US2266500A

US2266500A - Energy transfer circuits

Info

Publication number: US2266500A
Application number: US287016A
Authority: US
Inventors: Nils E Lindenblad
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1939-07-28
Filing date: 1939-07-28
Publication date: 1941-12-16
Anticipated expiration: 1958-12-16
Also published as: GB542780A

Description

Dec. 16, 1941'. N. a. LINDENB AD 2,266,500

ENERGY TRANSFER CIRCUITS Filed July 28, 1959 2 Sheets-Sheet 1' a 2 TOGR/DB/AS L 29 7'0 F/LAMEN T #54 TING SUPPL Y 30 3.5 32 DRIVER I INVENTOk l 3/ N/LS .ulvosmmo 34 v BY 7 A TTORNEY.

Patented Dec. 16, 1941 Nils E. Lindenbla rPort .JeifersonQN. Y assignor to Radio Corporation of America, a corporation of Delaware Application lnly'2 8, 1939, =S'eri'a'l No. 287,016 s roiaims. retest-26) This invention relates to energy transfer circuits, and particularly to concentric transmission line circuits having hollow inner conductors for accommodating connections to suitable translation circuits.

One of the objects of the present invention is to provide a concentric transmission line and a circuit therefor by means of which a pushpull action can be translated into push-"push action.

Another object of the invention is to provide a con'centric transmission line having a hollow inner conductor wherein the length of the coupling lead between the transmission line and a translation circuit outside of the field or the'com centric line is brought to anabsolute minimum. Another object ofthe present invention is to provide an'oscillation generator having a, single quarter wavelength concentric :line controlling a pair of electron discharge devices connected electrically in push-pull'relation'. A further object of the invention'is to 1 pmvide a circuit by means of which the two branches of a source ofpush-pulloscillations may be "equally loaded by a single concentric trans:

mission line. c 1

A still further objectis toi provid a circuit by means of which two branches of a balanced or symmetrical translation. device ;or, load may be equally loaded by asingle resonancespace or chamber. I 1 In brief, the present invention may be said to be based on the appreciation of the fact that the interior of the inner conductor of a concentric line contains no; electromagnetic field resulting 'from the currents betweenthe inner and outer conductors of the concentric line, and may be considered asbeing divorced from the concentric line in the sameman'ner as 'the'spa'c'e exterior to the outer conductor of the concentric line is divorced from the action within the con--v centric line. Due to the fact that there are opposite instantaneouspolarities onvth'e interior surface of the outer conductor and on the ex: terior-surface of the inne'r conductorand the fact that the interior ofjtheinner conductorarid the exterior'of theouterfconducto'r have no electromagnetic field, I make use of these conditions in the concentric line to obtain, from those surfaces of the inner and outer conductors which face each other potentials of opposite polarities. For deriving these opposite instantaneous polari-ties, a connection is made fromjthe ne surface 'of the outer conductor throughan' apertime threofl and another connection ismade from the exterior surface-0f the-inner conductor through an apertu-re in'the outerconductor to the'space outside the concentric line. In another em'bodimem I make use "(if the same principle 'to 'obtain currents of opposite instantaneous polarities frame hollow resonant chamber whosecbnfronting surfaces have opposite instantaneous potentials. This last case, of course, involves no inner conductor, such as is -ernplo'yed in a concentric line, and represents "the simplest 'way of der iving potentials of opposite instantaneous polarities "from af tuned circuit. j O'th'er"dialects and "features will appear in the followingdetailed description of the invention which is accoinpanied by drawings, wherein: Figs. 1 and '2 sho'w oscillation generation 'system's mploying a single quarter wavelength tuned iconcentric line'for controlling a pair of vacuum tubes in electrical push-pull relation;

Fig: 3 shows the 'man'n'er in which 'a balanced push pull circuit can be: coupled to a single concentric transmission line, and vice versa, without (the introduction of impedance irregularities; Eig; 321 shows, in a manner similar to that of Fig'. 3, how a pair or balanced push-pull circni't'scan be coupled to each other by way "of a 'singl'e'concentric transmission line acting as aniimpedance transformer; t Fig. 4' shows an oscillation generation system wherein the'va'cuum tube is contained within the'inte'rior of the inner conductor of the timed concentric .line resonator, the connections between the electrodes of which and the resonator having a -minimum of reactance;

- Fig. 4a illustrates the equivalent electrical circuit diagram 'of Fig. 4; r

"Fig. 4b illustrates *a cross :section of an oscill'atorr'syste'm o'f a'type similar to Fig, 4, showing the 'ap'refer'red mechanical achieving a minimum of 'reactance in the connecting .leads between the vacuum tube and the tuned concentric line; and 5 'shows a modification 'of the invention inwhich potentials" of opposite instantaneous polarity are obtained from a hollow resonant chamber. V I -R'eierring to Fig. 'ly-there is shown a concentric resonant*line comprising an inner conductor 1 and an outer surrounding'conductor '2 connected to the inner "conductor I at one of its ends by means of' endplate '3. inner conductor I is made tofbe electrica-lly on c-quarter oi a wavelength long at A the desired operating triednen 5y and is the c' fid tdf gyf f t idrfit mimics-mesa a portion of its interior. This arrangement for is connected to the inner surface of the outer conductor 2 by means of a connection 5 extending within the interior of the inner conductor I. The grid of vacuum tube 8 is connected tothe outer surface of the inner conductor I by means of a connection 5 which extends through an aperture in the outer conductor 2 to the interior of the line. Both connections 5 and 6 connect to the conductors I and 2 at points substantially the same distance from the end plate 3 in order that the loops formed thereby may encircle substantially the same amount of flux within the concentric line in order to derive therefrom equal loading for the grids of the vacuum tubes. Due to the fact that there is a potential difference between the outer surface of inner conductor I and the inner surface of outer conductor 2, and because lead 5 enters the space between the concentric conductors in one direction of potential gradient while conductor 6 enters the space between conductors I and 2 from an opposite direction of that same potentialgradient, there will be produced on leads 5 and 6 equal potentials of opposite instantaneous polarities. A parallel tuned output circuit 9 is shown connected between the anodes of the vacuum tubes 1 and 8 to the electrical mid point of which there may be applied a suitable positive polarizing poten.. tial for these anodes. The exterior of the con-v centric line I, 2 is shown by-passed to ground through a condenser III in order that suitable grid bias may be supplied through the choke coil II to the grids via the concentric line. The condenser I is of course strictly not a necessary item since all surfaces exterior to the field of the resonant line are intrinsically at zero potential. It may, however, be well to include this condenser. since it helps keep the line from becoming ex-. ternally energized from external stray. fields. This grounding will be more effective if several condensers are connected at distributed points along the exterior surface of the exterior conductor. It will be noted that the quarter wavelength concentric line of Fig. 1 illustrates one advantageous method of controlling a push-pull oscillator by means of a tuned concentric line.

Fig. 2 is similar to Fig. 1, except that the grids of vacuum tubes 1 and 8 are capacitively coupled to the concentric line I, 2 by means of condensers I2 and I3, instead of the direct coupling shown in Fig. l. The exterior surface of the concentric line of Fig. 2 is here shown directly connectedto ground since the condensers I2 and I3 now isolate the grids 5 and 6 from theconductors of the concentric line. Bias for the grids of vacuum tubes I and 8 is obtained by means ofa choke coil II connected between leads 5 and ,6. From the mid point of the choke coil a connection extends to a suitable source of grid bias.

Fig. 3 illustrates a method of connecting a suitable load circuit, here illustrated as a quarter wave radiator I5, to a balanced push-pull source of oscillations such as a transmitter I6,shown conventionally in box form. The radiator I5 is integral with and forms part of the inner conductor of a concentric transmission line having an outer conductor I! connected thereto by means of an end plate I8 at a point removed from the effective radiating portion. The push-pull transmitter is coupled to the single concentric line I I and to radiator I5 by means of a balanced circuit composed of a pair of transmission lines I9 and 20, the inner conductors of which connect to the single transmission line in a manner similar to that shown in Figs. 1 and 2. It will be seen that the inner conductor of concentric line I9 is connected to the inner surface of outer conductor I'I, while the inner conductor of concentric line is connected to the outer surface of inner conductor I5 at points equally spaced from the end plate I8. The inner conductor of concentricline I9 is disposed within the interior of the inner conductor I5. In effect, the quarter wavelength radiator I5 at the upper end of line I! is anunbalanced circuit which is coupled to the balanced circuit I9, 20. It is preferred that the points of connection of the inner conductors of the concentric transmission lines I9 and 29 to the conductors I1 and I5 be spaced one-quarter of a wavelength from the end plate I8 in order that such points of connection be points of high impedance to currents tending to flow to the end plate I8. Between the conductors I5 and I! the instantaneous directions of the currents are illustrated by means of the arrows on the conductors of lines I9, 20, I5 and I1. It should be noted that the currents on the inner conductors of transmission lines I9 and 29 are in opposite directions, thus giving a push-pull effect, although from an impedance standpoint both transmission lines I9 and 20' are in parallel relation. It should also be noted that the current on the outer surface of conductor I5,becomes the, shell current of the inner conductor of transmission line I9,

and also becomes the center conductor current of the transmission line I120. Because of the quarter Wavelength spacing to the end plate I8, current cannot flow on the outer surface of transmission line I5 .below the aperture through which the inner conductor of line I9 extends, nor below the junctionpoint oflthe conductor I5 with the inner conductor of transmission line 20. Similarly, the central conductor current of transmission line I9 and outer shell current of transmission line 29 become the current on the inner surface of conductor II, this current also being prevented from flowing to the end plate I8 because of the quarter wavelength spacing shown in the drawings. The effective radiating portion of conductor I5 is one-quarter wavelength, as measured from the open end to the immediately adjacent end of the conductor I'I. Both the radiator I5 and the concentric .line comprising conductors I1 and I5 each have an impedance equal to Z, while the impedances of each of the transmission lines I9 and 20 are 22. Since the transmission lines I9 and 20 are electrically in parallel, the combined effect of the impedances 'of I9 and 20 is equal to Z, thus introducing no impedance irregularities at the junction points between the transmission'lines I9 and 20 and the single concentric line I1, I5. It will be obvious that the lower portionof line H between end plate I8 and a point one-quarter wavelength (M4) from this end plate is, in effect, a concentric line resonator containing standing waves, while that portion of line II above the concentric line resonator contains traveling waves, since the load I5 is matched to the line H to form a non-reflective termination therefor.

Fig. 3a shows "a combination of an arrangementshown in Fig. :3 and that illustrated in Fig. of myicopending application Serial No. 183,571, filed January .6, 1938. In Fig.:5'ofmy copending application supra there is "shown an arrangement for connecting a single transmission line of impedance Z in push-:pull relation to a pair of branched transmission lines ieach of them an impedanc'eZ/Z. In this last case, the branched lines are in series with respect to the single transmission line, and no impedance irregularities are introduo'edbecauseof the provisionof a quarter wavelength sleeve surroundingthe single transmissionline and connected to the outer conductorsof both ithe Isingle transmission line and the branch transmission lines. Fig. 3a of the presentsapplica'tion shows the two branch transmission lines each labeled Z/2 Fin series relation with respect to a single main feeder Z, the latter in turn 'being fed by two othertransmission lines each having an impedance 2Z inparallel to each other and extending to a push-pull transmitter I6. The two transmission lines 2Z, ZZ are in push-pull relation to each other although in parallel with respect to the main transmission line Z. The quarter Wavelength sleeve 2| which surrounds the single concentric transmission line Z at its upper extremity prevents unbalance between the branch lines 2/2 and the main transmission line vZ, enabling the free end of the transmission line-Z to-assume the potentials required for balancing the branch lines with respect to each other. The instantaneous currents in the transmission lines'are illustrated by the arrow marks. Since the letter Z represents the impedance of the lines, it will be seen that Fig. 3a shows one method of connecting two transmission lines each of impedance 2Z to two branch lines each of impedance Z/-2, thus effecting an impedance transformation of "4:1, and without introducing impedance irregularities.

Fig. 4 shows aresonant'concentric line having aninner hollow conductor 1 and a surrounding conductor 2 suitably coupled together to form a tuned frequency stabilizing circuit for the vacuum tube oscillator T located within the interior of inner conductor l'. 'The conductors l and '2 are connected together at one end by metallic end plate 3 which is grounded for radio frequency energy, and capacitively coupled together at the other end by an adjustable metallic plate 25 whose position determines the tuning of the resonant concentric line. The grid of tube Tis coupled to a suitable point on the inner surface of outer conductor 2' by means of a'lead 26 extending through an aperture in conductor I. The anode is grounded from a radio'frequency standpoint by means of lead 3'1. The filamentleads 28,'28 also pass through apertures in the inner conductor I and are coupled to points on the innersurface of the outer conductor 2' which have less radio frequency potential than the point of connectionto the grid lead 26; that is, the grid'isarranged to have greater coupling to'c'onduct'or'i' than the filapaths oif'low impedanc'e'to'radio frequency energy. In this manner, it is possible tosupply the electrodes of the :vacuum tube T with suitable polarizing potentials. The equivalent electrical circuit forFig. '4'is shown in Fig.4a, which clearly illustrates that the grid of tube '1 is excited periodicallyat higher radio frequency potentials than,'but'in phase with the'filamentfor best'oscillating conditions.

The. arrangement of Fig. 4 has the advantage of enabling minimization of reactance in electrode leads .to the vacuum tubes, and also minimization'of lead lengths. One way of reducing the reactance and lengths of electrode leads to a minimum in this arrangement is illustrated in Fig. 4b which'shows a crosasectionof Fig. 4 with certain mechanical details included. The lead 25 to the grid electrode of tube T is extremely short and is connected to'a metallic segment29 of relatively wide area mounted upon another metallic segment 38 but insulated therefrom 'by' a mica layer 39. Segment 38 is directly connected mechanically to the inner surface of outer conductor 2 andis capacitively coupled to segment 29 forming a path of low impedanceto radio frequency energy thereto. If desired, the filament leads 28, 28 may be similarly coupled'to conductor 2 of the-resonant concentric line.

Fig. 5 illustrates a high frequency tuned circuit of low power factor (high Q) in the form of a metallic resonant chamber 3Z,here shown as a right circular cylinder'having flat top and bottom surfaces,with means for deriving therefrom equal potentials of opposite instantaneous polarities. A resonant chamber of this general type, which may also takethe form of an hour-glass or sphere, is described indetail in the copending application of Philip S. Carter, Serial No. 249,711, filed January 7, 1939. For exciting the resonant chamber 32 there is provided any suitable source of oscillations 33, here shown conventionally in box form, coupled inductively to the chamber by loop 34. Connections 30 and 3! connect with oppositely located surfaces and extend through opposite sides of the chamber between which there is apotential gradient. These connections thus have produced in themopposite polarities which may be utilized in any suitable vacuum .tube translation circuit, such as an amplifier, pushpull or single ended, detector etc., or a load circuit.

What is claimed is:

1. In combination, a concentric line Whose inner and outer conductors have waves of opposite instantaneous polarities thereon, said inner conductor being hollow for at least a portion of its length, a connection from the inner conductor passing through an aperture in the outer conductor, and a connection from said outer conductor passing through an aperture in said inner conductor into the hollow portion thereof, both of said connections extending to a translation circuit.

2. In combination, a resonant circuit having a pair of conducting surfaces separated solely by space, means for producing in said chamber a periodically repeating electromagnetic field and a difference in potential between said pair of surfaces, a connection from one of said surfaces passing through anaperture in the other surface, and a connection from said last surface passing through an aperture in said first surface, both of said connections extending to translation apparatus. I

3. A-system in accordance with claim 2, characterized-in this that-saidresonant -chamlcker is a right circular cylinder, and said translation apparatus includes a vacuum tube circuit.

4. In combination, a concentric line resonator having a hollow inner conductor and a hollow outer conductor suitably coupled together to form a tuned circuit, a pair of vacuum tubes, a connection from a cold electrode of one vacuum tube extending through the interior of said inner conductor and through an aperture in said inner conductor to couple to a point on the inner surface of said outer conductor intermediate the ends of said outer conductor, and a connection from the corresponding cold electrode of said other vacuum tube passing through an aperture in said outer conductor to a point on said inner conductor intermediate the ends of said inner conductor.

5. In combination, a concentric line resonator having a hollow inner conductor and a hollow outer conductor, an end plate coupling together one end of one conductor to the adjacent end of the other conductor, a pair of electron discharge devices, a connection from an electrode of one device extending through the interior of said inner conductor from the end thereof at which said end plate is located and through an aperture in said inner conductor to couple to a point on the inner surface of said outer conductor intermediate the ends of said outer conductor, and a connection from a corresponding electrode of said other device passing through an aperture in said outer conductor to couple to a point on said inner conductor intermediate the ends of said inner conductor, said points being substantially equally spaced from said end plates.

6. An oscillator system in accordance with claim 5, characterized in this that said connections couple to the grids of said devices, said devices having anodes between which there is provided a parallel tuned circuit.

'7. An oscillation system in accordance with claim 5, characterized in this that said devices each include a grid and an anode, said connections being coupled at one end to said line resonator and at their other ends to said grids, a path of low impedance from said end plate to a point of zero radio frequency potential, and a tuned circuit coupled to the anodes of said devices.

8, In combination, a resonant chamber in the form of a closed conducting surface having a pair of substantially flat surfaces separated by etheric space, said pair of flat surfaces having a potential gradient therebetween, vacuum tube apparatus, a connection from said vacuum tube apparatus passing through an aperture in one of said flat surfaces and coupling to the other of said flat surfaces, and another connection from said vacuum tube apparatus passing through an aperture in said last flat surface and coupling to the first of said fiat surfaces.

9. A system in accordance with claim 8, characterized in this that the couplings between said connections and said flat surfaces are conductive for direct current.

10. In combination, a concentric transmission line having a hollow inner and a hollow outer conductor, a path of low impedance'between said conductors at one end, a load circuit at the other end of said transmission line, high frequency vacuum tube translating apparatus, a connection from said translating apparatus passing through the interior of said hollow inner conductor at the end at which said path of low impedance is located and passing through an aperture in said inner conductor to a point on the inner surface of said outer conductor, and another connection from said translating apparatus passing through an aperture in said outer conductor to a point on the outer surface of said inner conductor, said apertures and said points of connection being located substantially one-quarter of a wavelength from said path of low impedance, whereby said points of connection are points of high impedance to currents tending to flow over said inner and outer conductors toward said path of low impedance and the currents in said connections are in opposite directions.

11. Apparatus in accordance with claim 10, characterized in this that said connections constitute the inner conductors of concentric transmission lines, the outer conductor of one of which is a continuation of the inner conductor of said first concentric line and the outer conductor of the other 'of which communicates with the interior of the outer conductor of said first concentric line at the aperture in said last outer conductor, whereby said concentric lines constituting said connections are electrically in parallel with respect to the first concentric line.

12. Apparatus in accordance with claim 10, characterized in this that said load is a quarter wavelength radiator, and said translating apparatus is a push-pull radio transmitter.

13. In combination, a concentric transmission line having a hollow inner and a hollow outer conductor, a path of low impedance between said conductors at one end, a load circuit at the other end of said transmission line, high frequency vacuum tube translating apparatus, a connection from said translating apparatus passing through the interior of said hollow inner conductor at the end at which said path of low impedance is located and passing through an aperture in said inner conductor to a point on the inner surface of said outer conductor, and another connection from said translating apparatus passing through an aperture in said outer conductor to a point on the outer surface of said inner conductor, said apertures and said points of connection being located substantially one-quarter of a wavelength from said path of low impedance, whereby said points of connection are points of high impedance to currents tending to flow over said inner and outer conductors toward said path of low impedance and the currents in said connections are in opposite directions, said connections constituting the inner conductors of concentric transmission lines, the outer conductor of one of which is a continuation of the inner conductor of said first concentric line and the outer conductor of the other of which communicates with the interior of the outer conductor of said first concentric line at the aperture in said last outer conductor, whereby said concentric lines constituting said connections are electrically in parallel with respect to the first concentric line, additional connections extending from the conductors of said first concentric line at their other end, said additional connections also constituting the inner conductors of concentric lines which are electrically in series with respect to said first trans mission line, the outer conductors of said additional concentric lines being connected to the outer conductor of said first concentric line through a quarter wavelength sleeve surrounding the last end of said first line.

14. In combination, a conductive boundary enclosing a space, means for producing in said enclosed space a variable electromagnetic field w h p duces. a internal l a r die across a d spa e? sa d" ou d ry c m risi con fronting surfaces eachaof whichisprovided with arr-aperture, said-apertures being on an imaginary straight. line passing transversely to the longest axis of said boundary, connections from the. exterior 01; said boundary extendingpthrough said apertures to points on said conirontingsurfaces which carry potentials ofdesiredrelative magnitudes and which havena desired phase with respect to the direction ofsaid internal voltage gradient, and-a translation circuit coupled to said connections. a l

15. The combination with a balanced two conductor system, oii a coaxial resonatorhaving an inner and an outerconductor coupled togetherat o e d h cu h ap h o lo impedance toerier y i e o a i re u c on -c u t r; c sa d lan d s em b ing onn tedhe outer uraceo d inner cond to and e tend n across the spacebetween said inner-and outer conductorsand the other conductor of said balanced ystem be n co n c d t t e nner surfa of sa d. c t ru t and als te din acr ss the space between said inner and; outer conduc -l tors, the points of connectionof said-conductors of said balanced system to saidresonator bein suchthat the impedance'presented' by said-iresor nator to eachsideof said feeder is the same.

16. In combination, a conduotiveboundary enl sing a e. le trom neti field, he i terior' space thus being traversed bya voltage gradient whereas the exteriorspace is void ofsuch gradient, said boundary having a: pair, of apertures on opposite sides off said space and which are substantially the same distancefrom the ends of said boundary,pconnections externally of said boundary passing through. saidapertures and connected through leads of minimumlength to the inner surfaces of said boundary .on-opposite sides of said space, saidapertures and the points of connection; to the inner-surfacesvof said boundary being'so, located that the connections carry potentials of desired relative magnitudes and which are in phase, with-or reciprocaltothe direction of the internal voltage gradient, and a translation circuit coupled to said connections.

1?. In combination, a conductiveboundary enclosing a variable electromagnetic field, the 'interior space time being traversed by a voltage gradient Whereas-the; exterior space is void of such gradient, said boundary having apair: of apertur-es on opposite sides of said space and which are substantially the same-distancefrom the ends of said boundary connections externally of said boundary passing through said apertures and connected through leads of minimum length to the inner surfaces ofsaid boundary on opposite sides-of'said space, said apertures and the points of connection to the inner surfaces ofisaidboundary being so located that the connections" carry potentials of desired relative magnitudes and which are in phase;with:or reciprocal'tothedi-' rection of the-internal voltage gradient, the-interionspace of said conductive boundary having such dimensions that energy storage by-resonance is obtained, and an electron discharge device-circuit connected to=said connections. 1 I

18. In combination, a conductive boundary enclosinga variable electromagnetic field, the interior space thusbeing traversed'bya voltage gradient whereas the exterior space-isvoid ofsuch gradient, said-boundary having a p i o apertu es. chopp site sides of said space, connecti externally'of, said bo ndary passin thro h, apertures. and

connected to the inner surfaces of said boundary on-opposite sidesfof said space, said apertures and pointsof connection to'the inner surfaces of said boundary being so located that the connections carry potentials of desired relative magnitudes and which are in phase with or reciprocal to the direction of the internal voltage gradient, the space within said conductive boundary containing no conducting material, whereby said conductive boundaryforms a. wave guide or resonant chamber, and a translation circuit coupled to said connections.

I 19. The combination with a balanced two-conductor system, of: a coaxial resonator having an inner and anouter conductor coupled together at one end through a path of low impedance to energy of ;-the operating frequency, one conductor of'said balanced system being connected tothe outer surface of said inner conductor and extendingacross the space between said inner and outer conductors and the other conductor of said balanced. system being connected to the inner surface of said outer conductor and also extending across the space between said inner and outer conductors, the-points of connection of said; conductors of said balanced system to said surfaces being the same distanceirom one end of said resonator. I

20;, In combination, a balanced circuit each side of which comprises a coaxial line, an unbalanced circuit, and a concentric line whose inner and outer conductors are coupled together at one end by a path of low impedance to the operating frequency coupled between said balanced and unbalanced circuits, a connection from the inner conductor of oneof said coaxial lines to a point on the outer surface of the inner conductor of said concentric line which is approximately onequarter of a wavelength from said one end, a connection from the inner conductor of said other coaxial line to apoint on the inner'surface of the outer conductor of said concentric line which is also approximately one-quarter of a wavelength from said one end, and means for connecting said unbalanced circuit to the inner conductor of said concentric line.

21. The combinationwithabalanced two-conductor feeder line, of a coaxial line having-an'inner and an outer conductor, one conductor of said feeder being connected to the outer surface of said innerconductor and the other conductor of said feeder being connected to the inner surface of said outer conductor, the points of, connection of said feeder conductors to said surfaces being one-quarter wave-length from one end of said coaxial line.

22. In combination, a concentric line resonator having a hollow inner conductor and a hollow outer conductor suitably coupled together to form a tunedcircuit, a pair of vacuum tubes, a connection from a cold electrode of one vacuum tube outer conductor suitably coupled together to form a tuned circuit, apairof vacuum tubes, a connection from a coldelectrode of one vacuum tube extending through the interior of said inner conductor and through an aperture in said inner conductor to couple to a point on the inner surface of said outer conductor intermediate the ends of said outer conductor, and a connection from a cold electrode of said other vacuum tube passing through an aperture in said outer conductor to a point on said inner conductor intermediate the ends of said inner conductor, said points on said inner and outer conductors being substantially equally distant from one end of said concentric line resonator.

24. In combination, a balanced circuit each side of which comprises a coaxial line, an unbalanced circuit, and a concentric line coupled between said balanced and unbalanced circuits, a connection from the inner conductor of one coaxial line of said balanced circuit to the inner conductor of said concentric line, a connection from the inner conductor of the other coaxial line of said balanced circuit to the inner surface of the outer conductor of said concentric line, the outer conductors of said coaxial lines being connected together, and a connection from said unbalanced circuit to the inner conductor of said concentric line.

25. A system in accordance with claim 24, characterized in this that the outer conductors of said coaxial lines of said balanced circuit are connected to the outer conductor of said concentric line. i

26. In combination, a balanced circuit each side of which comprises a coaxial line, an unbalanced circuit also comprising a coaxial line, and a concentric line coupled between said balanced and unbalanced circuits, a connection from the inner conductor of one coaxial line of said balanced circuit to the inner conductor of said concentric line, a connection from the inner conductor of the other coaxial line of said'balanced circuit to the inner surface of the outer conductor of said concentric line, and a connection from the inner conductor of the coaxial line of said unbalanced circuit to the inner conductor of said concentric line, the outer conductors 'of all said coaxial lines being connected to the outer conductor of said concentric line.

27. The combination with a balanced two-conductor system, of a coaxial resonator having an inner and an outer conductor coupled together at one end through a path of low impedance to energy of'the operating frequency, one conductor of said balanced system being connected to the outer surface of said inner conductor and extending across the space between said inner and outer conductors and the other conductor of said balanced system being connected to the inner surface of said outer conductor and also extending across the space between said inner and outer conductors, the points of connection of said conductors of said balanced system to said surfaces being each substantially one-quarter of-a Wavelength at the operating frequency from one end of said resonator.

28. In combination, a concentric line whose inf ner and outer conductors have waves of opposite instantaneous polarities thereon, said inner conductor being hollow for at least a portion of its length,.a short circuiting element across the conductors of said concentric line, a connection from the inner conductor passing through an aperture in the outer conductor, and a connection from said outer conductor passing through an aperture in said inner conductor into the hollow portion thereof, both of said connections extending to a translation circuit, the junction points of said last connections to the conductors of said concentric line being each an odd multiple including unity of a quarter wavelength at the operating frequency away from said short-circuiting element. 7

29. In combination, a conductive boundary enclosing a variable electromagnetic field, the interior space thus being traversed by a voltage gradient whereas the exterior space is void of such gradient, said boundary having a pair of apertures on opposite sides of said space and which are substantially an odd multiple including unity of one-quarter wavelength at the operating frequency from one end of said boundary, connections externally of said boundary passing through said apertures and connected through leads-of minimum length to the inner surfaces of said boundary on opposite sides of said space, said apertures and the points of connection to the inner surfaces of said boundary being so located that the connections carry potentials of desired relative magnitudes and which are in phase with or reciprocal to the direction of the internal voltage gradient, and a translation circuit coupled to said connections;

30. In combination, a balanced circuit, each side of which comprises a coaxial line, an unbalanced circuit, and a concentric line resonator coupled between said balanced and unbalanced circuits, a connection from the inner conductor of one coaxial line of said balanced circuit to the outer surface of the inner conductor of said resonator, a connection from the inner conductor of the other coaxial line of said balanced circuit to the inner surface of the outer conductor of said resonator, and means for connecting said unbalanced circuit to the inner conductor of said resonator.

31. In combination, a balanced circuit, an unbalanced circuit, and a concentric line resonator coupled between said balanced and unbalanced circuits, a connection from one side of said balanced circuit to a high voltage point on the outer surface of the inner conductor of said resonator, a connection from the other side of said balanced circuit to an adjacent point on the inner surface of the outer conductor of said resonator, both of said connections encircling substantially the same amount of flux within said resonator, and a connection from said unbalanced circuit to said resonator.

32. In combination, a tuned oscillatory circuit in the form of a resonant hollow enclosure having a pair of spaced conducting surfaces adapted to have opposite instantaneous polarities thereon, a balanced circuit, an unbalanced circuit, connections from both sides of said balanced circuit to said spaced conducting surfaces, and means coupling said unbalanced circuit to said resonant hollow enclosure.

, .33. In combination, a balanced circuit, an unbalanced circuit, and a concentric line resonator coupled between said balanced and unbalanced circuits, a, connection from one side of said balanced circuit to a point on the outer surface of the inner conductor of said resonator, a connection from the other side of said balanced circuit to a point on the inner surface of the outer conductor of said resonator, both of said connections encircling substantially the same amount of flux within saidre'sonator, and a connection from said unbalancedcircuit to a point on the inner conductor of said resonator.

34. In combination, a balanced circuit, an unonator, both of said connections encircling substantially the same amount of flux within said resonator, and a connection from said unbalanced circuit to a point on the inner conductor 5 of said resonator.

NILS E. LINDENBLAD.