US2457194A - Microwave oscillator - Google Patents

Microwave oscillator Download PDF

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Publication number
US2457194A
US2457194A US2457194DA US2457194A US 2457194 A US2457194 A US 2457194A US 2457194D A US2457194D A US 2457194DA US 2457194 A US2457194 A US 2457194A
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electron
oscillations
mode
frequency
chamber
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/10—Magnet systems for directing or deflecting the discharge along a desired path, e.g. a spiral path
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/06—Tubes having only one resonator, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly velocity modulation, e.g. Lüdi-Klystron
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
    • H01J25/12—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator with pencil-like electron stream in the axis of the resonators

Definitions

  • This invention relates to microwave oscillators ahd'more particularly to oscillation-producing systems utilizing electron velocity variation apparatus and resonant chambers for producing oscillations in the centimeter wavelength range.
  • Resonant chambers or cavities as they are commonly termed, have many advantages for use in oscillators in the microwave art.
  • Resonant chambers or cavities as they are commonly termed, have many advantages for use in oscillators in the microwave art.
  • a principal object of the' invention is to enable an oscillator employing resonant cavities to operate at one of the higher modes free from the disturbance and loss attendant upon oscillation at a graver mode.
  • Another object of .the invention is to inhibit the operation of a cavity resonator at its gravest frequency while permitting it to operate freely at a frequency of a higher mode.
  • a microwave oscillator utilizing one or more resonant chambers is operated at a frequency higher than that of the gravest mode which any of the chambers will support.
  • a microwave oscillator utilizing one or more resonant chambers is operated at a frequency higher than that of the gravest mode which any of the chambers will support.
  • One expedient for suppressing oscillations of the gravest mode relates to choice of the impelling eiectromotive force applied between the electron source and the collector of the principal electron'beam' If the magnitude of that electromotive force be so chosen that the transit time for the drift space between the .velocity variation gap and the energyderivation gap is correct fora' higher mode oscillation but is not correct for the gravest mode of oscillatiomoscillations of" the higher frequency will be sustained but 5 Claims. (cram-s) those of the gravest mode will be inhibited. In some instances it may be desirable to inhibit several of the graver modes of oscillation and by suitable chcice of the electromotive force this may be done. I
  • An alternative expedient is the use of a feedback path, thepath, beingso designed that its frequency transmission rangexpermits only oscillations of higher than the gravest mode or of higher than 'a few of the 'graver modes to freely pass.
  • lt' feature of'the invention is the use of a variable; magneticneldto focus the electron beam at a chosen point in its course. This is eflected by .a' permanent magnet structure which comprises the resonant chamber itself. Variable magnetic'shunts'enable the magnetic field strength to whi'chjthe beam is subjected to be varied as desired.
  • FIG. 1 illustrates diagrammatically a microwave oscillator of the single resonance chanibertype in which oscillations of the gravest modeare inhibited by selection of the electron impelling electromotlve force.
  • Fig.1 illustrates in similar manner a. tworesonat'or oscillator with a wave guide feedback path which'iin'hlbits oscillations of the gravest mo'de.
  • Fig. 4 is a cross-sectionalong the line 4-4 of Fig. 3;
  • Fig. 5 shows a two-chamber oscillator in which selection of' a higher order mode of oscillation and inhibition of the gravest mode is effected by'choice of force.
  • Fig.'6 is-a modification of the disclosure of Fig. 3. in which the internal wave guides are replaced by, aperture or iris couplings.
  • an electron discharge device il comprises an evacuated container I! of .dielectricmaterialenciosing an electron gun l3 of any suitable type 'anda cup-shaped electron collector ll which maybe of graphite or other appropriate materlaL' Sealed through the walls ofthe cont'ainer.'.'l2 are the conducting discs i8 and lQ-eachapertured at the cen er as indicated to permit the passage of a beam of electrons therethrpugli fromthe gun I. to the collector ll. Between the discs I! and II is a cylindrical conducting rnember .ll with end apertures aligned withith'e' aperture: in the discs I!
  • the member ll prothe electron impelling electromotive vides a substantially field-free drift space of well-known type between the gaps l8 and I8.
  • the two-part shell 20 consisting of permanent magnetic material.
  • any suitable permanent. magnetic material maybe used as. ⁇ on example the silos disclosedin. the patent to Jonas 2,295,082, September 8, 1942.
  • the magnetic material of the cavity resonator, shell may be permanently magnetized with the central portion immediately adjacenhiha outer periphery of disc I!
  • the shell 20 may preferably be divided along a diametrical' plane passingthrough the longitudinal axis of container ii to permit ready assembly Clamps 2
  • The. drift space member I? is SUPPOl'tBd-DZM8J11G. rods 22. eachattachedtothe. member. i]. at on Ill" end andanchoredatthecppositacndiimthe well oiltheinsulatinacontainer l2; Meadllpassinlthrough an. insulating head 25' in. the shell 21L serves. to. electrically. connect. themeniber I]. to an external circuit.
  • a source of electromotive. iorca 25, provided with. potentiometers Hamill may serve team the customary, polarizing potentials, to.the.- electron. gun. 11,. electron. collector l4. and. the. rose nantcavitycver loads 2). "land 3ll.,reaneotivels. As is. well understood. inthia art. abeam. oi. sled-- tronsproceed ns irnmthccunli. is subjected. at.
  • Accordlnalntheanparatus serves. to produce. oscillations, ol'. (mommie determined principally by thernonancecharaca teristics of. the. r sonance. chamhsn. mement produce sustained oscillations it is essential that. the groupsor. bunches oielectronsarrlvingptthe c p it reach it atsu htlm atm omthe. whole. they will deliver more.energy,-t .t a elactromas; nctic fleldthan they, abstract from. it. lttranspires, therefore, that with a liven electromotiveiorce impressed by. the. source ll between.
  • Applicant has found that wituaparticiilar ll paratus beginning witnan elcctliomojillajprcemff 500 volts, applied between source. I) and colltst r It d srauualiy incressi r. that. electromotiva force that at. 800 volts oscililtionaotifio. contiameters wavelength corresm lnr. to the Bravest. mode. oi oscillation oi" t ercsonant cavity were. obtained. Calculations showed. that. the. ciriift.
  • time between the velocity varying gap and the energy extraction gap was approximately 1.75 cycles.
  • the oscillations disappeared until at a point in excess of 1000 volts oscillations of 10.25 centimeters corresponding to a higher order resonance mode of the resonant. cavity. were obtained.
  • Further increase in voltage caused the oscillations 01 10.25 centimeters wavelength to be suppressed and at a -.point below 2500 volts oscillations of 7.65 centimeters wavelength were obtained.
  • the invention' therefore, enables very short waves to be produced with av device of such physical dimenslums s.- to lend. itself readily to manufacture.
  • dlillculty in the-tit. is. 01. sumcient. magn tude to enable. customary. tuning. appliances. to. be. utilized nd the. amount by which they change the. resonance f equencies. 01. the chamber. may readilybe. made comparatively small.
  • reliance for. tuning is .hadjprlmarily upon. one. or. more tunlns. p u s. 32. of well-known. im It has been explained. that. selection of a desired hig er resonance. frequency and s ppression oi. sra cr. mode oi: oscillation may be had. by the. p p hoice or imp llins.
  • the tendency of an electron beam after leaving the cathode or electron gun is to diverge. If this occurs to an undesirable extent a large portion of the beam may be so spread out as not to pass through the aligned apertures and thus to be intercepted before doing useful work at the gap l9.
  • a concentrating or collimating magnetic field Preferably, the field should be of such strength as to enable substantially all of the electrons to traverse the gap IS.
  • the reaction between electrons and the electromagnetic field in their transit across the gap is enhanced if the electron passes very close to the margins of the gap apertures or, in other words, to the perimeter oi. the circular openings at the extremities of the gaps.
  • the magnetic field is produced by the shell 20 of the cavity itself which consists of permanently magnetized material.
  • a plurality of external shunts comprising U-shaped strips 34 and 35 of soft magnetic iron material, the free ends of which closely engage the external walls of the shell 20 may be employed. As these are moved inwardly toward the dielectric container l2 they tend to divert the magnetic field from the gaps. As they are drawn outwardly they permit increase of that field.
  • the resonance characteristic of a closed chamber of conducting material depends to a considerable extent upon the nature and conductivity of its interior surface. In order to maintain energy loss in the chamber at as low a point as possible it is desirable that the interior surface have a very high conductivity. Moreover, in the case of a shell of magnetic material it is desirable to lnterpose a conducting screen between the internal electromagnetic field and the magnetic material in order to reduce hysteresis loss at the surface of the material. Accordingly, a coating or plating SI of highly conducting material such as copper or copper overplated with silver may be provided. The internal surface and a portion of the circular periphery of tuning plugs 32 may be likewise plated for the same purpose.
  • Fig. 2 discloses an oscillation-producing apparatus in which the electron source, the electron collector and the polarizing source are designated as in Fig. l. Positioned with their apertures in alignment with the electron beam passing from source I3 to collector l4 are two toroidal cavity resonators 36 and 31 physically connected by a tubular conducting member 38 which encloses the drift space between gaps 38 and 40. A plurality of tuning plugs 4i, 42, similar to plug 32 of Fig. 1 may be provided for each of the chambers 38 and 31. Connecting the chamber 31 to the chamber 36 and coupled to each of these chambers by predesigned aperture or iris openings 43 and 44 is a wave guide 45.
  • the coupling irises and the wave guide are given such dimensions as to freely pass oscillations of a frequency corresponding to a desired higher order resonance of the chambers 38 and 31 but to suppress oscillations of the gravest resonance mode of these two chambers.
  • Variable tap 48 enables the polarizing potential applied to the chambers and 31 and to the drift chamber 38 to be appropriately selected.
  • the electron beam passing gap 39 is subjected to a velocity variation after which, in the course of transit through the drift space of chamber 38, it becomes charge density varied so that at gap 40 it may react with the electromagnetic field within chamber 31 to yield energy thereto.
  • Oscillations of a desired frequency higher than that of the gravest resonance mode are fed back by the wave guide which I precludes feedback of the graver mode oscillations. In this manner, sustained oscillations of the desired frequency are produced.
  • Energy of the desired oscillation frequency may be withdrawn from the resonant output chamber 31 by an output coupling loop 48 and a coaxial output circuit 48 as in the case of Fig. 1.
  • Fig. 3 discloses a modification of the apparatus of Fig. 2 in which the velocity varying chamber 50 and the output energy chamber 5
  • Each of the chambers is provided with a plurality of tuning plugs 55.
  • a plurality of tubular openings 56 as indicated in Figs. 3 and 4 pass through the disc 53 and serve as wave guides to feed back energy from resonance chamber 5
  • These wave guides may be designed in a manner similar to the wave guide 45 of Fig. 2 to freely permit passage of oscillations of a desired higher order resonance mode and to preclude feedback of oscillations of the gravest resonance mode of either chamber. It will be understood that, as in the case of Fig. 2, the two chambers may be tuned to have substantially the same resonance charac-- teristics by means of the tuning plugs 55.
  • Fig. 5 discloses an oscillating system in which two resonance chambers 51 and 58 may be substantially identical in design with the resonance chambers 36 and 31 of Fig. 2.
  • the tuning plugs 59 are in this instance shown at the ends of these structures rather than at their outer peripheries as in Fig. 2.
  • a coaxial feedback line 60 having terminal coupling coils 6i and 62 serves to feed back output energy from chamber 58 to velocity varying chamber 51.
  • the coaxial line 60 may be designed to transmit oscillations of the entire gamut of resonance frequencies of the two resonance chambers.
  • variable contactor 63 of potentiometer 64 may be positioned in accordance with the principle presented in detail in the discussion of Fig. l to predetermine the transit time of electrons traversing the drift space within tube 38 between gaps 65 and 6.3 so that oscillations of the gravest mode will not be sustained but oscillations of the desired higher order frequency mode will be sustained.
  • Fig. 6, like Fig. 3, comprises a central metallic shell 52- divided intotwo resonance chambers 50 and 5
  • a thin-walled disc 89 is utilized. In this disc are apertures or irises 10 which correspond in function to the wave guides 58 of Fig. 3. The manner of design of such irises or apermemos titres "to permit transmissionitherethrough ot os cillations 01 a: desired frequency' whilez at the: sunshine; precluding: transmission ofloscillations oi substantially lower frequency is well under--- stood in the art.
  • Eacl'r'ofthe' resonator chambers disclosed no the" various figures oi the drawing 1 may have itsinterior coated with low'resistance material as in'the-case of Fig. 1-.
  • eachoi theresonator chambers may'consist oi'permanently' magnetized magnetic material to'assist in colli mation'oi the electron beam:
  • the electron source l3 ' whichhasbeen referred to-vari'ously'as a source ora' gun may beoiany' well-known type as mayal'so the'el'ectron' co1'-- iector M.
  • An oscillator comprising an electron" beam.
  • apparatus including a source of an electron beam, 2. cavity resonator having a gap adjacent the path of the beam to vary the electron velocities irr'the' beam, a second cavity resonator'havin'g'a' gap'adiacent the path of the beam at a point of density variation therein to receive energy from the'beam, said resonators having their gravest mode or'operation' at substantially'the same-irequency and means coupling the second resonator to'the first for feeding backenergy thereto, said. coupling means having a transmission frequency range which is limited to frequenciesconsiderably above the frequency of the gravest mode whereby oscillations of a higher mode are produced and oscillations of the gravest mode are inhibited.
  • a microwave source comprising an electron discharge device including an electron gun, an anode, a source of eiectromotive iorce connected therebetween, a pair oi cavity resonators'each having an aperture adjacent the path of'the beam oi electrons which proceeds from the gun to the anode whereby the electromotive force ot'the field oi the first of said resonators serves to vary the velocities of passing electrons and the electromotive force oi the second of said resonators reacts with the passing electron beam to derive energy therefrom, means coupling said resonators together, said coupling means having a transmission frequency range which lies entirely above the gravest frequency mode of either resonator whereby only oscillations 0! a higher mode may be produced and one of said resonators having means connected therewith ior tuning the resonator toenable it to operate at high efficiency at the same frequency as the other resonator.
  • An electron discharge device comprising two toroidal cavity resonators oi conducting'materiai,
  • Am-electron' velocity variation device com-- prising arsource 0t electrons, an electron collector and an electrical: resonant syi'stem connected thereto comprising an external' hollow cylinder oiconductingrmaterial, an internal hollow"- cylinder of conducting: material fixed in coaxial: position within:.the externalrcylind'er by an annular'walli ofrconducting material which divides the external: cylinder longitudinally into two cavity resonators; the: ends at both-the external andi the: internal cylinder: being apertured at points aligned witln the path: of the:electron beampassing front-the" eiectrom source to. the: electron collector; and: coupling.
  • An electrondischarge device comprising electron gun; an. anode; .a source 05 Ieiectromotive: force connected therebetween,lmeansaforming two cavity resonators-z longitudinally spaced betweem said electron gun and said anodeeach' resonator. having. an aperture adjacent-thepath of'the beam of electrons whichproceeds Irom'the! gun to the.

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  • Control Of Motors That Do Not Use Commutators (AREA)
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US2457194D 1943-06-23 Microwave oscillator Expired - Lifetime US2457194A (en)

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US (1) US2457194A (en, 2012)
FR (1) FR938639A (en, 2012)
GB (1) GB597511A (en, 2012)
NL (1) NL68012C (en, 2012)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2561398A (en) * 1945-04-23 1951-07-24 Standard Telephones Cables Ltd Coaxial line circuits
US2577971A (en) * 1947-05-14 1951-12-11 Rca Corp Microwave cavity resonator device
US2871397A (en) * 1955-03-18 1959-01-27 Eitel Mccullough Inc Electron tube of the klystron type
US2928972A (en) * 1954-04-09 1960-03-15 Varian Associates Electron tube apparatus
CN114792903A (zh) * 2021-01-25 2022-07-26 住友电装株式会社 连接器

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2108900A (en) * 1934-11-08 1938-02-22 Rca Corp Ultrashort wave oscillation generator circuit
US2167201A (en) * 1935-06-28 1939-07-25 Pintsch Julius Kg Electron tube
US2280824A (en) * 1938-04-14 1942-04-28 Univ Leland Stanford Junior Radio transmission and reception
US2281935A (en) * 1938-04-14 1942-05-05 Univ Leland Stanford Junior Modulation system
US2305884A (en) * 1940-07-13 1942-12-22 Int Standard Electric Corp Electron beam concentrating system
US2317140A (en) * 1940-05-28 1943-04-20 Int Standard Electric Corp Electron discharge apparatus
US2323735A (en) * 1940-03-14 1943-07-06 Westinghouse Electric & Mfg Co Electric discharge apparatus
US2323560A (en) * 1940-07-05 1943-07-06 Int Standard Electric Corp Electron discharge apparatus
US2379819A (en) * 1941-03-07 1945-07-03 Bell Telephone Labor Inc Frequency modulator
US2404279A (en) * 1941-08-07 1946-07-16 Rca Corp Ultra short wave system
US2408409A (en) * 1941-04-08 1946-10-01 Bell Telephone Labor Inc Ultra high frequency electronic device
US2409608A (en) * 1941-09-24 1946-10-22 Bell Telephone Labor Inc Ultra high frequency detector

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2108900A (en) * 1934-11-08 1938-02-22 Rca Corp Ultrashort wave oscillation generator circuit
US2167201A (en) * 1935-06-28 1939-07-25 Pintsch Julius Kg Electron tube
US2280824A (en) * 1938-04-14 1942-04-28 Univ Leland Stanford Junior Radio transmission and reception
US2281935A (en) * 1938-04-14 1942-05-05 Univ Leland Stanford Junior Modulation system
US2323735A (en) * 1940-03-14 1943-07-06 Westinghouse Electric & Mfg Co Electric discharge apparatus
US2317140A (en) * 1940-05-28 1943-04-20 Int Standard Electric Corp Electron discharge apparatus
US2323560A (en) * 1940-07-05 1943-07-06 Int Standard Electric Corp Electron discharge apparatus
US2305884A (en) * 1940-07-13 1942-12-22 Int Standard Electric Corp Electron beam concentrating system
US2379819A (en) * 1941-03-07 1945-07-03 Bell Telephone Labor Inc Frequency modulator
US2408409A (en) * 1941-04-08 1946-10-01 Bell Telephone Labor Inc Ultra high frequency electronic device
US2404279A (en) * 1941-08-07 1946-07-16 Rca Corp Ultra short wave system
US2409608A (en) * 1941-09-24 1946-10-22 Bell Telephone Labor Inc Ultra high frequency detector

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2561398A (en) * 1945-04-23 1951-07-24 Standard Telephones Cables Ltd Coaxial line circuits
US2577971A (en) * 1947-05-14 1951-12-11 Rca Corp Microwave cavity resonator device
US2928972A (en) * 1954-04-09 1960-03-15 Varian Associates Electron tube apparatus
US2871397A (en) * 1955-03-18 1959-01-27 Eitel Mccullough Inc Electron tube of the klystron type
CN114792903A (zh) * 2021-01-25 2022-07-26 住友电装株式会社 连接器

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NL68012C (en, 2012)
FR938639A (fr) 1948-10-20
GB597511A (en) 1948-01-28

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