US2406372A

US2406372A - High-frequency apparatus

Info

Publication number: US2406372A
Application number: US393868A
Authority: US
Inventors: William W Hansen; John R Woodyard
Original assignee: Sperry Gyroscope Co Inc
Current assignee: Sperry Gyroscope Co Inc
Priority date: 1941-05-17
Filing date: 1941-05-17
Publication date: 1946-08-27
Anticipated expiration: 1963-08-27

Description

AUS-'27,1946 w. w.HANsEN E-rAL I 2,406,372 HIGHy FREQUENCY 'A 1= P.I\RATU-:

Filed May 17, 1 941 3 sheets-sheet v1 INVENTOR WILLIAM W. HANSEN M JOHN R. WOODYARD 5 Sheets-Sheet 2 INVENTOR WILLIAM W HANSEN dw( JOHN R. WOODYARD w. w. HANSEN ETAL HIGH FREQUENCY APPARATUS File@ My 17, 1941 Aug. l27', 1946.

FIG. 6

F ll-r 7 AugQ 27, 1946.

HIGH FREQUENCY APPARATUS Y A Filed May 17', 41 94 fs Shee's-sheet s A INVENTORS WILLIAM W. HANSEN Y JQHN FLWOODYARD l THEIR ATTQN'Y.'

Patented Aug. 27, 1946 HIGH-FREQUEN CY APPARATUS William W. Hansen an d John R. Woodyard, Garden City, N. Y., assignors to Sperry Gyroscope Company, Inc., of New York Brooklyn, N. Y., a corporation Application May17, 1941, .Serial No. 393,868

(Cl. 17E-44) 24 Claims.

This invention relates, generally, to the art of high frequency energy transmission and apparatus related thereto, and has reference more particularly, -to novel improvements in` impedance matching and transforming devices adapted for use with this type of apparatus operating at ultra-high frequencies, of the order of 109 cycles per second.

In transforming energy from one high frequency device to another, it is Well known that the Value of the impedances of the respective devices must be properly matched in order to avoid the production of standing waves with attendant increase in losses and decrease in the energy transmitting capacity of the system. Further, for maximum eillciency, it is known that the impedance of a load or utilization device must be properly transformed to match that of the source.

The present invention is principally directed toward the provision of improved impedance matching and transforming devices which are adapted to eflicien-tly couple and match the impedance values of the circuit elements interconnected thereby with a minimum of adjustment and a maximum of facility and efliciency.

In another of its aspects, the present invention is directed .toward a provision of a novel sliding joint utilizable in connection with the above-mentioned impedance matching and transforming devices, or, which may be employed generally in ultra-high-frequency coupling arrangements wherever adjustability and` smoothness of transition are desired.

A principal object of the present invention is to provide novel impedance matching means for matching the impedance of an apparatus of the above character to that of other apparatus, such impedance matching means being designed for versatile operation in that it may efciently connect two impedance elements havingimpedances of different values with high elciency of power ilow therebetween. Y i l A further object is to provied novel impedance matching means which is so designed as to efciently match both the resistive and reactive components of any two impedance elements having generally different impedance values.

Another object is to provide novel and eilicient sliding joints for telescoping concentric transmission lines, whereby reflections and standing waves are prevented.

A still further object is to provide a novel transmission line section having a cylindrical outer conductor and an eccentrically and adjustably positioned inner conductor.

Other objects and advantages will become apparent from the specification taken in connection with the accompanying drawings, wherein,

Fig. 1 is a view in side elevation and partly in section of an electron discharge tube structure adapted to be used in a high frequency transmitting and/ or receiving system wherein the present invention may advantageously be included. y"An electron discharge tube of the indicated type is disclosed and claimed in acopending divisional application filed in the names of the present inventors and bearing Serial N o. 420,771;

Fig. 2 lis a perspective view rof the fine tuning adjustment of the tube of Fig. 1;

Fig. 3 is a longitudinal sectional view of one typ of impedance matching device, or impedance transformer;

Fig. 4 shows a radio transmitting system incorporating the tube of Fig. 1 and the impedance transformer of Fig. 3;

Y Fig. 5 is a view partly in section of a detail of Fig. 4;

Fig. 6 is a sectional View. of the antenna and reflector of Fig. 4;

Fig. 7 is a longitudinal section vof an alternative type of impedance transformer;

Figs. 8, 9 and 10 are cross-sections of Fig. 7 taken along lines 8 8, 9 9 and Ill-I0 respectively;

Fig. 11 is a diagram explanatory of the operation of the device of Fig. 7; and

Fig. 12 is a longitudinal cross-section of a further modification of impedance matching transformer.

In the drawings, Fig. 1 shows an electron discharge tube structure I comprising an indirectly heated cathode 2 having a heater 3, a modulating grid 5 and spaced, cylindrical, resonators or resonating chambers'l, 9, II. These resonators have rigid dished walls I3, I5, I1 and opposed ilexible walls I9, 2|, 23, respectively, the dished walls being centrally apertured and provided with grids. 'Flexible walls' I9 and 2l of resonators 'l and 9 are joined by a' drift tube 25 also having grids at it-s ends opposite the grids of Walls I3 and I5. This tube 25 has a central threaded portion 21 for retaining'a thrust plate 29 thereon. The main body 33 of the tube I carries a flange 35 which has several threaded holes 3l, in this case shown, for illustrative purposes only, as three in number although only two are visible in the showing of Fig. 1. These threadedholes 3l carry thrust screws 39, one end of each of which terminates in a shape suitable for the application of a Wrench for turning the screw, or in a'slot for receiving a screw driver, while the otherL end terminates in a socket adapted to receive the ball headsV of .thrust rods 4l, 43. The screws 39 also have lock nuts for maintaining them in their set position. TheV other end of each of the thrust rods 43 is placed'in a socket in the thrust plate 29 similar tothe sockets in screws 39. The plate 29 has rigidly fastened to it, as by screws 41a resilient cantilever leaf member 49. The

member 43 is fastened to plate 29 YatQone end only, in cantilever fashion. The unfastened end of cantilever 9 is adapted to be moved by the movable stem l Vof a tion of handle 51 results in transmission of thrustv to cantilever s through ball 59, resulting in deflection of the resilient cantilever; 59. Thrust rod- 4| is socketed at one the fastened end of this member,l and Yat the other end in its screw 39.

Fig. 2 shows plate 2Q with rodst and/Sdn their normal operating position. These rodsv are, held in position in the actual device by the opposition to deformation of the rresonating chamber 'l' created largely by atmospheric pressureacting on the evacuated casing 3%; as described below.

HWhile the cantilever tuning'v means has been ries a tube l l4 terminatinginiouter coolingfns 13.,

Mounted on this tube 'HV is another thrust plate l5 carrying thrust screws 'Fll bea-ring against thrust rods 'iS which in turn bear'against iiange 63, the usual lock nuts 8| beingprovided.

Eachy of theresonating chambers l, 9, l-lI has provided means for, supplying or abstractinghigh frequency energy in the form of concentric line terminal posts whose inner conductorsterminate in coupling or pick-up loops 815.

end in the member mearmicrometer arrangement. 53 mounted as by bracket 55 on plate 29. Rota-l In operation, electrons emitted by the cathode 2 forma beam which `may be modulated bysupaplying suitable potentials togrid''.; The electrons are accelerated by the potentialI diierenceibetween cathode 2, usually maintained; at a high negative potential, and'rigid" wall I3; which acts as an accelerating electrode and is `usually grounded; As is well known, thepassing ofthe beam. throughA the rst resonating chamber T, knownA as the buncher effects recurrentchanges invelocity ofthe electrons, ofthe beam. Passage of electronsthrough the drift tube 25 permits the electronsto'bunch, and to give up their energy upon passage through the secondresonator 9, known as the catcheri Output energy cannbe obtained from the resonator 9. However, morder to prevent theabstraction of energy from affecting the frequency characteristics ofresonator il andof resonator l, which may, in someY applications of the device, be coupled to resonator',v the electron beam, now bunched, is allowed to pass through the further resonator I l, and output energy is` obtained.from Vthis resonator, whichlcannot reflect back into4 the other resonators 'i and 9 Y to change their frequency characteristics since it' is coupled tothe other resonators only by the electronbeam. The novel tube of this invention thereby includes a buffer. stage or resonator, as well as the buncher and catcher stages or resonators.

.Asis well known, the frequency of operation of such devices as the present depends onthesize and shape of the resonating chambers; The present invention providesl means for'adjustingv the frequency of-each-of the/resonators. Thus, it is cleary that turning screws 'H will create a-thrust between plate l5 and ilange E3, kwhich Willbe tained by this means.

` chamber, which tends to collapse the flexible wall. This adjustment of screws 'Il' therefore causes deformation of the flexible wall 23, thereby changing the resonating frequency of this resonating chamber Once adjusted, the frequency may bemaintained by use of the lock nuts El to maintain screws 11 in desired position.

Turning screwsY 55 will in like manner create relative thrust between the rigid and flexible walls of resonator 9 and causetuning of this resonator. It will be noted that this tuning cannot affect the tuning of resonator l-I, since no between the rigid andA flexible walls `of thatnresonator by turning screws G5. At most, a slight motion ofthe Wholeresonator H occurs,- due to deformation of flexible Wall 2|v of resonator Si InV the-same manner, the frequency 0f resonator 'l canf-bevadjustedby screws 39; Here again', no effect is produced on either of the otherlresonators. Itis obviousthat the tuningof-each-'of the resonators isindependent of anyl other,- andthe resonatorsmay be adjusted in anyY desired order;

In the case/of resonator 'I there-is further provided the novel ne cantileveradjustment for tuning above described.V y It willbe seen-that turning micrometer handle 51 will createlathrust on resilient cantilever iii through ball' 5e: This thrust is transmitted'to rod il by thecantilever actiony of member-:159- and thence toresonator chamber l. A dual refinement of tuning-isch'- First, there is `the reiine-l ment by use of a micrometer screw insteadofthe ordinary screws Se. Thereis a secondgreflnee ment in tuning by use'of the cantilever arrangement, even over an ordinary rigidA lever, arrangement. AIf anordinary lever were used, pivoted-at f wouldbereduced screws lil', the/motion of rod 4I relative to that of micrometer rod' tby aI factor which is proportional to the ratioof their relative distances from the pivot. The novel method here used-obtains a further reiinement'overl such a pivoted lever arrangement, since thereduction in Adeflectionorod 4l, using the` cantileveriar'- rangementv and` neglecting the` opposing; force created by rod El, isby ar factorroughly'proportionalvto thev square of the ratio of the' relative distances, sincethe cantilevenassumesa roughly parabolic-shape. Furthermore, the effect'ot'the opposition'of rod i to being moved bythe application of force to the endof 'the; cantilever tg'is to further reduce'therelative motion, van'dtoeffe'ct further refinement`4 of tuning. point of View, thisl results in-further curvature of the cantilever spring, makingjfthe deilectionv of rodil proportional to .the appliedlmotionby a factor which is inversely proportional to .even higher powers ofthe distance ratio than thesecond power; It-willbe seen thusV that extremely ne andv sensitive tuning adjustments can. be made, which is essential forv successful operation,

especially in small tubes operating'athighfrethrust is` created .From another The transformer 81 is illustrated as comprising a central sleeve 9| in which are mounted the ends of spaced concentric transmission lines 93, 95 Whose outer conductors are permanently connected to sleeve 9| and whose inner conductors extend radially inwardly of this sleeve 9|. These lines may be open stub lines or terminal posts having their remote ends adapted for connection to other transmission lines or loads. .Two cylindrical end members 91, 99 are carried by or formed in sleeve 9 I. The members 91, 99 are bored to a suitable diameter for receiving a slidable snorting plug carrying a reduced rod |03. The size of the bore in member 99 and the diameter of rod I 03 are suitably chosen to form an eicent concentric transmission line. The remote end of rod |03, shown reduced, is threaded as at |05. Upon this threaded portion is screwed snorting plug |01, which ts snugly but slidably in the bore of member 91 and has an enlarged portion |09 serving as a knobwhereby the distance between the inner faces of plugs |0| and |01 may be varied by turning knob |09, and the entire unit composed of plugs |0I and |01 and rod |03 may be slid back and forth longitudinally within outer members 91, 99 and sleeve 9|, by longitudinal translational motion of knob |09.

Rod |03 slides within a fixed sleeve I I, whose outer diameter is so selected that it bears the same ratio to the inner diameter of sleeve 9| as the diameter of rod |03 does to the bore of members 91, 99. Sleeve I |I is permanently connected to the inner conductorsof transmission lines 93, 95 and is therefore immobile with respect to sleeve 9| and members 91, 99. Sleeve |II tapers down to the size of rod |03 at its end proportions, as shown. Members 91, 99 have a corresponding internal taper. These tapers are s0 chosen as to maintain constant the ratio of the sizes of outer diameter of the inner conductor to that of the inner diameter of the outer conductor, thereby preserving substantially constant characteristic impedance for all sections of this concentric line element. l

The method of operation is as follows: knob |09 is turned until the distance between the inner faces oi shorting plugs |0| and |01 is approximately one-half wave length atthe operating frequency. rlhen the whole inner portion, comprising rod |03 and plugs IOI and |01, is slid back and forth until the proper match is obtained. At the optimum point, the device connected to line 93 in parallel with the short circuited stub line to the left 0f the connecting point of line 93 is matched, over the section of line between the connecting point of 93 and that of 95, to the device connected to line 95 in parallel with the short circuited stub line to the right of the connecintg point of 95.

The impedance transformer of Fig. 3 will match, with certain limitations, a device o-f any impedance value to another device of any impedance value connected therethrough. It lis perfectly symmetrical in action; that is, when a lower impedance Value is to be matched to a higher impedance value, the device having either one may be connected to either terminal of the impedance transformer.

Fig. 4 shows an arrangement using the above impedance transformer in which resonator 9 is coupled back to resonator 1, as by transmission line I I2, thereby causing tube to generate oscillations. The output of tube I is taken from buffer resonator I I by means of transmission line II3 to preserve stability of oscillation, and is connected,

by means of phase adjuster I 1, impedance trans'- former 81and transmission line |I5, to a load shown as antenna 89. This figure shows an electron discharge tube of the type described above, coupled to an antenna 89 by means of transmission lines II3 and II5, phase adjuster |I1 and impedance transformer 81. In tube I, resonator 9 is shown coupled back to resonator 1 by line I I 2, to provide oscillations. Transformer 81 and phase adjuster` 1, which is of the sliding joint type further described below, are shown as mounted on a base I I9 by means of bracket I 2| which holds the impedance transformer 81 and the xed part 93 of the phase adjuster II1. The movable part ||4 of the phase adjuster I|1 is connected to screw |23 by a member |25. The screw |23 is threaded into the bracket |2| so that rotation of the screw 23 will produce relative motion between the two parts of the phase adjuster I I1. Transmission line I I3 is connected directly tothe buffer stage output of tube I `and is connected to the input of impedance`transformer 81 by means of the sliding joint of phase adjuster |I1 more fully described in connection with Fig. 5. As an illustrative example, let us take the output impedance of the tube I to be 30 ohms. Then, transmission line I|3 may be modified by the variable section of phase adjuster |I1 to' be a, half-wave (or multiple of a half-wave) line, so that thek impedance at the input of the transformer, looking back at the tube, will also be 30 ohms. The transformer is then adjusted to transform this value of impedance to some value such .as '72 ohms,jand then a 'Z2-ohm line (i. e. line I I5)L is connected to the output of the transformer. This 'l2-ohm line I I5 is then shown connected to a :S6-ohm quarterwave antenna 89 by means of a matching section |33 shown more in detail in Fig.

The sliding joint phase adjuster of Fig. 5 has a lixed part 93, with inner conductor I 3 I, and a sliding part I I4, with inner conductor |29, and relatively movable by means of screw |23. With the ordinary type of sliding joint it is almost impossible to avoid Iwave reflection because of the discontinuities involved. The joint of Fig. 5 is designed to avoid these reflections. The inner conductor |29, which slides over the inner conductor I3I, is extended one-quarter wave length beyond its outer conductor II4. Furthermore, the relative dimensions of conductors |29 and 93 are so chosen,

that the section of line between points P and Q has a characteristic impedance which is the geometric mean of the impedances of each-of lines 93 and II4. Methods for calculating the dimensions of transmission lines to obtaina given impedance are taught in standard textbooks, such as Radio Engineering, by F. E. Terman (2d edition, p. 698). In this Way, the extended portion of conductor |29 forms with the outer conductor 93 a quarter-wave matching line which causes lines 93 and II4 to be matched perfectly without reflections occuring.

Fig. 6 shows a tapered line section |33 for matching the line II5 to the quarter-wave antenna 89. In the example used above, this line section |33 would have to match the 'l2-ohm line II5 to the 36-ohm antenna 89. This section |33 is one-half wave length long, and has an exponential variation of impedance with length. Thereforagthe diameter of theinner conductor varies as an exponential function of an exponential function of the distance along the line` section.

The variation of inner-diameter shown in Fig. 6 is that needed for matching in the illustrative anode-7.a

example .useda For matching -othervalue'soiixnpedancethe prole of the inner conductor! may bef-concave', instead of `convert as shown', or'may heb-oth` concave and convex With a poi-etici in-r fiection, dependingi on theparticulair valuesof impedanceto be matched.

'The' explanation of the-l operation of thisnline section to. prevent" reflections andstanding waves is'similar'to that'v of. the usual quarter Wave line section. InI such a: quarter wavesectiom a trave elingl Wave will seti un a reilection at the' beginningv of the-section. Theunreflected portion will travel quarter-Wave length furtherr and set `up a second reected vvaveat thev discontinuity at the section. This ksecond. reflected'vlave Y' the end of W-ill travel back quarter-wave lengthand Will then be out' of' phase with hence thev two reilect'ed waves* will` neutralize', provided4 the proper amplitude relations are:ob served.' This is insured by having the character-- istic impedance'of the. quarter-Wave length section equal the geometricme'an' of the two in1- pedances to be matched.

The present half-Wave length sectionv operates in a similarmanner; that is, the reflectedwave at'the end |23 ofthehalf-Wave length section |33is' used to neutralize the Wave setup. ati the beginning |39 of the section 33. One important difference exists here: in the case ofy the ordinary quarterwave lengtliisection, the change in impedance at'the'v points of discontinuity is in the same directionl at both'. en'dg of' the line section; that is", both-have increasing impedance values or botnfhave decreasing impedance values. In the case of'the present section. 33, the types of discontinuity are opposite; that is, thereisa break' from constant" impedance to: varying im the'r rstreiie'cted Wave and pedance at mi, and then a' sec'ondlbreak' from varying impedance to constant impedance at |28. This introduces an additional?.v 180 degrees'phase shift between the two reflected Waves. Hence, for neutralization, the line must be half-Wave length (or 180 electrical degrees) long, softhat adding up the phase shifts caused by the" direct wavetravel time, the reiiection, and the reflected Wave travel rtime will result inzphase' opposition; The proper amplitude' relations" are observedby having an exponential variation ofim'- pedancealong'the section |33. Since impedance variesfasth'elogarithm of the ratio ofioiuter"con-V ductor diameter to' inner conductor diameter, and since the outer conductor |331 is constant` inrdiameter, this necessitates a doublyu exponential Variation of the diametericftheinner conductor V|3121' v Figs. 7- to 10 show an alternativeforrn of i1n pedanceltransformer'Whichwilloperate to transforxn or matchf the impedance of a fixed impe'.- dance element into anydesired impedance value. It mayi serve' to match a device' having an'arbitrary impedance value with that of a particular concentric transmission: line. This matching transformer' has an` inner conductoriSS which has an intermediate. onset portion i3?` at'. least three-quartersci a Wave length long. Fixed to the. inner conductorv |35. are two sleeveportions |39,. |4| xedly joined to theinner conductor byinsulati'ngimember's |43. Slidably, mounted-Within sleeve |39 and outside of conductor |351 is va conducting sleeve i'rnaintained elec trically'separate from conductor |35l byinsulating member HW.'Y Theinsulating member |51 slides on conductor |35 and is iiXed to sleeve I. Obviously, member IM couldijust a's-vvellbefxed to? conductor |35 andi sliderv invsleeve-Iv 45. Y- A-sleeve pacitanceand.'therefore to |49? isi similarly arrange'd. 'Within sleeve,` MI.f Sleeves |45fand. i'fhave thin-Walled sectionsf |514 and will extending away.' frorn the center of: the device: These? thinewalled, sections are exactly onequarter'wave length long andso dimensioned that. anale-gunste: thedevice of Fig;r 5, the thinwalled sections' act as quarter-Wave matching 1ines=between=the terminalline and the line cornposedof sleeve Ilia (or SL19) and conductor' |35, the'chara'cteristic impedance of these matching line'sibeingequalto. the. geometric mean of the impedances'r of thelines immediately connected thereby Each of these sleeves |45 and' HiB has a= tapered-portion |51 which may be slotted axially. FixedlyI attachedl to sleevesl-4 and m9,' are threaded.. ring-s` |5'.. Theseengagewvvith clamping rings' `l 552 havinga taperedk portion mat'- ing'` with tapered portion 52', I-`whereby, upon threading-clamping ring len ring l; the-taperedportion.. l5 if isi' clamped against sleeve M5 or M9, servingct'o keep rings Saandv M5, orgie-i and M9, in theiry adjustedpositio'ns. SleevesA M25 and |49 are joined, by an eccentric yokev mernber |511 Sleeves lll'andjlmay have flanged ends'asfat m91 Yoke |5iisprovid'ed WiththreadM edV portions ll cooperate withfrings it to prevent-sleeves |655k andi |69 fromany relative axialmotiom While'leaving. yoke ilfree tor tate.Y rIhe'por-tio'n of yoke li'which-cooperates with offset portion. |31 orV the inner conductor is exactlyfonequarterfWave length long.

Inner conductor.'A |35' and Isleeve |39 (or ISH) may have' any relative: sizes', but arefpreferably so proportioned as tof constitute one of-the usual concentric transmission line sizes.V The portion of the; transmission; line: formed by the offset inner conductor i3? and sleeve |45 (or |59) is proportioned t'o--lo'zwathe same impedance asthe Y,

porti-on of lin'e'.- constituted` by.- innerconductor |35 and outer conductor ist: (or Ml), so that no losses or.' reflections.. Will be encountered at the junctions of offset andregular portions; effect oioffsettingfthe inner conductor of a concentric transmission line is to increase its cadecrease its character-v istie impedance' TheY effect of decreasing. the diameter ofthe inner conductor oi" a concentric transmissionline is to increase its characteristic impedance'l Hence', the diameterr of the offset portion' ofthelinner conductor is reducedby the amount necessary; to compensate for the decreasedcharacteristic impedance caused by oil- Y setting,V leavingithenet impedance the same.

The diameter of theeccentric openingin yoke |51r is adjusted so thatat the most eccentric position of". the rotation of yoke E, the yoke just touchesthe offset' innerf conductor I3?, as shown in Fig.` 9,' and at` theV other extrerneof rotation the inner conductor |31 is concentricWith-thc sleeve opening, asshovvnl in Fig. 8. For other'deg-rees` ofA rotation there will be spacings' of inner 'conductor l'with respect toy yo-ke'ril varyingY l front-thatrshown in'Fig.y 9 to that shown in Fig. S.

Endcaps andV adapters |65 for connectingv the device 'toi standardl concentric transmissionlines are.' provided, usingl the proportional taper explained; in connection with Fig. 3.

The operation of the device of Fig: 7 can best be explained'on the basis ofthe diagramof Fig. 11; Thisilguren shows', on animpedance-diagrani WhoseI coordinate aXes represent resistance and reactan, the constant-coordinate lines of aibipolar coordinating system'having poles such asfZo.v Onlyf the right half of this diagram is shown, the left. half. beinga mirror image oflthe The 9 right. 'Ihese constant-coordinate lines form two families of circles, one family with centers on the X-axis (axis of reactance) and passing through both poles and the other family having centers on the R-axis (axis of resistance) such that each circle of one family crosses every circle of the other family at right angles. This system, therefore, forms an orthogonal curvilinear coordinate system known as the bipolarcoordinate system. It can be shown that, if the poles of such a system are chosen to be th'e points representing the characteristic impedance of a transmission line, and if an arbitrary impedance value is selected, such as represented by point Z on Fig. 11, and connected to varying lengths of the transmission line, `then the net impedance, looking from the remote end of the transmission line to impedance Z, is represented by points moving along the constant-coordinate circle ZRiRz passing through Z. This impedance locus makes one complete rotation around Zu, back to Z, for each half wave-length of line added. Thus we see that, in order to tune impedance Z to resonance, enough line must be added to carry the net impedance to point R1. This would give a high resistance resonance condition. If more line is added, we finally reach a low resistance resonance point R2.

The above theory is used in the operation of the device of Fig. 7. Let us assume, for illustrative purposes, that sleeve |39 and conductor |35 make up a '12 ohm line. It is desired to match a '12 ohm line to any arbitrary value of impedance, not necessarily purely resistive.Y The 72 ohm line is connected to the left end of the impedance transformer, which it matches since it has been assumed that this left end constitutes a 72 ohm line. The element having any arbitrary impedance value is connected to the right end of the device. The length of transmission line between the element of arbitrary impedance and the beginning of eccentric sleeve |51 is then adjusted by sliding sleeve |49 within sleeve |4| until the value of arbitrary impedance plus that of the line, looked at from the beginning of the eccentric sleeve |51, exhibits minimum resistive impedance. This corresponds to transforming the point Z (Fig. 1l) to point R2 by adding a length of line corresponding to th'e heavy arc ZRiRz. If we look to the left from the left edge of the eccentric-sleeve |51, there is also exhibited a pure resistance, since everything connected to the left end of the transformer is matched. This resistance however, is not R2 but Zu. There-remains the step of matching two purely resistive impedances of diiferent values. 'I'h'is is done by rotating the eccentric sleeve |51 to the proper position, which will be that at which the quarter wave length line |51 exhibits a resistive impedance R3 equals \/Rz.Zo, i. e., the geo-metric mean of the two impedances to be matched.

Since the sleeve |51 constitutes a quarterwave length line, its impedance will always be resistive. Rotating the sleeve will vary the position of the inner conductor |31 relative to the outer conductor (sleeve |51) from that shown in Fig. 8, which has maximum resistance, to that shown in Fig. 9, which has Zero resistance. If the eccentric sleeve'cpening is properly proportioned relative to the diameter of offset inner conductor |31, the quarter wave length line can exhibit any resistance from Zero to a value at least as large as Zo, so that by properly positioning the sleeve, the required-resistance, such as l0 R3 (Fig. 11) can easily be obtained, providing substantially perfect matching.

Fig. 12 shows another embodiment of impedance transformer which also can match .the impedance of any impedance element to th'at of any other impedance element. This embodiment comprises a concentric line device having an outer cylindrical conductor |91 in which is fastened a perpendicular sleeve section |69 of equal diameter. Supported within conductor |51 as by insulator |1| is a concentric inner conductor |13 which also has a perpendicular section |15 of equal size which is concentric with section |59. A reducing end cap having tapered portion |11 similar to |95 in Fig. '1 is provided for coupling this device to a standard line or other impedance. The diameter of the concentric line section forming the impedance transformer is made larger than the line to which it may be coupled'in order to increase eiiiciency of operation. y

Inner sleeve |89 ends one quarter of a wave length within the end of sleeve |85. The portion of sleeve |85 not opposite sleeve |89 (that is, the last quarter wave length) has a thickened wall, formed in this instance by inserting sleeve |9| permanently fastened to sleeve |85. The dimensions of conductors |91, |13, I 9|, |85 and |89 are so ch'osen `that the characteristic impedance of the Lili- |13 section of line is equal to the geometric mean of the vcharacteristic impedances of the |51-|13 and |85| 89 sections, thereby avoidingreflectionsvat the sliding joint, as discussed above.

Accordingly, an impedance matching transformer has thus of arbitrary impedance values may be matched by adjustment of the length of a section of concentric transmission line connected in cascade with one of the arbitrary impedance values and by the subsequent adjustment of the length of a short-circuited section of concentric transmission line connected in parallel with the cascadeconnected transmission line section.l It is understood that the order of these adjustments is immaterial. f

The theory and method of operation of the V'device of Fig. 12 may be explained on the basis of a diagram similar to Fig. 1l, but wherein the coordinate axes represent susceptance B and conductance G rather than reactance X and resistance R so that the diagram represents admittance Y rather than impedance Z. Such an ad-v mittance diagram coordinate system poles would be the would have the same bipolar as shown in Fig. 11, butthe characteristic admittance instead of characteristic impedanceZo. VFor simplicity, Fig. 11 will be used again, it being understood that, wherever the symbol Y is used, the

admittance diagram is meant.

Now, if it is desired to match two loads having admittances Y1 and Y2, respectively, it will be been provided whereby any` pair' Such added susceptance is Yferent embodiments of i121 necessary .to match :both fthe fsuscentanccs and conductances of these'loads. YBySgrafdually sadd- V ing transmission sline .having .admittance sin to 4Vsusceptance, we can match uthe :admittances 'iYl and and therefore theimpedances, perfectly. obtained by .varying thelengthiof Vstubline .I 69.-.- I 15,'-by1moving plunger :|81 in Ior out to .add :the proper amount of susceptance v.in 4parallel lwith the line .section 'ljBL-Jll'l-S. lfthe admittance Ya-shouldhetvholly to l:the right or left of the circle traveled byYi,

thentit is merely necessary to interchangeYl and Y2; .that is, Y2 would then be connected to the tightend ofithedevice vof Fig. =12.

'From the above analysis, itis evident that to `use' the 4device o'fllig. 12, 'itis:merelyinecessaryto connect Loneirnpeda'nce `element kat Teach then vary-.thelength of line at the sliding lio-int :until the .conductancesbecome matchedgand thenvary the `Ashorlting lplug =until the -susceptances .are matched. Then the impedance values/of the two impedance .elements will 'be matched.

As .many rchanges could be'fmade in v`the above constructions :and many apparently widely ldifthis invention `:could be made without departing from :the scope thereof, it `is intended Ythat all matter `conta-ined in the above `description orshown -in the accompanying drawings shall l-be interpreted as illustrative and not in a 'limitingsense "What'is claimed is:

1. A transformer device for matching `the admittances of any two` circuit elementscorn-aris-V ing adjustable `meansfor converting the conductancefof `one'of `said elements to a rvalue equal '-to that `of :said other element, land independent Aadjustable Arneansffor adding substantially pure susceptance 'to sa'id vconverted conductance to fully match said Vtwo admittances.

#2. VJ'Apparatus for matching twocircuit-elements having any admittance `Vvalues Vcomprising ja sectionof-:transmissionline o'f the-coaxial conductor type xadapted for :connection between said circuit elements, -means Alion-varying the length of said line'section for making the conductance offene cfsaidicircuit elements equal to the conductance of theother circuit element, and ffurther means for .adding .substantially =pure suseeptance to one of fsaid :circuit elements until 'both circuit yelements have fthe same values-of susceptance. Y

' 3. An impedance transformer for transformingV an arbitrary yimpedance value to fanotherjarbitrary yalue, comprising an adjustable 'length section of concentric transmission 'line 'adapted to `be connected Ain cascade to said arbitralyfimpedance value, and an adjustable 'length ofshort circuited .section .of concentric A transmissiondine connected 1in shunt `,to said first sectionintermediate the ends thereof, whereby ,said .other arbitrary impedance value .may fbe .obtained `.by v

adjustment of the lengths of said two sections.

4. An impedance transformer for matching the impedances of two -circuit elements having` any impedance values, comprising an adjustable length section of 'transmission line adapted to loe connected in cascadebetween .said elements, fand an adjustable length section of .transmission lin-e connected .in shunt Atosaid .rst,s ectdon intermediate the ends thereof, whereby saidl impedanccs may7 be Amatched-.ley adjustment of the 4lengths of said twosections. 1

5. rin impedance ymatching transformer com'- pnising asection of hollow transmission line havinst la vfixed unitaryinner conductor, means cooperating witha section of said inner conductor il. An.impedancetransformerfor matchingany y two .impedances comprising means yincluding an adjustable length section .-of concentric transmission `line connected fin .cascade with one of said limpedances .for converting the conductan ce of .said .one impedance .toga value vequal to that of .said ,.other impedance, and ,means including an adjustable length .short-circuited section of concentric vtransmission line `con-necteri in parallel with said rst section for adding suscepta-nce to said .converted impedance to 'fullymatch saidV twoimnedances. f

8. .An .impedance matching transformer comprising .a .transmission Yline section of the coaxial conductor .type .and of .substantially invariant over-all 'length having an l.outerYc ondilctor :made up ,of an .axially adjustable :central `rsection ,havinga portionof-eccentricfbore and-relativelyyfi-xed end sections for telescopingly lreceiving isaid central section .upon .adjustment jof said central section, .and an inner .conductor cf `iixed :length :extendingfbetweenandxed tosaidfend sections.Y

9. Apparatus for .transforming any :arbitrary impedance value .to another vvimpedance -value comprising a -xed lengthofvcoaxial type tra-ns-` mssion -line .having input and output terminal portions and :adapted .to .be connectedsat one of said portions .toa circuitelemerrt havingsaidgarbitrialjyimnedance value, adjustable transmission line means .having variable characteristic impedanGe coupled ,in .Cascade .between said 'termina-l portions and .mutually zcooperable means ateach Of ...Said .terminal portions for simultaneously equally and .Qinositely .varying the length offline fromy one of said terminal'portions to vsaidvariable characteristic :impedance means and the length of Y.line from .the ,other of .said terminal portions to .said variable :characteristic -impedance means.

1 0. A n Aimpedance `matching transformer for matching la transmission line to any load, -comprising means, includingV an adjustable ,section of transmission line having a telescopi-ng .cylindrical louter conductor and a .concentric inner conductor vwith Van off-set .eccentric portion, .for converting the impedance of said load to a Pure resistance, and further means, including a quarter centric :to .saidtend pieces, and a :sliding :member 1 variable impedance comprising a quarter wave section of conductor having a bore eccentric to and surrounding said olf-set eccentric portion and rotatably xed between a pair of outer conductor sections slidably engaging said end pieces, whereby, by translation of said sliding member, the reactance of one concentric transmission line, connected to one of said end pieces and said inner conductor, may be matched to that of second concentric transmission line, connected to the other of said end pieces and said inner conductor, and by rotation of said eccentric quarter wave lsection the resistances of said reactance matched line may also be matched.

12. An impedance transformer as in claim 11 wherein the diameter of said off-set portion of said inner conductor is reduced by the amount necessary to match the impedance of the line formed by said concentric inner conductor and said outer conductor section to the impedance of the line formed by said eccentric inner conductor and said outer conductor section.

13. An impedance transformer as in claim 11 further including means for preventing reflections at said sliding joints, comprising a changed inner diameter of the inner one of said slidingly engaged conductors for la quarter wavelength from said joint, said changed diameter being of the proper amount to make the characteristic impedance of the line section comprising said changed diameter of a value substantially equal to the geometric mean ofthe characteristic impedances of the neighboring sections of concentric transmission line.

14. An adjustable concentric transmission line comprising a iirst section having an inner conductor and a concentric outer conductor, a second section having ,an outer conductor adapted to slidingly engage the outer conductor of said iirst section, and having an inner conductor adapted to slidingly engage the inner conductor of said iirst section, one ofV said conductors of said second section extending a Vdistance equal to a multiple including unityof a quarter of a `wave length of the operating frequency beyond the other of said conductors of said second section, whereby a portion of said line is formed by one conductor from each of said sections, the dimensions of said inner and outer conductors being so chosen that the characteristic impedance of said portion has a value equal to the geometric mean of the characteristic impedances of said two sections.

15. The transmission line dened in claim 14, wherein the inner conductor of said second section extends said distance beyond the outer conductor of said second Sectio 16. An adjustable concentric transmission line comprising an inner conductor, a first sleeve surrounding said inner conductor, a second sleeve surrounding said inner conductor and slidingly iitting said first sleeve, the inner diameter of the end portion of the inner of said sleeves being different from the inner diameter of the adjacent portion of said inner sleeve for a iixed distance of substantially one quarter wave length of the operating frequency, the inner diameters of said sleeves and the outerdiameter of said inner conductor being so chosen that the characteristic impedance of the section of concentric transmission line which includes said end portion has a value equal to the geometric mean of the values of the characteristic impedances formed by said two sleeves and said inner conductor, whereby no 'wave reflections are obtained at said sliding joint.

17. A transmission line comprising e. hollow tubular outer conductor, a rst section of inner conductor substantially concentrically mounted within said outer conductor, a seco-nd section of inner conductor comprising a continuation of said first section but eccentric to said outer conductor, and a rotatable portion of said o-uter conductor having a bore eccentric to the remainder of said outer conductor, said bore being disposed about said eccentric inner conductor section.

18. An impedance matching transmission line device comprising a hollow outer conductor made up of a central portion and telescoping tubes providing end portions adjustable in length, a substantially concentric inner conductor having an intermediate section eccentric with saidouter conductor, and a rotatable section of said central portion of said outer conductor having a bore eccentric to said outer conductor and disposed about said eccentric inner conductor portion.

19. A reflection eliminating transmission line joint comprising two sections of transmission line of the coaxial conductor type, means interconnecting said sections for relative axial adjustment, and means comprising an impedance matching section in said line between said'two sections, said matching section having a ratio of diameters of inner and outer conductors different from that of said other two sections, and said matching section having a xed axiallength substantially equal to a multiple including unity of a quarter of a wavelength of the operating frequency, which xed length is maintained 'during all positions of relative adjustment of said two sections.

20. A reflection eliminating transmission line joint comprising two sections of transmission line of the coaxial conductor type, means telescopically interconnecting the outer conductors of said sections for relative axial adjustment, and means providing an'impedance matching section in said line between said two sections, and having a I ratio of diameters of inner and outer conductors different from that of said other two sections, said matching section comprising the terminal portion of one conductor of one of said two sections extended coextensive with the corresponding other conductor of the other of said two sections, and said terminal portion having a xed axial length of one-quarter of the wavelength at operating frequency, or a multiple thereof, which fixed length is maintained during all positions of relative adjustment of said outer conductors.

21. The transmission line joint dened in claim 20, wherein said terminal portion is an Vextension of one'of said outer conductors.

22. The transmission line joint defined in claim 20, wherein said two sections have substantially common inner conductor means, and said ter minal portion is an extension of one of said outer conductors.

23. The transmission line joint defined in claim 20, wherein the inner conductors of said two sections are slidably engaged, and said terminal portion is an extension of one of said inner conductors beyond its associated outer conductor.

24. The transmision line joint dei-ined in claim 20, wherein the inner conductors of said two sections are slidably engaged, and said terminal por# tion is an extension of one o said outer conductors. WILLIAM W. HANSEN. JOHN R. WOODYARD.