portion of the ridge structure.

3. A ridge structure for a hollow conductor which encloses an electron discharge device comprising a thin elongated ridge base, a ridge insert carried by the central portion of the ridge base with relatively large portions of its surface closely-juxtaposed to surfaces thereof, insulating material having a high dielectric constant interposed between said juxtaposed surfaces whereby the ridge base and the ridge insert are coupled as to R. l". energy by a large capacitance but are isolated as to D. C.. the ridge insert comprising a principal portion and a minor insert carried by the principal portion. a filament having its respective ends directly connected electrically to the two portions of the ridge insert. the ridge insert being formed withashallow depression along its top surface between the points of connec tion of the respective ends of the mament whereby exceptforitssaidendstheillamentisnotindirect electrical contact with any of the conductive portion of the ridge structure, and means for supporting the nlament under tension between the ends of the depression to bridge it so that as toR.F.currentsthefilamentwillactasthe top surface of the ridge'structure.

4. A ridge structure for a hollow conductor which encloses an electron discharge device comprising a thin elongated ridge base, a ridge insert carried by the central portion of the ridge base with relatively large portions of its surface closely-juxtaposed to surfaces thereof. insulating material having a high dielectric constant interposed between said juxtaposed surfaces whereby the ridge base and the ridge insert are coupled as to R.. F. energy by a large capacitance but are isolated as to D. C., the ridge insert comprising aprincipalportionandaminorinsertcarriedby the principal portion but insulated therefrom as to D. C., a filament having its respective ends directly connected electrically to the two portions of the ridge insert. the ridge insert being formed with a shallow depression along its top surface between the points of connection of the respective ends of the lament whereby except for its said ends the filament is not in direct electrical contact with any of the conductive portion of the ridge structure. means for supporting the filament under tension between the ends of the depression to bridge it so that as to R.. F. currents the filament will act as the top surface of the ridge structure, the ridge insert being formed to denne a cavity for receiving an element of said supporting means consisting of a slightly loaded spring connected to one end of the filament to keep it under tension, and a corrugated metal ribbon connected between said one end of the asszooa largeportionsofitsnnfaoaeloselyduxtaposedto surfaces thereof. imulating material having a agr' eonduetortoapointatwhichitisjoinedtnan endofsaidridge.thetaperingoftheridsebeing symmetricalinthatoneachofiendsitstopprlaoh one another from said central portion so as smoothly to join one of said inner conductors. i3. An electron discharge device comprising an conductor, a ridge connected inner wall of the hollow conan emissive surface. to support the cathode its smilve surface adjacent to a portion of the opposite inner wall of the conductor which ananodeforthe deviceandwith said econductoratleastoneoftheseals abutmgagainst ablunt end of the ridge.

l4.--An evacuatedelectrondischargedeviccincludingatubularanbdeof predeterminedcross sus o mountedwiththeemlssivesurface thereofin substantially the same plane as adjacent surfaces of the support. j

I6. An electron discharge device including a tubular conductor. electromagnetic-enersy-permeable means hermeticaliy sealing the ends of saidV conductor, a cathode within said tubular conductor, said tubular conductor serving as an anode for said cathode. an elongated support supporting said cathode closely adjacent the inside ld surface `of'suid tubular conductor, said support having an enlarged central portion supporting said cathode and tapered end portions, said tapered end portions serving as impedance transfonnerswhensaiddevlceisutilinedinanl".

n system.

id. Anelectrondischargedevicecomprisingan envelope including a section of wave guide sealed at both of its ends with electromagnetic-energypermeable material. emotion-receiving means including an elongated surface extmding along the inside of a wall of the section of wave guide and facing toward the inside of its opposite wall to serve as an anode for the discharge device, said section containing an elongated ridge having a bottom side which is physically attached to said inside of said opposite wall in such a position that a central portion of the top side of the ridge registerswithsaidelongatedsurfacetoactasa support for a cathode to cooperate with that surface, theheight of the ridge as measured between its top and bottom in its central portion being large enough so that in said central portion its top is closely juxtaposed to said elongated surface while its height in iin end portions progressively lessens until it is negligibly small at its two extremities, means providing direct current insulation and radio frequency capacitive coupling between said inside of said opposite wall and at least the central portion of the top side of the ridge. a thermionically emissive surface carried on said central portion of the top of said ridge in close juxtaposition to and facing toward saidelongatedsurfacetoactasacathodeincooperation therewith, means for heating said emissive surface by the use of an externally supplied electrical current, said means including a resistive filament and a heater lead connected to oneoftheendsthereofand extendingto aterminal on the outside of said envelope, said lead within the ridge between its top and bottom to be shielded therewithin and extending through said opposite side of the section of wave luide to said terminal.

17. An electron discharge device comprising an elongated hollow conductor, an elongated conducting ridge extending longitudinally within said conductor. one transverse dimension of said ridge beingalnsostasgreatasthecorrespondingdimension of said conductor. at least one side edge ofsaidridgebeinglocatedinclosespaced relation with said conductor, the transverse dimensionofsaidrldseatrlght anslestosaidnrstnamed being only a small fraction of the vlc. l ls s K tominimil'ethereductionoftheimpedanceof said conductor due to the presence of said ridge. andea cathode supported on said side edge of said HARWICK JOHNSON. KENNETH R. DE REMER..

BefereneesCitedintheiileofthispatent UNlTlliDB'I'ATESPAmTB Number Name Date 2.122.538 Potter July 5, 1938 2.144.322 Heumann Jan. 17. i939 2.157.952 Dallenbaeh May 9, 1939 2,402,184 Samuel June 18. i946 2.463.308 Finke Mar. 1. i949 2.500.644 Johnson May 9. 1950 2.509.374 Bunnein May 30. 1960