Dec. 24, 1946. D. G. CLIFFORD ETAI. 2,413,171 SWITCH Filed oct. s, 1942' I 2 sheets-sheet 1 Dec. 24, 1946. - D. G. CLIFFORD ETAL SWITCH Filed 0015. 8, 1942 3.1 2,413,171 l 2 Sheets-Sheet 2 34 INVENTORS .Q G-Cl/FFÚÉÜ E C'. a/f/ÈE'SS . MW@ MAM hm. ATTORNEY Patented Dec. 24, 1946 ~ 2,413,171 UNITED STATES PATENT OFFICE v -2,413,171 ' . SWITCH David Gordon Clifford and Ernest C. Qkress,Montclair, N. J., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 8, 1942, Serial No. 461,336 8 Claims. 1 In its broader aspect, this invention relates to receiving and transmitting energy in the form of electro-magnetic waves and more specifically it relates to» a novel switch which is connected be tween the transmitter and receiver and serves the purpose of protecting the receiver during the transmission pulse. (Cl. 178-44) 2 box meeting the exacting requirements outlined above and with greater eiîectiveness than ac complished by devices of the prior art. » More specifically, an object of the invention is to provide a TR box with a cartridge type elec trode assembly. ` Another object of the invention is to localize the Use of reflection cf radio waves for various pur lecessary evacuated region, and to require par poses, such as determination of altitude of an tial Vacuum only within the cartridge. airplane to ground, for locating one airplane from 10 A further object of the invention is to provide a ano-ther or from a ñxed situation, and for other tunable TR box with‘the electrodes and cartridge purposes, is an acknowledged fact. The wave is envelope maintaining an undisturbed relationship generated, passed to the antenna and into space, and with the partial vacuum undisturbed. reflects from the object addressed, returns to the A still further object of the invention is to uti antenna and thence to the receiver. A switch of 15 lize moving parts for tuning purposes entirely out automatic character has to be provided to keep side of the cartridge. the projected pulse from passing through the re Again, an object of the invention is to provide a ceiver at the time of projection but which will per cartridge construction which is readily removable mit the reflected pulse to operate the receiver. and replaceable and necessitates minimum mate Such va switch is now commonly referred to as a 20 rial and labor loss represented by the substitution. “TR box.” Another object is to provide for proper orienta The present invention is directed primarily to tion of the cartridge in the resonator and also to an improved TR box capable of use with a wave establish desired resonance mode. guide. The term “wave guide” is used to describe Still further objects of the invention will appear the means by which electro-magnetic energy is 25 as the description progresses, both by direct reci propagated in hollow tubes from one place to an tation thereof and by implication from the con other before its ultimate transmission into free text. space, if that is to be done. More specifically, a Referring to the accompanying drawings in wave guide includes the provision of a dielectric, which like numerals of reference indicate similar such as air within a channel, the wave guide ex parts throughout the several views: tending from place to place and constituting a Figure 1 is a sectional view longitudinally metallic boundary laterally engirdllng the dielec through a TR box and associated wave guide, as tric. The cross-sectional dimensions of the me on line I-I of Figure 2; tallic boundary of the wave guide have a delinite Figure 2 is a sectional view longitudinally of the relation to the character of the wave transmitted .‘ en wave guide and transversely of the TR box, as thereby. Literature has employed and this de upon line II-lI of Figure 1; scription will correspondingly employ the letter a Figure 3 is an elevation of the cartridge struc to designate the short dimension and letter b to ture utilized in our improved TR box; designate the long dimension of the cross section Figure 4 is a longitudinal sectional view of a of a rectangular wave guide. In the present speci 40 modified construction of cartridge; fication selection of a particular mode is employed for simplicity, and by arbitrary choice herein that propagation of electro-magnetic energy isi by Figure 5 is an elevation of the TR box or switch ' in its associated relationship with transmitting and receiving apparatus; means of the H01 wave. It is to be understood, however, that-other modes may be used and other shapes and" dimensions of wave guides maybe Figure 6 is a sectional View similar to Figure 1 showing a modified choke construction; and employed. Figure 6. ' The degree of delicacy of operation of the TR box is highly important as itis essential that the Figure 7 is a cross section on line VII-VII of In the speciiic embodiment of thev invention illustrated in said drawings, reference is ñrst high power of the outgoing signal shall notpa'ra 50 made to Figure 5 wherein is illustrated the gen lyze or even filter through tothe receiver, and yet it is imperative that the faintest of reflected sig nals shall pass through the switch to the receiver. The present invention accordingly has for its primary object the provision of a switch or TR 55 eral assembly of apparatus comprising a wave generator i9 productive of high pulse energy of desired frequency promulgated as Hoi' waves lon gitudinally of a wave guide Il preferably of rec tangular cross section. Such waves may be dl 2,413,171 3 from the wave guide or through the agency of an antenna, such as a horn, or otherwise. Pref erably the waves are sent forth from a parabolic tridge comprises essentially a long tubular en velope 2l Within which are situated cylindrical device, which for brevity and ease of reference will be termed an antenna I2 which can be moved electrodes 22, 22 opposed endwise toward each about for directing the wave path o'r beam` in a other on a common axis and coaxial with the en desired direction and toward an object. The in vention is preferably used in conjunction with. velope. The outwardly directed ends of the elec# trodes are mounted upon lead-in wires 23, 23 of sufficient rigidity to maintain the electrodes in the position shown with a gap 24 between the ultra-high frequency radio waves, an advantage of which is the property of straight-forward pro' jection and reflection in substantially the same inwardly directed. ends, said ends preferably manner as light waves. Accordingly, the- pro jected wave energy directed toward some object, such as an airplane, reflects therefrom and on being somewhat pointed. The glass of the en velope 2I is sealed around the lead-in wires, the envelope is evacuated, reiilled with ionizable gas if desired: to appropriate pressure, and tubulation 25 for. that purpose sealed oiî. The cartridge is mounted to be removable in its entirety and re placeable at will, and in use should be situated symmetrical with respect to the center line of the wave guide,`that is, the centerline of the wave guide should be normal to and pass between the inwardly directed ends of the electrodes. The glass tube 20 is of adequate internal volume to maintain long life of operation. Projecting outwardly from the fixed end I8 of the resonator body is an inverted cup 26 of cylin drical shape and having an outer end 2'I‘from which'projects a neck 28. Said neck is coaxial its return course between pulses is intercepted by the antenna I2 which concentratestheA wave to re-enter wave guide I I and travel therein and through a branch wave guide I3 to a receiver I4' which is then excited by the returned Wave. The generator is placed at a speciñed distance from the junction of wave guides II and I3 so as to present such an impedance at the junction (in the quiescent state) so as to divert the received energy toward the receiver in guide I3. Ob viously the returned wave energy will be very weak as compared to the high power of the en ergy produced by the wave generator. The TR box I5 is interposed in branch wave guide I3 be tween the receiver and generator and between the receiver and the antenna to automatically prevent the high power energy from generator I0 during transmission from destroying or inter fering with the receiver and yet permitting the receiver to be actuated in consequence of the relatively weak power of the returned' signal be tween pulses. 4 tures open. Coaxial with and within the cylin drical resonator body is situated, in use, the re movable and replaceable cartridge 20 constitut ing a feature of the present invention. The car rectionally transmitted into free space directly with the' said cup which in turn is coaxially alined withv the cylindrical body portion I6. Said cup furthermore is provided with an axial bore for receiving one of the lead-in wires 23 of the car~ - tridg'e. When the cartridge is adjusted to its de sired position a set screw 29 projecting radially The switch or TR box of the present invention inward of the neck is employed for clamping the lead-in wire at such position. It will now be clear that insertion, removal, and replacement, as well as adjustment of the cartridge, may be read 40 I6 which is hollow and in part provides a reso ily eiîected. nator chamber Il> therein'. The body I6 is pro The bottom wall 30 of the resonator, that is. vided with a fixed end wall i3 which is situated the wall opposite from the iixed end wall I8, is in the plane of the long dimension wall b of the made adjustable. For that and other purposes branch wave guidev I3, the said body I6 extending said bottom wall is made integral with a cylin from 'said fixed end> wall I8 of the wave guide, drical section SI coaxial with and spaced in transversely through the hollow of the wave guide wardly from the body portion I6, the hollow of and out through the opposite long dimension wall this cylindrical section affording the necessary b of said wave guide. Apertures, closed by win region for introduction of the cartridge to its dows I9 of material transparent to the wave en desired position within the resonator. At the ergy are provided at parts of the resonator body outer peripheral face of the said cylindrical sec within the wave guide and centered upon the tion intermediate the ends thereof is a flange 32 center line of the wave guide. The windows are the 4outer peripheral face whereof is screw of suitable dielectric material, such as low loss threaded, as at 33, and is engaged with corre glass and serve as means for passing the flow of sponding screw threads on the interior periph wave energy in the guide through the resonator. i eral face of body portion I6. The outer end of Said windows are suitably dimensie-ned both as to the cylindrical section 3| is formed with a cap diameter and thickness and with due considera 34 thereon said cap having a rim portion 35 tion to their dielectric constant, to introduce a which overlies the outer peripheral wall of the minimum of disturbance and still give sufficient body portion. Said cap constitutes a convenient coupling between the resonator chamber and the GI) finger hold by which the same may be manipu wave guide. These window apertures are shown lated and it will, therefore, be clear from the circular, though they need not be, andrconcentric above that rotation of the cap will obtain a cor preferably comprises a cylindrical body of metal with a diameter of the resonator as well as with responding rotation of the cylindrical section and the center line ofthe wave guide. The windowed its threaded flange thereby advancing or retract apertures are preferably as small as practicable 65 ing the movable end wall 3l] depending upon di i‘or still obtaining desired energy transfer with rection of rotation. Movement of the adjustable out undue lessening of the surface continuity of end wall 3B is for purposes of tuning the resona the resonator. The area of the windows to a con tor. siderable extent controls the coupling coeñìcient, Electrical continuity is necessary between- the detailed discussion of which is out oi.'` place here'. adjustable wall- 30 and the cylindrical wall of Since neither the resonator nor the. wave guide, the resonator, but sliding contact at the periph in accordance with preferred construction, are e'ry of the said end wall is highly objectionable. evacuated, there is no need for the windows to The construction employed accordingly spaces the be vacuum tight, and it is within the scope of the invention to omit the windows- and leave the‘aper- ' periphery of the adjustable end wall slightly in 5 2,418,171 6 ward from the surface of the body portion of the resonator, leaving a gap 36 thereat. From the peripheral edge of the adjustable wall next the said gap, a skirt 31 projects rearwardly from the resonator said skirt being cylindrical and having energy ycan pass substantially unattenuated to they receiver. ' In greater detail this means that some spark mechanism is placed inthe resona tor which is ineiîective during small signals or small pulses and allows the energy to pass a depth equal to a quarter wave length in the through substantially unattenuated. On the other hand, however, during the time when the medium involved, which in the present showing is air. The adjustable wall 3B and skirt 3l ac generator l0 is operating and/or a large pulse is cordingly constitute a piston, opening away from the resonator and setting up a high impedance 10 at the open end. In consequence of the quarter wave length depth, high impedance at one end results in low impedance at the other end so that there will be low impedance at said gap 36 which wave energy recognizes as equivalent to contact between the surfaces and, therefore, con stitutes electrical continuity without actual con tact. This construction is referred to herein and in the trade as a choke. yElectrical continuity between the adjustable wall 30 and its adjacent electrode 22 and be tween the fixed wall I8 and its adjacent electrode 22 is obtained by a choke in a manner similar to that above described with respect to the adjust able wall and resonator body. The construction of choke accordingly provides a metal ring 38 for the ñxed wall I8 and a metal ring 39 for the adjustable wall 30 of the resonator, both said rings projecting outwardly from the resonator and having an inside diameter of appropriate size for permitting the cartridge to loosely pass there through. Ring 38- is likewise smaller than the cylindrical wall of cup 26 so there is an annular space therebetween. This space is iilled with a glass or other dielectric ring 4I) having the same . loss tangent and real dielectric constant as the glass of the cartridge envelope. Similarly, ring 39 is spaced inwardly from cylindrical section 3l leaving an annular space therebetween which is ñlled with a glass or other dielectric ring 4I also having the same loss tangent and real dielectric constant as the glass of the cartridge envelope. Each metallic ring 38 and 3,9 has an axial depth equal to a quarter wave length in the medium em ployed, which in the present instance is glass. ‘i. ‘ Observation is made at this time, that the wave length in a dielectric such as glass is materially shorter than in air, and in the present showing, length of the metallic rings 3B and 39 represents received, the spark gap discharges, reducing the Q of the resonator, and blocks the large signal there, cutting down the transmission through the TR box to protectiveV values; This discharge oc curs during the high pulse because a very high electric gradient is set up between the spark gap electrodes properly positioned in the resonator. The use of such a spark gap in the cylindrical resonator containing the sparkgap electrodes coaxial -with its axis will not permit an easy corn putation of the resonant frequency of the system. As 'it'has been found that there is a time lag, inñnitesimal though it may be, in the high ñelds becoming effective to break down the gap be tween electrodes 22,22 it becomes deiinitely de sirable to obtain greater promptness in this re spect. Generally speaking for the moment, this objective is attained by utilizing an ionizable gaseous medium‘in the resonator and a keep alive therein by which a gas ionization is main tained and thereby supplying the desired ionizing radiation across the gap. Consequently when resonant potential builds up across the gap the moment of breakdown of the gap is accelerated, thus reducing the time lag in operation. Ac cordingly, the resonator body is ñrst evacuated after which approximately one millimeter (or more if desired) of an appropriate gas is. ad mitted. Suitable gases for the purposes include hydrogen, nitrogen, with or Without water-Vapor, as well as other gases alone or in combination. For keep-alive purposes, one of the electrodes is rendered emissive. As. shown in Figures 1 to 3 the inner end of one electrode has a‘radio-active or gamma emission' material thereon, such as radium, as indicated yat 41.' `Otheri'formsí’of keep-alive electrode may be provided, and in Figure 4 is shown a construction wherein glow discharge is obtained by a structure utilizing external potential for the purpose. Some -rn'odiilcatiorí of the envelope is likewise a single quarter wave length for the glass dielec- 5'1 involved. In this showing oneelectrode 22' dii" tric as compared with the depth of the piston fers `from electrode 22 in that it is hollow or wall or skirt 31 heretofore described which rep tubular and has therein a rod or wire 42 which is resents a single quarter wave length in air. As a continuation of its lead-in wire 23. This rod explained above, high impedance at an open end extends to the forward end of electrode 22’ so means there must be low impedance a quarter a as to be at the forward opening of the electrode wave length distant where the rings are attached but without making contact therewith. Rod 42 to their respective end walls, wherefore, for >the wave energy involved, there is electrical continu ity thus obtained between the said end walls and the adjacent electrodes at the ends adjacent to le' the resonator I1. It may be here added that all parts above described, except those specifically referred to as glass or dielectric, are of suitable metal such as brass, copper and the like, to be electrically conductive. may be of electron emissive character, such as tungsten-oxide-barium, tungsten-barium, stron tium-barium and the like. The envelope 2 I ’ next the tubular‘electrode 22' is sealed to a metallic tube 43 of substantially the same diameter and the electrode 22’ is ñanged as at 44 next its outer end so` asy to fit this metallic tube for support and centering thereby. The flange 44 may be secured in place within the tube by soldering as at 45. In 'performing its function as a TR box, the resonator is constructed and positioned with re spect t0 the junction of the wave guides II and Beyond the ilange the lead-in wire 23 is sealed within the metallic tube by a glass bead 46. Po tential diiïerence between the tubular electrode I3 so as to present such, an impedance at the and the rod 42 may be applied through the metal junction to provide electrical continuity through f' I' lic sleeve 43 and the lead-in wire 23. the guide ,II during transmission and prevent leakage of power above a safe value to the re ceiver and furthermore to provide a suitable im. In the _foregoing description, it will be vobserved that an important lfeature is the provision of á. quarter wavelength of coaxial lines by metallic pedance at the junction during the period of re rings 38, 39 in conjunction with the electrodes 22, ception (generator quiescent) so that the received 75 to secure eiîective' electrical connection through 2,413,171` not affect the gap 24 between the electrodes` at. all. Since the various details of construction, asf well as the precise relation and functioning of parts, are subject to variation and change with out departing from the inventive concept or scope of the invention, it is intended that all matter contained in the specification or illustrated in the the glassv of envelopev 2‘ll at the desired placchetweenthe electrodesand the body of the, resonant; chamberV l 1. The structure thus far described has the advantage of overall limitations of length by use of relatively short chokes by virtue ofthe hollows of the chokes being filled with the dielectrics 40 and 4l .with the dielectric the same, drawings, shall be interpreted as exemplary and not in a limiting sense. t is also to be under or having the same dielectric constant, asV the glass or wall of envelope 2|. The inclusion of glass as dielectric rings 39 and 40, however, in 10 stood that the following claimsA are intended t0 cover all of the generic and speciñc features cf the invention herein shown and described and all the nature of the material and the desirability of' statements of the scope of the invention herein obtaining a snug fit thereof in its appointed place. set forth as aL matter of language which might It is accordingly deemed within the scope of the be said tofall therebetween. ' invention to utilize other dielectricA than glass, We claim: and to vary the arrangement of the choke if l. A 'IR box comprising a non-evacuated en found desirable. A modified construction in this closure forming a resonant chamber having a respect is accordingly shown in'Figures 6 and 7. cylindrical side wall, and said side wall having In connection with the construction shown in Figures 6 and 7, those parts which are identical 20 window openings to the exterior of said chamber, and a cartridge structure insertable through said with parts heretofore describedA are identiñed by chamber, said cartridge structure comprising a the same reference numerals- and repetition of partially- evacuated envelope and electrodes sepa description thereof is omitted. As to parts which troduces certain difliculties in_fabrication, dueto are similar, the same reference characters with the addition of the` letter “a” thereafter are ap plied and the following description will set forth the differences so far as deemed necessary. ‘ rated by a gap within said partially evacuated envelope, said gap being substantially opposite said window openings. 2. A TR box comprising an enclosure forming a resonant chamber having opposed end walls Metallic rings 39a andv 40a are provided in this provided with openings therethrough, a cartridge modified. construction> of Figures 6 and 7, said rings having a quarter wavelength dimension 30 structure traversing said chamber past said. op posed end walls and projecting> through said open axially thereofY as in the previously described con ings, said cartridge having electrodes therein, and struction, but in this instance said rings do not means next said openings outside said end walls provide hollow spaces“ to> the next adjacent sur for establishing electrical continuity between said roundingV wall, but are solid> from their inner end walls and electrodes while maintaining phys 35 openings to said- surroundingv wall. ical separation thereof. Axially` outward from each said ring 39a and 3. A TR box comprising an enclosure forming 40a is a choke, each being constituted by a longi a resonant chamber and having a cylindrical wall, tudinal cavity 48 having a quarter wavelength a movable wall to said chamber for tuning to de dimension. in the axial direction, the wavelength dimension being referred to the dielectric of the 40 sired resonance, said movable wall being spaced from the said cylindrical wall, means for estab cavity, in this instance, in air. Said cavityy in lishing electrical continuity across said space, and each instance has a‘circular slot opening or gap a cartridge structure having a dielectric envelope 49 at the end next the metallicring and inwardly in part within said chamber and having elec toward the cartridge or envelope. (The effect of this choke isto introduce a high'impedance > trodes therein separated from each other by a gap -andadapted to destroy resonance in said res at the gap dsthereby forcing a low impedance at onant chamber, one of said electrodes being in the. far end therefrom ofY the metallic ring, part within said movable wall and the envelope namely at the end of the metallic, ring next the being interposed in part therebetween, and means resonator chamber.) Thus, both constructions for establishing electrical continuity between one obtain this desired low impedance across the gap electrode and said movable wall through said di and provide the eiîect" of electrical continuity electric of the envelope at the said part thereof between the electrodes andthe adjacent wall of interposed between said one electrode and mov the resonant chamber. able wall. ' The constructions sho-wn are accordingly both 4. A TR box comprising an enclosure forming of cartridge types, namely, longn and slender and a resonant chamber and having a cylindrical wall representing a minimum ofl evacuated volume. and end walls of which one is adjustable in an The cartridge can be insertedfat, the resonant axial direction of the cylindrical wall, said mov chamber of the-TR box, which chamber no longer able wall being spaced from said cylindrical wall, has to be of partial.vacuumtypeconstruction as inthe prior art. This isextremely-important be 60 means for establishing electrical continuity across said space, a cartridge structure having a dielec cause oftheprecisicn of part fabricationlrequired tric envelope in part extending through said end ofthe resonant chamber ofthe TR boxpand the walls and in part within said chamber and hav resulting high cost. anddiiflculty of fabrication ing electrodes therein separated from each other ifeach TR box is made as- a comp-leteand evac uated` integral unit; With a- TR. box of the> pres ent invention', any failure. of' partial vacuum or of theÍ discharge» electrode characteristics; can be readily repaired or altered by simplyf inserting a newv cartridge. It furthermore may be pointedout that an outstanding featurerof* the-:device ofthe f by a gap, said electrodes projecting in part through said end walls within the envelope and the envelope being in part interposed between said electrodes and said end walls, and means for establishing electrical continuity through said interposed part of the envelope between each said electrode and-the said end wall through which present invention is the abiiity> t0V arbitrarily-sc each electrode projects. . l‘ectf gap width for optimum operation> and this 5. A TR box comprising an enclosure forming gap will then be independentfof‘the wavelength-~ a resonant chamber and having a cylindrical wall controlling mechanism. More-specifically, it: is to and end walls of which one is adjustable in an 75 beA noted that tuning by rotation ofcap 35 does 9 2,413,171' axial direction of the cylindrical wall, an elec trode cartridge supporting means projecting from the ñxed end wall, and supporting and adjust ing means projecting from the movable end wall, both of said end Walls having openings axially therethrough for receiving an electrode cartridge inserted therethrough, both of said end walls hav for establishing electrical continuity through the cartridge structure from the electrodes to the respective walls of the resonant chamber through which said electrodes pass, said means constitut ing a choke for said electrodes whereby mode dis tribution is maintained in saidv chamber, said choke comprising a metallic ring and a solid di electric around said ring of a length equal to a ing quarter Wavelength rings neXt said openings projecting outwardly from the resonant chamber quarter Wavelength in the dielectric. for establishing electrical continuity at said open 10 8. A TR box comprising an enclosure forming ings with electrodes situated therein, a resonant chamber, a cartridge structure in 6. A TR box comprising an enclosure forming sertabie through said resonant chamber, said car a resonant chamber, a cartridge structure in tridge structure having electrodes each passing sertable through said resonant chamber, said car through a different wall of said enclosure, means tridge structure having electrodes each passing 15 for establishing electrical continuity through the through a different wall of said enclosure, and cartridge structure from the electrodes to the re means for establishing electrical continuity spective walls of the resonant chamber through through the cartridge structure from the elec which said electrodes pass, said means constitut trodes to the respective walls of the resonant ing a, choke for said electrodes whereby mode dis Chamber through which said electrodes pass, said 20 tribution is maintained in said chamber,v said means constitutingT a choke for said electrodes choke comprising a metalli-c ring having longi whereby Inode distribution is maintained in said tudinally therebeyond a circular gap toward the chamber. cartridge and providing a longitudinal cavity '7. A TR box comprising an enclosure forming communicating with said gap and extending lon a resonant chamber, a cartridge structure in gitudinally away from the said ring with a length sertable through said resonant chamber, said 25 equal to a quarter wavelength in air. cartridge structure having electrodes each passing DAVID GORDON CLIFFORD. through a different wall of said enclosure, means ERNEST C. OKRESS.