US2011299A - High frequency apparatus - Google Patents

Description

Aug. 13, 1935." H. s. POLIN I 2,011,299

HIGHFREQUENCY APPARATUS Filed Dec. 28, 1932 A Pg M "IE i 3mg]? 75 Powerjaw're 75 7% 0' Jawre 4 j G j'lf A I a 7 INVENTOR Herder! j E/flz Patented Aug. 13, 1935 Hr. 2,011,299,,1 f f incn FREQUENCY APPARATUS Herbert Spencer Polin, Port'Washington, N. Y'.,

1 gassignor to Polin, Inc., New York, N. Y., a corporation of Delaware i f I H Application December 28, 1932, Serial N e ialeo l Claiml (aria- 3m mew Thistinvention relates to electronic apparatus ion the production of extremely short electromagnetic wavesjand'to signaling systems embodying such apparatus.

contains fa' blo cking element I2; and the primary of a transformer T2, the secondary of which is connected-to a signal indicating device R; such asa pair of phones. Blocking elements I3 iso- Attempts have been made to produce short wave late athigh frequency, the cathode K from the oscillations by arranging an electronic tubeto potential supply source. f oscillate through its internal or inherent inter- Connected directly between grid G and plate "P, "electrode capacitiespOne means that has been is an extremely small variable condenser D utilized is to provide b etween grid and anode For purposes of withdrawing oscillatory energy electrodes an inductive connection of extremely from or impressing oscillatory energy upon th 1 Small inductance ifal Such as SP V by system, there is provided a tri-plate condenser i sectifm flu w l n u th b. t D2 having an intermediate stator plate connecte experimen as in epas ,mew1 u r v dubious success. Production of oscillations has E ;Z 12 32 1:g 3Z2; fiiigffiz fia g aifi i ifi 1:22;: stag er-[irritate a resist: P: D1 D2 of a 15 cillators constructed o'f apparentlyidentical parts, pfrmlttmg Pqjlcmmetnc adltlstmenls R 2 i some oscillate 'wli ilaothers donot. No explanap ca'pacltles' The platesgother than the tion has heretofore been advanced as to the mediate stator plate, are preierably annular, with 0 read-Sons for this; hlnygcertam remedy been tle plate separations ad ustable by screw thread-' proposed, e means, 7

As a result of theoretical studies, backed by ex-- Th system f F 1 Will up n p p r ediustperimentf culminating-"in the present invention; ment of the circuit elements indicated as vari- I am convinced that the difliculties experienced able, generate sustained oscillations of extremeby earlier investigators have resulted from their 1y .high frequency. Operation thereafter to 25 failure to understand and hence Properly safisfy transmit and receive signals is'apparent from the l criteria goifielning the P P W of l d drawing. "On transmitting the amplitude-of high c111at10ns W P90111121 9 the type 0f frequency oscillations produced by tube V, is W fl q- 1 I I varied in correspondence with modulating poten- 30 It IS .pnmary the mven n tials applied to grid Gdue, to activation of deto enunciate these criteria to the end that those M D t f d 1 t d a i skilled in the art may with certainty and pre- Y e 2 me u e ves p ng oision, so arrange electronic apparatus of the mg Q t AJSFfFected thmugh q ew character referredto as to assure generation in of h t b? he a e a the mdu1atmg 9 3 a reproduoiblemanner," of sustained oscillations 'f w mfilcatefl by devlce having a desired amplitude and frequency, Limiting consideration to those portions only A further object of the invention is to disclose 0 e g- 1 cu r pon for the generation a high frequency,40r shortwave, oscillation system of sustained oscillations, the circuit may,'at the i adjustableto meet the condition'swhich are dis oscillation frequency, be represented as shown 40 closed herein as being requisite to sustained os diagrammatically .in" Fig. 2. At this frequency 40 cillation. N there'is effectively betweemgrid and plate elecn t e .d trodes afsmall inductance-L series with resist- Fig 1 shows a'short Wave communicgtiqh W ance R.- C2 is the interelectrode cap acity between temembodymg an q l i hr e m r a grid and anode of the tubejwhile C1 and C3 are 4 cordance with the present 1nvent1 0n.- the effective capacities occurring between grid 2 1S q m i t p and cathode and between cathode and anode, 171011 of the Fig. 1 0113011113 WhlCll 1s essential to respectively oscillation reduction. p m

The circ it ofFig. 1V employs'anelectron tube f .t'eferrmg p w i V having an anode or plate P, a filament or cath- P d m between" l Q Q t 't gnd and 50 ode K, and a control electrode or grid G. The fi d ij q se t ed ir q T951330 tube is energized from suitable potential sources tlvely, a re en e br ihe Vector applied over conductorsl-dinclusive extending impedances Z1, Z2 and Z3, can be Shown that respectively to the grid,-cathode andanode. the following equality represents the necessary Grid conductor l includes a high frequency and sufiicient condition requisite to the produc- 55 blockingelement I1, and: the secondary of a transtion and maintenance of sustained oscillations: a former T1, the primary of which is connected to j V i a modulating element M, such as a microphone 224.23) transmitter, energized from the source connected v 0 to cathode conductors 23. Anode conductor 4 where g and [L are respectively the mutual con seen that Equation (1) is equivalent to a system 'of two equations determining the frequency f and the value of mutual conductance g at which oscillations can be maintained. It is obvious from the problem that the values for f and g thus derived from the fundamental equation must be real, positive quantities if oscillationsareto be sustained. Moreover, the value of the mutual conductance g required must not exceed the maximum mutual conductance gm of the tube.

Replacement of the generalized impedances of Equation .(1) by the specific inter-electrodeimpedances of Fig. 2 results, neglecting higher order terms in R, in the following expression-requisite to the maintenance of oscillations withthe circuit .of Fig. 2: a

where Rd denotes the dissipative component ofthe impedance Z2 at the oscillation frequency.

Examination of Equation (2) shows that under no circumstances. can the circuit of Fig. 2 be made to oscillate if the capacity ratio the tube. From Equation (2) We therefore derive the result, verified by experiment, and contrary to what has heretofore been understood, that oscil- 4 0 lations cannot be maintained with the Fig. 2 type of circuit, even for exceedingly large values of mutual conductance 9, unless the capacity ratio is less than the magnification factor [L of the tube. Further examination of Equation (2) reveals that for a tube of given constants the. maximum capacity ratio a Q C3 at which oscillations will be sustained depends upon the dissipative resistance of the inductive connection and upon the oscillation frequency. For a given tube, the relationship may for some purposes best be shown by the following inequality derived from Equation (2) I where K is a constant dependentupon' the internal capacities and mutual conductance of the tube, and f the oscillation frequency in cycles per second. In order therefore for the circuit to sustain oscillations, the capacity ratio must be less than the magnification factor [L of the tube by an amount which is proportional to the product of the resistance Rd and the square of the frequency.

From Equation (2) one derives the additional general conclusions that conditions favorable to efficient oscillation production are improved to the extent that the ratio of capacities C1 to C3 is decreased below And again that the limiting frequency of oscillation may be increased by increase of the maximum mutual conductance gm, by decrease of the dissipative resistance Rd, or by a combination of these several factors.

It has generally been thought that tubes best adapted to the production of extremely high frequencies are those wherein the interelectrode tube capacities have been made as small as possible. To this end tubes have been utilized wherein stray capacity effects, due to the tube base, etc., are minimized or eliminated as by removing the base, etc. In a sense this, as shown by Equation (2), is a step in the wrong direction since it fixes the ratio of the grid-to-cathode and anodeto-cathode capacities at a relatively high value,

a determined by the closer spacing between grid and cathode than that extant between anode and cathode. The present invention teaches that stray or auxiliary capacities are beneficial to sustained oscillation to the extent that they reduce the capacity ratio in question.

, Analysis of the Fig. 1 circuit has shown that for generated waves, say of the order of centimeters, the electronic current is appreciably in phase with the alternating components of the grid and plate voltage provided these voltages are not too small.

The adjustable condensers D1 and D2 serially included in the inductive connections between grid and anode, provide a means of making the effective inductance L, Fig. 2, as small as is necessary for production .of oscillations of a desired frequency. At the oscillation frequency f the effective inductance L is:

where L is the actual inductance between grid and plate, and D the effective capacity of condensers D.

Thus condensers D permit of adjusting the oscillation frequency as desired, within limits, while the selection of a proper capacity ratio assures maintenance of oscillations at that frequency.

I claim:

Device for generating and detecting short electric waves, comprising the combination with an electron tube having an anode, a cathode and a grid, of an inductive connection between said grid and anode, a condenser serially included in said inductive connection for adjusting the generated wave length, the interelectrode capacities between said grid and cathode and between said anode and cathode respectively, having a ratio sufficiently smaller than the magnification factor of said tube to assure the production of oscillations at said wave length, and a tri-plate condenser having its external plates connected respectively to said grid and anode, and its intermediate plate connected to wave radiating means;

HERBERT SPENCER POLIN.

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