US2377680A - Electrical apparatus adapted to operate at very high frequencies - Google Patents

Description

June 5, 1945. D. c. ESPLEY EI'AL 2,377,680

ELECTRICAL APPARATUS ADAPTED TO OPERATE AT VERY HIGH FREQUENCIES Filed Jan. 2, 1942 FIG. 1.

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Patented June 5, 1945 ELECTRICAL APPARATUS .ALDAPTED To l OPERATEATVEBY HIG HT REQUENCI ES Dennis Clark Espley, North Wembley, and John .Walter Ryde London WL14,England, assignors i l p g. touThe General. Electric Company Limited, l a a London W. 0.2, England ApplicationJanuary 2, 1942, Serial No. 425,430 v In Great Britain November'4,1940g a 1 23 Claims. (c aste-3e).

This invention relatesto electrical apparatus adapted to operate at highirequencies (an-d more especially" at frequencies corresponding. to wave- ,length invacuo of less than 1 metre) ofthe type comprising a pair of conductors arranged side by side and cooperating to form a transmission line along which there are standing electric waves. The conductors may be, for example, apair of parallel rods or a pair of concentric cylinders.

In such apparatus oscillating Voltages maybe developed between correspondingpoints on the conductors that'a're very muchhigher than any steady voltage applied to the apparatus; the power of the oscillations that can be generated in the apparatus may then be limited by the passage open atfone endand oupled at a given point spaced-from thesaidj Ioneend. to a wave-signal translating apparatus to develop along the line standing waves of potential having a maximum value limited pby the corona dischargebetween X the conductors at theaforesaid open end; The

of a discharge through the air between the conductors or by the formation of a}corona on one or both of them. The object of this inventionis to l l increase the limit set to the powerby this possi bility. a 1 A It is well known that a discharge from or a corona on a conductor can be suppressed by surrounding the conductor with a dielectric of a-dielectric strengthand dielectric'constant greater than that of air. Solid and liquid dielectricsof high dielectric strength are undesirable in apparatusof thetyp'e specified because the dielectric loss .inthem is too great. The other alternatives are a vacuum or a gas at a pressure higher than atmospheric. But theme of these dielectrics requires the presence of a sealed envelope around the conductor; theproblem then arises of making connection "between the conductor inside theenvelope andythe rest of the apparatus outside without incurring the danger of a discharge .orfcorona. This problem can be solved by arranging matterstso that the connecting partis at or near a voltage node of the oscillations, so that the part is exposed only to small oscillating voltages. According to the invention a high-frequency electric oscillation generator comprises a pair of thermionicvalvesatleast two of the leads to which co-1operate to form a transmission line along which there are standing electric waves and wherein at least one of the leadsis enclosed throughout the greater part of its length in a sealed envelope, the pointswhere any part of the one lead emerges from theenvelope for connection toa part of the associated one ofithe valves, that is not grounded for high-frequency oscillations, being in the neighborhood of a voltagenode of'the oscillations. l F g .In accordancewith a particular formof the invention, a high-frequency wave-signal translating system comprises a pair of conductorscoopsystem; includes a non-conductive sealed envelope enclosingthe open end of atleast oneof the'conductors ina medium at such pressure as substantially to increase the maximum potential at which the corona discharge is initiat'edbetween the conductors at the open end of theline, the envelope terminating at one end alongthe aforesaid one conductor substantially only in the neighborhood therealong. t

If there is of avoltage node of the standingwave developed a high vacuum within the envelope there will be little difiiculty in securing the'necessary. dielectric strength. But sincesome power is always dissipated in the conductors, it maybe difficult to cool them suffi ciently. Then the sealed envelope may containcompressed gas. Carbon dioxide is a convenientgas; for; in orderto avoid the difiicultyjofsealing ch 9, vesselcontaining gas {at high pressure, thegas may becondensedby cold duringthesealing off. (No novelty claimed for this deviceperse.) Alternatively, vapours,

such asthose of carbon tetrachloride, or dichlorodifiuoro-methane, which are known to have great dielectri f trength, maybe used in place of carbon dioxide. i l

Apparatus of the type specified is often operated at high altitudes where the atmospheric pressure is muchless than normal. It may happen then that acorona orldischarge occurs only when the apparatus is taken to such altitudes. Then the sealed envelope maybe filled with air at normal atmospheric pressure; for in the circumstancesof use the gas will be compressed, i. e.,

at a pressure higher than that oi the surroundingregion.

Two embodiments of theinvention will now be described by Way of example with reference to theaccompanying drawing,inwhich Figure 1 is a sectional diagram of part of a high frequency electric oscillation generator;

erating to provide a resonanttransmissionline 1 Figure 2 is a diagram of the samegenerator, 'drawn toa smaller scale, and showing elements not appearingin Figure 1; and i l Figure 3 is a sectional diagram of tive embodiment.

an alterna- In Figs. 1 and 2 a pair of thermionic valves I, l, arranged to operate in push-pull, have external anodes 2, 2'. The anode areeffectively continuous with the copp r discs, 3, 3', into holes which they are set. 4, 4' arevthe cathode con nections emerging at one end of each valve; as shown in Figure 2, these connect to lines I4, I4, each consisting of a pair of concentric conductors insulated from one another. One end of the cathode heating element of Valve I is connected to the inner conductor of the line I4, while the other end of the heating element and the oathode emitting surface are connected in common to the outer conductor of line I4. The heating element and cathode of valve I' are similarly connected to the conductor of line M. The lines I4, l4 form a parallel transmission line terminated by an adjustable tuning bridge I5. The cathode heater battery is denoted by I6. 5, 5 are terminals to the control grid emerging at the other end of each valve.

The said pair of conductors, being straight A parallel rods, which are attached at one end to the grid terminals 5, 5', include straight parallel rods 6, 6'. Standing waves are set up along these conductors and the length of the conductors is so adjusted relative to the wave-length of the oscillations thatthe ends joined to 5, 5' are at or near a voltage node. Each rod 6, 6' is enclosed within a sealed glass envelope I, 'I' filled with carbon dioxide to a pressure of 2 atmospheres or more. i I

Inorder that 6, 6' may be connected to 5, 5, the terminal 5 or 5' is a threaded plug projecting from the bottom of a metal thimble 8, 8 sealed at its edge to the glass 9, 9' of the valve. (This construction is known per se.) The end of 6, 6 is a similar plug l0, l brought out similarly from the end of the envelope 1, I. II, II are metal connecting pieces, having a threaded hole at each end intov which the plugs 5, and

crating to provide a resonant transmission line open at one end and coupled at a given point spaced from said one end to a wave-signal trans- Ill, I0 are screwed. Exact tuning can be efiected by adjusting the lengths of the pieces I I, I I.

All the parts mentioned are mounted on the metal plate I2, provided with ducts l3 through which a coolant is circulated.

The plate I2 is grounded for high-frequency oscillations and is connected through a battery I'I, supplying the anode current for the valves, to each of the cathode lines I4, l4. Conventional grid-leak resistors I8, I8 are connected in series between the connecting pieces II, II, and the junction of the resistors is connected to one terminal of the battery I6. The grids of the valves I, l' are thus operated above ground for both high-frequency and unidirectional-bias potentials.

The open-ended transmission line formed by the conductor rods 6, 6', the connecting pieces II, II, and the grid leads within the envelopes of the valves I, I thus has an elctrical length M2, where A denotes the wave length'of the standing waves in the line; and the part of this line constituted by the enclosed conductor rods 6, 6' has an .electrical length substantially M4.

InFigure 3, a thermionic valve I, constructed and mounted similarly to each of the valves I, I in Figure 1, is associated with a pair of concentric cylindrical conductors 6A and 6B. The inner cylindrical conductor 6A, which is attached by the connecting piece II to the grid terminal 5 of the valve, is enclosed within the sealed glass envelope I, which may be evacuated or charged with any of the gases or vapours hereinbeiore specified. The outer cylindrical conductor 6B, which is not enclosed in an envelope, is mounted on th metal plate I2.

What We claim as new is:

1. A high-frequency wave-signal translating system comprising, a pair of conductors co-oplating apparatus to develop along said line standing waves of potential having a maximum value limited by the corona discharge between said conductors at said open end, and a nonconductive sealed envelope enclosing the open end of at least one of said conductors in a medium at such pres.- sure as substantially to increase the maximum potential at which a corona discharge is initiated between said conductors at said open end of said line, said envelope terminating at one end .along said one conductor substantially only in the neighborhood of a potential node of the standing wave developed therealong.

2. A high-frequency wave-signal translating system comprising, a pair of parallel conductors co-operating to provide a resonant transmission line open at one end and coupled at a given point spaced from said one end to a wave-signal translating apparatus to develop along said line standing waves of potential having a maximum value limited by the corona discharge between said conductors at said open end, and a pair of nonconductive sealed envelopes enclosing the open ends of individual ones of said conductors in a medium at such pressure as substantiallyto increase the maximum potential at which a corona discharge is initiated between said conductors at said open end of saidline, each of said envelopes terminating at one end along the conductor enclosed thereby substantially only in the neighborhood of a potential node of the standing Wave developed therealong.

3. A high-frequency wave-signal translating system. comprising, a pair of concentric cylindrical conductors co-operating to provide a resonant coaxial transmission line open at oneend and coupled at a given point spaced from'said one end to a wave-signal translating, apparatus to de velop along said line standing waves of potential having a maximum value limited by the corona discharge between said conductors at said open end, and a nonconductive sealed envelope enclosing the open end of the inner one of said conductors in a medium at such pressure as substantially to increase the maximum potential at which a corona discharge is initiated between said conductors atsaid open end of said line, said envelope terminating at one end along said inner,

conductor substantially only in the-neighborhood of a potential node of the standing wave developed therealong.

4. A high-frequency wave-signal translating system comprising, apair of conductors co-operating to provide a resonant transmission line open at one end and coupled at a given point spaced from said one end to a wave-signal translating apparatus to develop along said line standing waves of potential having a maximum value limited by the corona discharge between said conductors at said open end, and a nonconductive evacuated envelope enclosing the open end of at lease one of said conductors substantially to increasethe maximum potential at which a corona discharge is initiated between said conductors at said open end of said line, said envelope terminating at one end along said one conductor substantially onlyin th neighborhood of a potential node of the standing wave developed therealong. 5. A high-frequency wave-signal translating system comprising, a pair of parallel conductors co-operating to provide a resonant transmission line open at one end and coupled at a given point lating apparatusto:developalone said line stande ing waves of potentialhaving amaximu'm value limited bythe :corona discharge between said conductors atsaid open end, and apair of non conductive evacuated envelopes? enclosing the open ends of individual ones of said conductors substantially to increase the maximum potential A 2,377,680 spacedfrom said'one endto awave-signaltrans- 1 to a wavewsignal translating apparatus :to de- A velop along said line standing wavesof potential having a maximum value limited by the corona at which a corona discharge is initiated between said conductors at said open end of said line, each inl'the neighborhood of apotential node of the standing; wave developed therealong.

A a high-frequency wave-signal translating system comprising, a pair of concentric cylindrical conductors co-operating to provide airesonant coaxial transmission line open at one end and coupled at a given point spaced from said one end to a wave-signal translating apparatus to develop along said line standingwaves of potential having a maximum value limited by the corona discharge betweensaiduconductors at said open end, and a nonconductive evacuated envelopeenclosing the open end of theinner oneof said conductors substantially to increase the maximum potential at which a corona discharge is initiated between said conductors at said open end of said line, said envelope terminating at one end along said inner conductor substantially only in the neighborhood of a potential node o fthe standing wave developed therealong.

discharge between said conductors at said open end, and a nonconductive sealedenvelope enclospotential atwhich a corona discharge isjinitiated between said conductors at saidopen end of said line, said envelope terminating at one end along ,said inner conductorlsubstantially only in the 7. A high-frequency wave-signal translating system comprising, ap'airrof conductors co-operating' to provide a resonant transmission line open at one endand coupled at a given point spaced from said one endto a wave-signal translating apparatus to develop along said line standing wavesof potential having a maximum value limited by the corona discharge between said con- (meters at said open end, and a nonconductive sealed :envelope'enclosing the open end of at least one of said conductors in awgaseous medium at superatmospheric pressure substantially to in crease the maximum potential at which a corona discharge is initiated between saidconductors at said; open end of saidlineysaid envelope terminating at one end along said one conductor substantially only in the neighborhood of a potential node of the standing wave developed therealong.

i8.A high-frequency wave-signal; translating system comprising, a pair of parallel rod conductors co-operating toprovide a resonant transmission line open at one end and coupled at a'given point spaced from said one endyto a wave-signal translating apparatus to develop along said'line standing Waves of potential having a maximum valuelimited by the corona? discharge between said conductors at said open end, and a pair of nonconductivesealed envelopes enclosingthe open endsof individual ones of said conductorsin a gaseous medium at superatmosphericpressure standing wave developed therealong.

9. A high-frequency wave-signal translating system comprising, a pair of concentric cylindrical conductors co-operating to provide a resonant coaxial transmission line open at one and coupled at a givenpoint spaced from said one end neighborhood of a potential node of the standing wavedeveloped therealong. A

10. A high-frequency wave-signal translating system comprisinga pair of conductors co-operating toprovide a resonant transmissionline open at one end and coupled at a given point spaced from said one end to a twave-signaltranslating apparatus to develop along said line standing waves of potential having a maximum value limited by the corona discharge between said conductors at said open end, and a nonconductive which a corona discharge is initiated between said conductors at said open end of said line, saidenvelope terminating at one end along said one conductor substantially onlylin the neighborhood of a potential node of the standing wave developed therealong.

1 A ll. A high-frequency wave-signal translating system comprising, a pair of conductors co-operatingtoprovide a resonant transmission line 'open 7 atom end and coupledat a given pointspaced from said one end to a wave-signal translating apparatus to develop along said line standing waves of potentialhavinga maximum value limited bythe corona discharge betweensaid conductors at said openenol, and a nonconductive sealed envelope. enclosing the open end of at'least A A one of said'conductors in the vapour of ama terial having great'dielectric strength andat such pressure as substantially to increase the maximum potential at which'a corona discharge is initiated between said conductors at said open end of said line, said envelope terminating at one end along said one conductor substantially only in the neighborhood of a potential node of the standing wave developed therealon'g. J it 3 12. A high-frequency wave-sign'al'translating system comprising, a pair of conductors co-oper ating toprovide a resonant transmission line open at one end and coupledat a given point spaced from said one end to a wave-signal translating apparatus to develop along said line standing waves of potential having a maximum value limited by the corona discharge between said con ductors at saidopen end, and a nonconductive sealed envelope enclosingthe open end of at least one of said conductors in carbon-tetrachloride vapour at such pressure as substantially to increase the maximum potential at which a corona discharge is initiated between said conductors: atsaid open end of said line, said envelope terminating at one end along said one conductor substantially only'in the neighborhood of a potential node of the standing wave developed therealong.

13. A high-frequency wave-signal translating 1 system adapted to be used at high altitudes comprising, a pair of conductors co-operating to provide a resonant transmission line open atoneend and coupled at a given point spacedfrom said one end to-a wave-signal translating aptions.

paratus to develop along said line standing waves ofp'otential having a maximum value limited by the corona discharge between said conductors at said open end, and a nonconductive sealed envelope enclosing the open end of at least one of said conductor in air at normal atmospheric pressure substantially to increase the maximum potential at which a corona discharge is initiated between said conductors at said open end of said line when said system is operated at said high altitudes, said envelope terminating at one end along said one conductor substantially only in the neighborhood of a potential node of the standing wave developed therealong.

- '14; A highfrequency electric oscillation generator comprising a pair of thermionic valves at least two" of the leads to which co-operate to for'ma transmission line along which there are standing electric waves and wherein at least one said lead is enclosed throughout the greater part of its length in a sealed envelope, the points Where any part of said one lead emerges from said envelope for connection to a part of the associated one of said valves; that is not'groundecl for high frequency oscillations, being in the neighborhood of a voltage node of the oscilla- 115.-A high frequency electric oscillation generator comprising a pair of thermionic'triodes operating in push-pull and whose grid leads are parallel rods which co-operate to form a transmission line along which there are standing electric waves, wherein each said grid lead is enclosed throughout the greater part of its length in a sealed.v envelope containing carbon dioxide at superatmospheric pressure and the whole of the part of each said grid lead lying between said sealed envelope and the envelope of the corresponding thermionic valve is in the neighborhood ,of a voltage node of the oscillations.

17. A high frequency electric oscillation generator comprising a pair of thermionic triodes operating in push-pull and whose grid leads are parallel rods which co-operate to form a transmission line along which there are standing electric waves, wherein each said grid lead is enclosed throughout the greater part of its length in a sealed envelope containing the vapour'of a material having great dielectric strengthand the Whole of the part of each said grid lead lying between said sealed envelope and the envelope of the corresponding thermionic valve is in the neighbourhood of a voltage node of the oscillations.

18. A high frequency electric oscillation generator'comprising a air of thermionic triodes operating in push-pull and whose grid leads are high dielectric strength. I

21.. A high frequency electric oscillation genparallel rods which co-operate to form an openended transmission line of electrical length-M2 along which there are standing electrical waves of wavelength X and wherein each said grid lead is enclosed throughout a lengthof substantially M4 from the open end of said line in a sealed envelope. I

19. A high frequency electric oscillation generator comprising a pair of thermionic triodes operating in push-pull and whose grid leads'are parallel rods which 'co-operate-to form an openended transmission line of electrical length M2 along which there are standing electrical waves of wavelength A and wherein each said grid lead is enclosed throughout a length'of substantially M4 from the'open end of said line ina sealed envelope containing carbon dioxide at 'superatmospheric pressure. i

20. A high frequency electric oscillation generator comprising a pair of thermionic triodes operating in push-pull and whose grid leads are parallel rods which co-operate' to form an openended transmission line 'of electrical length M2 along which there are standing electrical Waves of wavelength A and wherein each said grid lead is enclosed throughout a'length of substantially M4 from the o'penend of said line in a sealed envelope containing the vapour of a material of eratorcomprising a pair of'thermio'nic triodes operating in push-pull and whose gridleads are parallel rods. Which-co-operate toform a transand the envelopeof the corresponding thermionic valve is in the neighbourhood of a voltage node of the oscillations and wherein the cathode leads of said valves form a parallel line terminated by an adjustable bridge for tuning.

22. A high frequency electric oscillation generator comprising a pair of thermionic triodes operating in push-pull and whose grid leads are parallelrods which co-operate to form an openendedtransmission line of electrical length'M2 along which there are standing electrical waves of wavelength x, wherein each said grid lead is enclosed Ithroughouta length of substantially M4 from the open-end of said linein a sealed envelope'and wherein the cathode leads of said valves form a parallel line terminatedby an adjustable bridge fortuning.

23. A high frequency electric, oscillation generator comprising a pair of thermionic triodes operating in push-pull and whose grid leads are parallel rods which co-operate to form an openended transmission line of electrical length M2 along which there are standing electrical waves of wavelength x, wherein each said grid lead is enclosed throughout a length of substantially M4 from the open end of said line in a sealed envelope containing carbon dioxide at superatmospheric pressure and wherein the cathode leads of said valves form a parallel line terminated by an adjustable bridge for tuning. 7/

DENNIS CLARK ESPLEY.

JOHN WALTER RYDE.

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