US2333295A - Ultra high frequency electron discharge device - Google Patents

Description

Nov. 2, 1943. G. P. cHEvl'GNY ULTRA-HIGH FREQUENCY ELECTRON DISCHARGE DEVICE 3 Sheets-Sheet 1 FIGO 2l Filed June 5, 1941 le f +l/7 FIG. 3.

A RNEY Nov. 2, 1943. G. P. CHEVIGNY ULTRA-HIGH 'FREQUENCY ELEGTRON DISCHARGE DEVICE F'led June 5, 1941 3 Sheets-Sheet 2 FIGS.

INVENTOR A ORNEY NOV 2, 1943- G. P. cHEvlGNY 2,333,295

ULTRA-HIGH FREQUENCY ELECTRON DISCHARGE DEVICE Filed June 5, 1941 3 Sheets-Sheet 5 FIGB.

Patented Nov. 2, 1943 ULTRA HIGH FREQUENCY ELECTRON DISCHARGE DEVICE Georges Paul Chevigny, New York, N. Y., assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application June 5, 1941, Serial No. 396,656 In France December 26, 1940 (Cl. Z50-27.5)

16 Claims.

The present invention relates to oscillatory circuits for very short waves and particularly to oscillatory circuits for very high frequency electron discharge tubes which make use of impedances of the tube itself.

It is an object of the invention to provide an improved form of electron discharge device for operation at very high frequencies.

It is another object to provide an improved form of electron discharge device having low resistance losses and radiation characteristics.

Another object of the invention is to provide means for making a given tube operatel at the highest possible frequency as determined by its structure.

It is another object of the invention to provide improved oscillatory circuit structures in which the electron discharge tube or tubes employed are contained Within the circuit structure, so that lead-in connection impedances are minimized.

Other objects and further features of novelty and invention will hereinafter become apparent from a reading of the following specification in conjunction with the drawings included herewith. In said drawings,

Fig. l represents a well known Colpitts oscillator circuit;

Fig. 2 represents a form of the same circuit for operation at its highest frequency limit;

Fig. 3 represents a symmetrical oscillating circuit incorporating features of the circuit of Fig, 2;

Fig. 4 represents schematically and in partial section a preferred form of oscillating circuit in accordance with certain features of the invention;

Fig. 5 is a more detailed broken-away perspective showing of the oscillating circuit of Fig. 4;

Fig. 6 shows schematically another form of oscillating circuit incorporating features of the invention;

Fig. 7 represents a symmetrical arrangement of oscillating circuit similar to that of Fig. 6;

Fig. 8 represents another form of oscillating circuit incorporating features of the invention; and- Fig. 9 represents a more detailed showing of the circuit of Fig. 8.

In the familiar Colpitts oscillator circuit of Fig. 1 the grid circuit of an electron discharge tube I includes on the one hand a grid capacity to earth Cg and on the other hand a grid inductance Lg which latter itself may be grounded through a coil Ig and a resistance Rg. The plate circuit of tube I includes on one hand a capacity to earth Ca and on the other an inductance La, which latter is connected to high voltage supply HT through a coil la. The two circuits just described are interconnected by the capacitance C inserted between the ends of inductances Lg and La remote from the electrodes, thus assuring av coupling between the two circuits. Such a circuit is well known and operates in accordance with well-known principles.

Now, in order to obtain higher operating frequencies, any external impedances for compensating for inter-electrode and lead-in impedances at high frequencies must befurther reduced so that the upper operating frequency limit circuit is approached. Theoretically, this limit may be reached when the grid and plate inductances consist solely of inter-electrode and lead-in inductances and when the oscillating circuit capacitance is merely the inter-electrode capacity of the tube.

Fig. 2 shows a full development of such a theoretical circuit for operating at'its upper frequency limit, reference characters for the various elements being the same as in the case of Fig. 1. The external circuit includes a simple connection Ill having a capacitance C for blocking continuous current. The internal grid-to-plate capacitance of the tube is indicated diagrammatically at Cag, and the grid-to-lament capacitance and plate-to-lament capacitances as Cg and Ca, respectively. The filament may be supplied through independent coil or other means If.

Even though the external connection I0 represents a minimum of inductance in the form shown, this inductance may be too much if the upper oscillating frequency limit for the ytube structure is to be obtained. In order further to reduce this inductance, features of the invention provide alternate means for more nearly approaching this limit by employing a conductive tubular screen about the axis of the tube element (or elements of the tubes if more than one are used) instead of line I0 and condenser C as above described. Such an embodiment is shown schematically with dotted lines in Fig. 2,r by the line I0 and the capacitative coupling C', which represents the capacitance extending about this tubular screen. The screen I0 is preferably symmetrical about the axis of the electrode structure, extending longitudinally thereof. vThe impedance of the connection (C, Ill) is thereby materially reduced since, as is well known, the impedance of a coaxial structure or a substantially coaxial structure is less than the impedance of a structure having substantially parallel elements, and further, since we may consider the closed circuitl obtained in this manner as a coaxial structure.

A two-tube oscillatory circuit may'also be made in accordance with these considerations as shown in Fig. 3 in which two tubes I and I are shown with their plate circuits interconnected and arranged end-to-end within a tubular screen I 0. With this multiple arrangement the capacitative coupling (corresponding to C or C') is not em ployed since the tubular screen is only connected to grids. The plate and lament supply circuits must traverse the screen Ill', and it is accordingly considered preferable to supply laments through relatively high impedances. Such a tube circuit arrangement will have very slight energy dissi` pation because of its reduced resistance Vand its negligibly small radiation-hence, it is considered o physically closed circuit from an electrical point' of view, and tubes the active portions of which are arranged Within the space thus dened and enclosed, the electrical connections being made in such a way that the circuit oscillates at its high frequency limit.

In the embodiment schematically shown in Fig. 4, the electron discharge tube comprises an anode II, which may or may not be cooled, hav!- ing a reentrant cavity I2 Within which the other electrodes are arranged, and an insulating envelope I3 sealed to this anode II. In a preferred form, the anode is generally cylindrical and symmetrical vabout a longitudinal axis. The connection tothe grid electrode I4 is shown extending generally radially outwardly 'and is sealed to' the insulating envelope I3 at I5. In' the form shown the grid connection extends conductively outside the tube by meansof a conductive shell f6 surrounding the tube for a portion oi its length. The shell I6 may be terminated with a flange `I1 which, together with a flange I8 associated with another and similar shell I9, forms a capacitance C, the latter shell I9 surrounding the other p'ortion of the tube'and being directly and conducvtively connected to the anode II. The filament 20 may be supplied by appropriate means If, -energy so supplied being passed through insulating envelope I3 at the' grid end ofthe tube. Other electrodes if desired may also be supplied in this manner, the leads-in being preferably coaxial.

'In the external circuit comprising the two shells I and I9 and'each side of the capacitative vcoupling II'-I, one side is connected to 'ground throug'h'a coil Ig and resistance Rg, and high voltage is supplied to the other side through a C011 la. Y

It will b'e appreciated that operation of the oscillating circuit just described is analogous 'to thatof Colpitts oscillator of Fig. 2. For "that reason, no operating details are considered necessary.

Fig. 5 is a perspective and partlyv broken away view of a preferred embodiment of an o's'cillati' constructed in accordance with considerations which have been indicated as desirable. Reference characters' designating correspondingel'ef ments are repeated throughout Figs. 4, 5,6 and 7.

Viewing the electron discharge' device of Fig'. 5 from' the outside'a portion of the anodeII may be seen extending outside the glass envelope I3. This portion of the anode I I may be divided into a number of longitudinally extending su'ch as 2I, for natural or other cooling o i the anode. The shell I9, shown securely connected through the'ano'de, for example by clamping means 22, is preferably of rsubstantially hemispherical for'm and includes apertures 23 which, in making -for lighter construction, permit better cooling 4of the tube. The ilange I8 of the shell I'9'is space'd'frcm the aange I1 or sneu rs so that the twoV flanges may cooperate to form a capacitative 'chupling which will block continuous current. A uniorm spacing is preserved by insulator spacers 2d, one of which is shown in cross section on the drawings. The substantially hemispherical shell I6 may likewise b e provided with similar venting opening 25, 'and further includes an opening 2G to permit the free entrance of connections 2l and 28 to the ffillairieriht.y The portion of shell I6 enr length.

5 closing the grid connection 29 of the tube is pro- 4the shell I6 may be made 'at the' end of this tubular extendin'gmember, for example; by means df a collar Aor clamp 3l which rigidlysecures the tubular member 30 within aconductirig tube 32.

This tube 32, in conjunction with tubes 33 and Si,

which are connected in asimilar way for feeding the filament, serves as a transmission line' `and may therefore replace' the coils -I andV Igof Fig. 4 by being made equal, say, to a quarter wave These tubes, which are substantially a quarter wave length or a multiple thereof, may be mounted on plate membersV 3,5 `separated by an insulating plate member 35',I which may be al por*- tion of a base 3l, and from the externalv shield ing rneans 38 to which the insulation is fixed by clamping means. I The shield` 38 is shown partly broken away in Fig. '5; it must beclosed at its upper end and includes' ventilation holes v39 in order to permit cooling of the circuit structure. An insulated part 40 is provided as shown to en'- able connection to be A'made to the anode 4| through the` shield.V The shield is also pierced at other portions to permit coupling `plates i2 and 43 respectively to be capacitat-lvelyconnected to the grid and plate circuits of the Loscillator and also connection t'o load line v4Il. o Y

Another embodiment is shown schematically in Fig. 6, in which a conductor tubev 5t, of copper for example, co'axially surrounds a; tube having an electrode arrangement similarl to that of Fig. 4, the anode I I extending Aa quarter wave-length or multiple thereof from the sealing connection to theenvelope I3. vThis extensionwhen considered Jwith the 'corresponding portion vof a copper ytube `which is coaxial with the anode and he'nce with Vthe general structure of the tube, constitutes a; transmission line equivalent toY coil la. The conductor tube vat'otheanodeend 5I is provided with an aperture 52 'to' permit high voltage supply to the anode. The anode II is oapaoitat'rvely coupled `to the copper 'tube 50 'm the immediate vicinity of the'envelope-anod'e "seal by `means vo'f a circular conductive 'plate /53 directly "connected 'to'theanoda by soldering or brazing'for example', and is provided with an annular flat flange "54 Whichwith thecorresponding portion of ,tube" 5I) constitutes Aa capacitance. The grid lead, which 'is preferably circulan'maybe directly and "conducti'vely vconnected to the tube 50, -as' shownjat 55. At this g'ridend, thetub 50 is' extended from the Iconnection 55"'2'1. length eolualto substantially a' quarterv wave l'en'gth'of the Loperative frequency or a vmultiple thereof. The ltube'fll is terminate'd'witha circurn'ferentially'.extending angeis'which may be capacitatiyely associated with' ground, 'assh'owm {"If desired', th'"ilange""`5li :nay-te directly connected 4to earth by mea' s' or a resistancenashunting the carin-toenangegst 'capacitance'. Within "the tllb'e 5U the flfafflt supply leads 51 may be similarly extended and coupled to earth as shown bythe plates 58. These connections comprise, together with the portion oi' tube 50 which surrounds them, a high impedance line which may serve the purpose of the coil lf of the preceding drawings. In this way, the oscillating circuit of Fig. 6, is so proportioned that a highV impedance line is formed between the filament and the grid and high voltage supply from the anode is made over a high impedance line. Such an arrangement makes for substantially reduced radiation or resistance losses and hence substantially improved impedance and voltage characteristics, while at the same time making a very simple circuit which will operate at ultra-high frequencies.

Another embodiment of an oscillating circuit which may provide the same advantages is shown in Fig. '7 in which two electron discharge tubes are shown having a direct common plate connection in order to connect them in push-pull. It is clear that a single tube may be provided having two electrode systems and a common anode, hollowed out at both ends, instead of the two tube structures shown. High voltage plate supply may be introduced laterally through a potential connection, while the conductive tube 50 may be extended on both sides a quarter wave length or odd multiple thereof. Grid bias may be provided for in a single resistance Rg.

In the arrangement of Fig. 7, which shows two tubes according to Fig. 6 arranged back to back, circuit symmetry is not necessary in order to obtain the highest frequencies of oscillation or to assure optimum stability. In this arrangement power may be doubled and the capacitatve coupling C of the structures of Figs. 4, or 54-50 of the structure of Fig. 6 diminished-an effect which substantially reduces danger of flash over at high voltage.

In another preferred form, double-tube 'circuits such as those shown by way of example in Figs. 8 and 9 may be employed. In Fig. 8, which represents schematically two tubes I and I having grids directly connected symmetrically with respect to earth and through common resistance Rg, the two anodes are at opposite ends of the structure and electrically connected to the extended cylindrical conductor 6D coaxial with the structures of the two tubes it surrounds. This cylinder may be provided with orifices 6| appropriately located to permit passage of a lead-in connection 62 to parallel filaments, these connections 62 preferably being in the form of transmission lines adjustably suppliable from a source 63 from points adjustably intermediate short circuit members 64. These intermediate points may be grounded through resistances 65. Such an arrangement represents a complete electrical circuit, one that is symmetrical, and one in which the connection impedances are reduced to a minimum as a result of the conductive envelope 60 being like a coaxial line and also as a result of the grid connection.

Fig. 9 represents an arrangement of two tubes having external anodes connected in a circuit similar to that of Fig. 8. The structure of these tubes is preferably such that the grid connections comprise a conductor coaxial with the conductive envelope 60, the length of which has been predetermined for the desired frequency of operation. It will be seen that the anodes of the tubes may project externally of the closed circuit and that they have practically no influence upon operation of the circuit, in other words, their dimensions are such as to have no effect on the oscillating circuit dimensions. This permits the said anodes to be cooled by any appropriate means. This arrangement then offers a preferred form of high power tube. Reference numerals in Fig. 9 are similar to those in Fig. 8. The grid connection may be made, as shown, by a conductive sleeve member 66 wired to the output conductor 61--61' of the grid. The filament supply is not shown in full, but may be analogous to that illustrate in Fig. 8.

Although external anode tubes have been shown in the embodiments illustrated in the drawings, it is apparent that the invention may equally well be applied in c-ases in which the tube envelope completely surrounds the tube elements; and an internal anode such as, for example, in tubes having an opposed grid and plate. Moreover, it is also applicable to multi-electrode tubes other than triodes.

For illustrative purposes, the invention has been described particularly in connection with the familiar Colpitts oscillator of Fig. 1. It is to be understood, of course, as not being limited thereto since features of the invention may be adapted to other known oscillator circuits, for example, those of the Hartley, tuned grid and plate, ultra-audion, dynatron, Meissner, etc., tynes. l

What is claimed is:

l. An electron discharge device including coaxial electrode means including cathode means,

grid means, and anode means, an envelope of insulating material sealingly surrounding said elec.. trode means, electrodes of said electrode means being formed with coaxial portions extending externally of said envelope, and generally cylindrical resonator means coaxial with said electrode means, said resonator means including means capacitatively coupling said electrodes of said grid and anode electrode means together.

2. An electron discharge device comprising a cathode, a generally cylindrical control grid substantially coaxial with said cathode, a generally cylindrical anode extending coaxially about said grid and said cathode, said grid being formed with a flared portion integrally and coaxially throughout and extending radially outwardly, said anode also being formed with a flared annular portion integrally and coaxially throughout and extending radially outwardly, capacitative coupling means between both said flared portions, and means forming an envelope sealing olf said cathode, said grid, and said anode.

3, An electron discharge device comprising concentric electrode means including two coaxial electrodes, an envelope sealed about said electrodes, one of said electrodes being formed with a flared generally coaxial annular portion extending radially outwardly from one end of said one of said electrodes, the other of said electrodes being formed with a ared generally coaxial annular portion extending radially outwardly through said envelope from the end of said other electrode opposite said first-mentioned flared portion, and coaxial coupling means between said flared portions.

4. An electron discharge device comprising electrode means including a cathode, a grid coaxial therewith, and an anode surrounding said cathode and said grid and coaxial therewith, an envelope sealingly surrounding said electrode means, said grid being formed with a coaxial portion extending externally of one end of said envelope, said anode being formed with a coaxial portion extending externally of the` other.

end oisaid envelope, agenerally cup-shaped co1 axial member ccnductively connected tosaid ex.-` tended portion of said anode, ,a generally. cupf` shaped coaxial member conductively connected to said extended portion of said grid, the-peripheral edgesof said cup-shaped membersbe= ing formed with integral annular flangedgportionsspaced from each other and forming areapacitativel coupling therebetween, ,and capacita-r tive output couplingr means on each of said 'cupshaped members.

5. An electron discharge device having ,elec-1 trodes including (coaxial control. grid and anode means, an envelope of insulating materiall sealingly surrounding said electrodes, said control grid and said anode means beingformedg with coaxial portions extending generally longitudinall-y and externally o said envelope, and/.gen-V erally cylindrical resonator means coaxial with said electrode means, said. resonator means including means capacitatively coupling said con.- trol grid and said anode means together.

6.*An electron discharge device comprising a sealed envelope of insulating material, an anode element consisting of a cylindrical conducting member having one end projecting within said envelope, said end having a hollow cylindrical.

cavity, cathode and grid elements mounted within said cavity, said grid element having a portion extending outwardly of said envelope, and means outside of said envelope forming a capacitative coupling between said grid and anode elements,

said means including a shell mounted outside of and about said envelope, conductively connected to that portion of one of said elements. outside of the envelope and capacitatively related to. that portion of the other of said elements outside. of

said envelope.

"7. 'Ihe combination according to claim 6,.- which said shell is connected tothe portionvof. the grid element outside of said envelope. l

8. The combination according to claim 6.in which said shell is connected to that portion. vof the, grid element outside said envelope, and in which said last means includes a second shell connected to that portion oi the. anode elementA outside of `said envelope, said shells being co axial and spaced from one another in the longitudinal direction forming the capacitative coupling.

9. The combination according to claim 6, in which said one shell is formed as a hemispherical shell connected to that-portion of the grid ele- Y ment outside of said envelope, and in which said last means includes a second hemisphericalshelll connected to that portion of the anodev element outside of said envelope, said shells. being co.-

axial with one another and having their outer peripheries spaced from one another to form'the capacitative coupling.

llgrThe combination according to claim 6, in

which said one shell is formed as a hernispheric'al shell connected to that portion of the grid ele ment outside of said envelope, and in which-,said last means includes a second hemispherical shell connected to that portion of the anode elementv f outside of said envelope,` said shells being coaxial with one another and having their outer peripheries spaced from one another to form the capacitative coupling,l said hemispherical shells being` provided with venting open-ings'.

H11. The combination vaccording to claim',y inr which `said one shell is icrrmed'as ahemispherical shell connected tothataportion ofthe grid ele-x mentv outside-of saidy envelope; and iniwhich said last ymeans includes av secondhemispherical shell connected to that'.f portion ofthe anode element outside `ofvsaigl envelope, said shells benigno-axial witl'rone anotherY and lhavingtheir outer peiripl'ieriesl spaced, from4 one another .to forni the capaeitatifve. coupling, said last `means also including-.a conducting: connected to said: grid element outside' of said` enveiope-y and aftubtdar member formed as an integral'extension of saidk second. shell rigidi-y arid'conductiveiy supported in said conducting tube'.

12. The combination according .tot claim yin which said one shell is formed as a hemispheric'al shell,cor-mectecl` to that portion of -the grid 'ele'.- ment outside'of said envelope, and in which said last means includesv a second-j hemisphericalV shell connected. to that portieri` ofthe; anode element outside ofY said envelope, lsaid lshells being co'` axialr with' oneV another and: havingctheir ',outer peripheriesspaced fromone'- another to form theA capacita-tive coupling, said' last means also in-i cluding a.A conducting tube connected to said grid element outside-of said envelope; and a tubular member formed as an integral extension ofl said secondv shell rigidly' and conductively supported drical anode element,r and. means' extending through. said envelope conductivelyconnecting said grid element-to-said shelif., a l v l14. rlhecombination. according., to claim 13, With a ground. positionedy adjacent.I theY open endE of:saf1d shell, and. inewhichfthedistance from the pointof: connection: ot said shell with said vgrid elementl Ito said' ground 'equals4 A 4. f

15.. The.V combination according to claimA 13,y

with a ground. positioned adjacentthe open end` of said shelLj. and an. annularwange attachedv tov the open end of said shelll adjacent saidf ground,

andinwhich theydistance from-.the point-of con. nection. or .said shell'with saidig-ri'd to saidground` equals/AY.- H d d Y Y. 16:.The combination-iaccording to claim 13,

`with a ground positioned adjacentthe open end of` said shell, ariy annularflange, attachedy to the open endivofisaid shelliadjacent said, ground, andv an annular flat flange. attached. to 'said cylindrical` anode element outside ofsaidfenvelopo; the dis.-

tance from the pointy-ofi connection of said shell with. said.- grid totA saidfground and the distancey from; said at; flange. Yto theI closedendof said shell i each being. equal toy M4.

Gmn/erizol PAUL CHEVIGNY.

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