US2483189A - Transmission line oscillator - Google Patents

Description

Sept. 27, 1949. c. c. EAGLESFIELD 2,483,189

TRANSMISSION LINE OSCILLATOR Filed Nov. 28, 1945 W8 CECIL EAGLFSEZELD.

. I N VEN TOR.

BY p I ATTORNEY.

Patented Sept. 27, 1949 TRANSMISSION LINE OSCILLATOR Charles C. Eaglesfield, Bournemouth, England, assignor to The Hartford National Bank & Trust Company, Hartford, Conn., trustee Application November 28, 1945, Serial No. 631,349 In Great Britain September 13, 71944 Section 1, Public Law 690, August 8, 1946 Patent expires September 13, 1964 7 Claims. (Cl. 250-36) The present invention relates to electric oscillator circuits particularly for use at ultrahigh frequencies in which the oscillations produced have their frequency determined wholly or partly by transmission line systems.

One known circuit arrangement of this type uses a triode valve, or a valve connected to operate as a triode, with the anode and grid convarying the effective length of the two-conductor transmission line. The intensity of oscillation may be adjusted by varying the effective length of the single-conductor transmission line.

The object of the present invention is to increase the frequency range obtained with adjustment of the effective length of the two-conductor transmission line for a fixed setting of the effective length of the single-conductor transmission line.

According to the invention the two conductors of the two-conductor transmission line are arranged to be electrically unbalanced with respect to the conducting sheath enclosing them. This result may be achieved either by geometrical asymmetry, in that for example the two conductors have unequal cross-sections and/or are disposed asymmetrically with respect to the conducting sheath enclosing them, or by purely electrical asymmetry, or by a combination of both.

As an example of electrical asymmetry, in an arrangement in which adjustment of frequency of the oscillator circuit is achieved by having two ganged variable condensers or inductors connected each between the conductingsheath of the two-conductor transmission line and a point on one of the two conductors, so that the effective length of the said transmission line may be varied, the two variable condensers or inductors are electrically unequal.

In another form of the invention a condenser or inductor having appreciable reactance at the frequency of operation of the circuit is inserted between one of the said two conductors and the corresponding electrode of the triode valve.

'way of inductance M to anode 3.

In order that the invention may be better understood, reference will now be made to the accompanying drawing in which: 7

Fig. 1 shows a circuit arrangement including a reactance between one of the conductors and the anode Fig. 2 shows a circuit arrangement including ganged variable condensers between the two conductors and the conducting sheath.

Referring first to Fig. 1, the triode valve referred to above is shown by I, its grid, anode and cathode being denoted by 2, 3 and 4 respectively. The grid is joined to a grid leak 5 and condenser E which serve to produce automatic bias when the triode is generating oscillations. Condenser 6 will have negligible reactance at the oscillation frequency. A two-conductor transmission line has. two conductors 1, 8 arranged preferably symmetrically with respect to a conducting sheath'9. Conductor 1 is joined to the condenser E as shown while conductor 8 is connected by The cathode 4 is joined to the single conductor it contained in conducting sheath [2. sheaths 9 and [2 are connected together as shown schematically by lead 15. Conducting bridge l0 controls the effective length of the two-conductor line 1, 3 and therefore the operating frequency of the oscillator circuit. Bridge 10 in this example should not contact with sheath 9. A positive potential may be applied to the anode 3 at the end E6 of conductor 8. Conducting bridge 53 across the conductor H and sheath 12 controls by its position in known manner the intensity at which the circuit oscillates. The negative pole of the source providing the above-mentioned positive potential is connected to sheath I2 as shown.

The inductor M is arranged to have appreciable reactance at the operating frequency of the oscillator circuit with the object of providing the unbalance of the two-conductor transmission line I, 8 referred to earlier which constitutes the present invention. The value of this inductance is best obtained by experiment.

Using the circuit described above with reference to Fig. 1, it has been found that a larger frequency range may be covered by adjustment of bridge [0 for a given fixed position of bridge it without the oscillator ceasing to oscillate, or

is high at the operating frequency, e. g. a radioirequency choke, is provided in the positive lead to the anode but not between the anode 3 and the conductor; 8.

In the circuit of Fig. 3, a transmission line electrically unbalanced with respect to the sheath is obtained by disposing conductors l and 8 of like diameter asymmetrically with.respecttosheath 9. The circuit is otherwise identical With'that of Fig. 1 except that inductor- M is omitted.

I claim: 1. An oscillation generator --circuit arrangement comprising an electron discharge device- :ing in an electrically unbalanced,relationship with respectto said sheath, and a single-conduc- Itor transmissionlinecomprisinga conductor cou- .pled to said cathode and a second sheath surrounding said third conductor and coupled to.

said first sheath.

'2. An oscillation generator circuit arrangement comprising an electron discharge device having a cathode, a grid and ananode, means to. apply operating potentials to said discharge device, a twoconduotor transmission -line comprising a .first conductor coupled to said anode,.asecond conductor coupled to said grid and a sheath surrounding said conductors, said conductors ibeing in an; electrically unbalancedrelationship with respect to said sheath, a single-conductortransmission line comprising aconductor coupled to said cathode and-a second sheath surroundin said third conductor .and coupled to said first sheath,-and means to adjust theeffective length of the conductors-of said twoconductor transmission line to adjust theirequencyoflthe oscillation generator.

3. An oscillation generator circuit arrangement comprising an electron dischargedevice havin a cathode, a grid'and ananode, means to apply operatingpotentialsto said discharge device, a two-conductor transmission line .comprising a first conduotor coupled to-said anode, a second conductor coupled to saidgrid and a sheath surrounding said conductors, said conductors having identical diameters and one conductor bein spaced at a greater distance from the sheath than the other conductor to produce an electrically unbalanced relationship with respect to said sheath, a single conductor. transmission line comprising a conductorcoupledto said cathode and a second sheath surrounding said third conductor-and coupled to said first sheath, and means to adjust the efiective length of the conductors of said two-conductor tr-ansmissionline toadjust the frequency of the oscillation generator.

4. An oscillation generator circuit arrangement comprising an electron discharge device having a Ca/thd,;j2. gridand an anode, means to apply operating potentialstosaid discharge device, a-tWo-conductor transmission line comprising a first conductor coupled tosaidanode, a sec- 0nd conductor coupled to said gridsand a sheath surrounding said conductors, variable reactor connected between said firstconductor and said sheath, a .second variable reactor connected between said second conductorand said sheath, one of said reactors having a value greater thanthat ,of the. otherof saidreactors and said reactors being mechanically coupled to ether to maintain said conductors in an electrically unbalanced relationship with respect to said sheath, and a single-conductor transmission line comprising a -=third conductor. coupled said cathode and a .second sheath surrounding said third-conductor and coupled to said first sheath. 5. An oscillation generator circuit arrangement .cornprising. electron discharge device havin a cathode, a grid and an anode, means to apply I -mperatingLpotentiaIS to said discharge device, a

twoi-conductor transmission line comprising a :first conductor coupled to said anode, a second conductor coupled to said grid and a sheath surrounding,;. said conductors, a variable capacitor connected between said first conductor and said jsheatna-second variable capacitor connected between said second conductor and said sheath, one of said capacitors having a value greater than that of the other of said capacitors and said camacit being me a cal y. c upl to et e maintain said -conductors; in an electrically .balanced,relationshipmith respectto said shea and a singleeconductor transmission line compr s n a th rd con ctorw p e t idcath- .Qdeand a second .fiheath ,surrounding said third on uct an .coupledt aidfi t sh th- 6- An osci l tio generatorpircn tarran eme comprisin an electron d s harg .i evice ar n .a.-cath d ,,.a g i and a ano m a s to a ply o ratin Po n ia s o sai d scha ee v efi, a

tw r ond to ansmis ion .,,l c m is n a f rst conductor coupledto said ,anode, a second ,conductor ooupledto said grid and a sheathsurm gin aid conductor a react int pos hetwefi said .fiIf .0Ql1i i ;Q '-fl said ano i .mai tain. said conductor an e ri all i 1 balance re atig s i i r p c to heath. .a ing wondscto :an$mi. i0 .li q rr sins .a con uct .c ll l it ald eth d an a e on 40 sheaihfs rm n n sa cih r con an cou led. osa d. fi s she an m n to diu theefle v le t of h duc r v sa d tw i end ebo tra l m ssion in ad u t f q n yo th psci-atio genera r- 7-. en osq ll tioasensra o c c a a em icqnnir ins a ele tron. discha d c h in saihn aa daedananed m a t am q erafi roientia & s id s a i d ic tw wnducie .i 'ans issie l w e s n a first conduct-or coupled to said anode, a second -eo deeie s r led .t said i a d ashe i r nd n s i cond c o a in uc o interposed betweensaidfirst conductor and said anode to rnaintainsaid conductors inanelectrically unalanced relationship with respect tosaid sheath,

alsingleconductor transmission line comprising a conductorcoupled to said cathode anda second sh eaith surroundingsaid third conductor and 9 1 1 i re st heath. a me n t d u the eilectivelength er,theconductors of said two- .e a uci tra smis i n lin t adjust t quen ti e illa ie ene wr- A LES E G SE L nsrnnnncns crrno {The following vreferences;are of record in the ,file of this patent:

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