US1784957A

US1784957A - Electric wave transmission system

Info

Publication number: US1784957A
Application number: US755612A
Authority: US
Inventors: Philander H Betts
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1924-12-13
Filing date: 1924-12-13
Publication date: 1930-12-16
Anticipated expiration: 1947-12-16
Also published as: FR608517A

Description

Dec. 16, 1930. P. H. sans 1,784,957

ELECTRIC WAVE TRANSMISSION SYSTEM ifi-led Dec. 13, 1924 The path between the cathode and anode may include a capacity for neutralizing the capacity of the tube. By virtue of this arrangement, the tube capacity will be balanced at all frequencies, as would not be the case if these impedances were not balanced, because the coupling betweenl these impedances is a function of frequency and inequality in the impedances would thus cause unbalance at certain frequencies. In addition the phase re` lations of currents in thebalanced pathsof the arrangement of the invention w1llrema1n constant with frequency.

" Fig. 3 represents another form of radio .re-

-ceiving system having a tuned coupling circuit with means for causing regeneration to take place in one tube of the sy-stem.

Lilie reference charactershave been used in the several figures of the drawings to indicate lilreV parts. V

In Fig.. 1, the radio receiving system in-V cludes a loopantenna 10, a high frequency amplifier 15, a detector 20, and a signal receiver 25. The high frequency amplifier 15 includes the space discharge tubes 16 and 17 arranged in tandem by means of a coupling circuit 18.. The space discharge tube 16 has an input circuit connected to its control electrode and cathode which includes one-half of the winding of loop antenna 10 in series with polarizing battery 9. The midpoint of the loop is connected to the cathode of tube 16 and one outer terminal is connected to the control electrode. The opposite terminal of the loop is connected to the anode of tube 16 by a path including the balancing condenser 11. The loop antenna 10 is arranged to be tuned by an adjustable condenser 12, which isconnected between its outer terminals.

The coupling circuit 18 comprises a closed tuned loop including in series, adjustable condenser 19, inductance 13, fixed condenser 14 and inductance 21. Inductances 13 and 21- may, if desired, be inductively coupled but this is entirely optional. The output circuit of tube 16, which is connected to its cathode and anode, includes a portion of the inducf.

tance 13 in series with space current battery 22.` The impedance of inductance 13 included in the output circuit of tube 16 is preferably of such value as to match the impedance of the tube. A portion of the inductance 21 having an impedance arranged to match the input impedance of tube 17 is connected to the control electrode and cathode of the tube in series with a polarizing battery 2a. A portion of inductance 13 equal to that portion of inductance 21 included in the controlelectrode circuit of tube 17 is connected to the anode of tube 17 by a path including a second condenser 23, arranged to balance the capacity between control electrode and anode of tube 17. The condenser 1a included inv -7 the coupling circuit 18 serves to block current from batteries 22 and 2li. Condenser 14 is of such capacity as to have a negligible effeet upon the frequency of resonance of circuit 18. Y

Y The portion of inductance '13 included in the output circuit of tube 16 will, in general, have an impedance less than the inductance of 21 included in the input circuit of tube 17, hence there is produced a step-up of voltage from the output'circuit to the input circuit.

The output circuit of tube 17 is coupledto the input circuit of detector tube 26 by a second tuned coupling circuit 27 comprising adjustableV condenser` 19 varranged in series with inductance 13', condenser 1a and inductance 21 ina closed loop. Inductances 13` and 21 are preferably free of any inductive coupling with

inductances

13 and 21. A suitable average potential is maintained upon the control electrode oftube 26 by a blocking condenser 27, shunted by a leak resistance 28. A receiving device 25- in series with a' source of space current 29, represented as a battery, is connected between the cathode and anode of tube 26.

No balancing condenser is provided for tube 26, since no danger of, oscillations being produced is present, because ofthe low impedance of the tube output circuit to high frequency waves.

When a carrier wave modulated in accordance with signals is impressed upon the loop antenna 10, corresponding waves are produced in the input circuit of tube 16, amplified by tube 16 and supplied from the output circuit of tube 16 to tube 17 by means of a coupling circuit 18.

It is to be particularly noted that the inably tuned to the mean of the band of frequencies that it is desired to receive. By including the

inductances

13 and 21 in the single resonant circuit 18, their individual resonance properties are merged into the single resonant characteristic of the tuned coupling circuit 18, hence undesired effects from the resonant characteristics of these inductances are prevented. By including in the input and output circuit respectively, of tubes 16 and 17 only such portions of the

inductances

13 and 21 as will match the impedance of the tubes, the voltage produced upon the tubes by waves in these circuits will be increased proved. Y l

The signal modulated waves supplied to andthe eliiciency of transfer of the waves from tube to tube will be correspondingly ,im-

tube 26 are detected and resulting waves of signal frequency are supplied to the receiving device 25.`

The system represented in Fig. 2 includes an open antenna 10 coupled to the input circuit of ahigh frequency amplifier 15, which is arrangedto'supply waves to the input cirj.y cuit of a detector 20, having a receiving de# denser 31, and primary winding of a variablev transformer 32. The secondary winding of transformer 32 is shunted by an adjustable condenser 33 and so forms a resonant circuit, which `is connected to the control electrode and cathode of tube 16', in seriesfwith ipolarizing battery 34. The-'output circuit of tube 16 is coupled; to theV input circuit' of tube 26l` by a tuned coupling circuit 35, which is similar to the corresponding circuit 18 of The receiving circuit shown in Fig. 2 includesa condenser 36 arranged Vto balance the inherent capacityof tube 16', independent of balance of the input circuit of the tube. This arrangement has'an added advantage in that the entire voltageacross the second.

ary winding of transformer 32 is applied to the control electrode of tube 16', whereas if the capacity of tube 16 were neutralized by a connection from the anode to its control 'A detector tube 37 has its input circuit cony nectedto the output circuit Yof tube 16 by a resonant coupling circuit 18. The output circuit of tube 37 is transformer coupled to the input circuit of a louT frequency amplifier 38, arranged to supply Waveste a signal receiver 25.

The circuit here shown -Vembodies features included in the circuits of both Figs. l and' 2. For example, the balancing condenser 36 is arranged to neutralize the capacity of tube 16, independently of balance of the input circuit of the tube as inFig. 2 and a portion of the inductance 13 such as to match the output impedance ofitube 16l is included in its outputcircuit as inFig.` 1. i Y f A blocking condenser'39 in the input circuit of tube 37, in cooperation witlra leak resistance 40, is provided inlorder to main tain a suitable average potential upon the control electrode of the tube..V rIhe output circuit of. tube 37 includes the primary winding of a lowfrequency transformer 41 which is shunted by a path including aby-pass con-V denserv 43 connected by means of'a switch 42;" The condenser 43 supplies a low impedance path for hiO'h frequency. Waves around the winding of transformer 41,. The transformer preferably offers a high impedance to high frequency waves. A common battery'44' supplies space current to` tubes 16, 37 z and38 'inr` parallel. This battery is shunted .bya lcondenser 45v which provides val low impedanceV path for high frequency waves.A The oaths' odes of tubes 16, 37 'and'38 are heatedinse-` ries by a common battery 46 arranged infse.

ries with .the adjustable resistance '47 kThe output circuit'of tube 37 iscoupled tothe input circuitof tube l38 bymeans of trans-l former 41.-

An adjustable condenserf48 arranged toj be connected between the anodes oftubes 16 and 37 by the operation ofv switch 42 which at the same time disconnects' condenser 43 viding a feed bacl; patli between'itsV output and input circuits to allow increased regen- By adjusting condenser-48v erative action. the proper amount of regeneration necessary to secure the maximum amplification with-` out the productionof parasitic oscillations may be obtained. The primary windingof transformer 41 is designed to have high impedance for high frequency waves in order that thesewaves may be caused to traverse the condenser 48 in preference to the winding of the ltransformer which is connected in parallel with the condensery between the anode and cathode of tube 37. p

The invention, Awhich has here been described in 'connection with certain specific embodiments, is not to be limited tothe specific arrangements disclosed but only as indicated by the scope of the appended claims.

What is claimed is:

of space dischargeftubes, means for supplying hiofh frequency waves to one tube'and means for coupling said tube to another tube comprising inductanceand capacity elements 1. ln a radioreceiving system, a plurality Y 2. In a highfrequency transmission sys? teni, a plurality of space vdischarge tubes, means fornoupling said tubes comprising capacityv elements. and inductance' elements formingy a single resonant circuit therewith and arranged to match the tube impedances to the impedances presented4 to said tubes by said resonant circuit'. v a

3'. In a space discharge tube system, a plurality ot space dischargetubes having input andoutput circuits,meansor coupling an output circuit to-an inputcircuitcomprising asingle resonant loop, inductance elements in said loop having portions only included in said coupled circuits, said portions respectively havingponts` at the same alternating current potential and also respectively having points at alternating current potentials opposite toy t. In aspacedischarge tube systenna plurality ot space dischargetubes, input and outthe." alternating current voltagel from theV cathode to theA anode` in said output circuit oppositein signtof the alternating current voltage trom-the cathode to another point on said input circuit, said meanscomprising a single resonant circuit, an impedance element included wholly in said resonant circuit and Aonly partially in one of sa-id first mentioned circuits.- f

,5. In al high-frequency transmission sys'- tem, a plurality ot space discharge tubes, input andoutput circuits for said'tubes, an impedance included partly in said output circuit, a second'V impedance included partly in said input circuit, and a resonant circuit including Aboth said impedances, the portions of said impedances included in sairdcircuits being such as to match the impedances of the respective tubes tothe impedances presented to said tubes by: said resonant circuit.

6.V Iny an electric wave transmission sys-- tem, aplurality of space dischargetubes each having an input and an output circuit, a highly selective resonant coupling circuit in cluding a plurality ot ind'ucta-nces anda Variable tuning condenser, oneV of said inductances being connected in an input circuit and another being included in an output circuit, and a source ot unidirectional plate voltage connected between said inductances, said inductances included in said circuits having mutual induction therebetween; t

7. In a radio receiving system, an antenna, a spacedischarge tube ampliiier having an inputcircuit coupled to said antenna, means for balancing the capacity of said tube independent ot bala-nce of said input circuit, a second space discharge tube and a resonant coupling circuit for said tubes including impedances arranged to produce a step-up ot voltage in sai-d system and to match the tube impedances to the impedances presented to said tubes by said resonant coupling circuit.

8. A high frequency amplifier including aplurality otjthermionic valves in cascade.

arrangement, eachvalvehaving a grid electrode and an anode, a` grld circuit` and an anode circuit,inductance means connected' in one anode circuit, said inductance means having two terminals at opposite sides-of a point thereon, one of said-:terminals being con# nected to the anode ot its respective-value,V

.-said point of said inductance means being connected through arhigh tension battery to.

jtheilament circuit,r the other of said termisaid anode and said control element to points on said Ycircuit at alternating potentials al-` ways opposite to eachother withv respectv to the potential ot said cathode, and means for causing apotential on said circuit to control voltage regeneration: in said-system.

10. A system comprising an electric discharge device'having a cathode and an anode, a non-oscillatory electric discharge device having a cathode and a discharge control element, a highly selective tuned loop circuit intercoupling said devices, said circuit including two inductance elements,` independ' ent direct current pathsrespectively includ.- ing said inductance elements and respective-V. ly connecting a pair of points at the direct current potentials of said cathode andsaid. anode of said first device and a pair of points at the Adirect current potentials of said cathode and said control element of 'said sec-` ond device, a source ot space current fork said first device included inone of said paths, a circuit comprising means for energizing lsaid cathode otsaid iirst device, means for maintaining a point on said space current source at the same alternating current potential as avpoint on. said cathode energizing circuit, and a condenser connected between a point on said circuit and a point on oneo t said devices tor reducing regenerative action in said system.

l1. A system comprisingelectric discharge devices, a-,single resonant circuit intercoupling saidjdevices and, presenting different impedances to said devices respectively, one ot said devices having anode and discharge control elements, and a condenser connecting one ot said elements to a p'oint'on said circuit at a potential equal in value but oppositein sign to that ofV said other element.

In witness whereof, IV hereunto subscribe my name'this 11th day ot'December, A. I).

- PHILANDER I-I. BETTS.

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