US2433380A - Amplifying arrangement - Google Patents

Description

A. J. MADDOCK AMPLIFYING ARRANGEMENT Dec. 30, 1947.

Filed June 1.2, 1945 cks a yV W M, 7 7 M,

Patented Dec. 30, 1947 f'Alan Julian ll'laddock,` London,

England, assignon Vby mesne assignments, to International Standard Electric `(lorporation, corporation of Delaware New York, N. Y., -a

Application June 1 2, 11943,Serigl No.1'490,'5851 l In Great Britain July 3, 1942 Claims.

'The -`present invention vrelates Ito amplifying `arrangeiner-1t's `and vparticularl'y` to 'amplifying system feeding two or more loads, such fas antennae, with currents having diierent relative phases.

With directive antenna systems in which two or more antennae are to be fed with current of different relative Aphases :it is usually essential that the magnitudes and phases of the currents should not vary with respect -to one another due to variations in amplifier characteristics. These conditions are particularly important, for example, in systems used for guidance of aircraft, ships, etc., where two lover-lapping eld strength patterns are used Jvcapable ofheing radiated :in seme 4rhyitmn'ic manner sb that on each side of the line Yjoining the intersection 'ofthe two patterns and the centre fof theV antenna system a different and `distinctive .signal iis radiated whilst -on the intersecting line a continuous signal is obtained; this is produced for example by radiating one pattern for the period of Va dash land the/other pattern 'for the period lof a fdot, the `two following each other regularly.

Under such circumstances -i-t yispre'ferable that all antennae 'should "be #energised by the same amplier system to -bbviate any ldifference of phase or magnitudearising between the antennae which might occur 'if separate jam'p'liiiers'are used. In many instances it is 'possible to 'do this but for som-e applications heretoforefit hasbee'n found necessary to use separate 'amplifiers 4with the above mentionedjdiculties arising thereby.v It is the purpose -of-this "invention to provide a systern whereby the antennae are energised by the same amplifier thus `Aleading te 'elimination of effects arising from variations of magnification in the valves of the -ampaflen variations of grid driving volts, variations Iol high tension anode supply, etc. The scheme will be "considered with particular reference -to an approach system having three driven or lerie'nglised antennae, the currents in which diner in v'phase `and magnitude and it will fbe shown herinaiter how characteristic changesY ofthe "adiated pattern may be effected in simple manner whilst still retaining all the above advantages.

Accrding to 'the invention an electronic discharge device-amplifying system arranged to feed power inte tw-0 n die loads fis charaeterisei in this that it "coin 'es two amplifying arrangemerits fed'from the saine vsource fin push-pull and parallel linode'sA with 'any desired amount 'of phase dinerene'e vbetweein 'the Adriving voltages for the two 'modes'. vand thatme lead circuits are so coupled to the output circuits nf 1the two ampliplifier circuits.

Referring to Fig. '1, A and rB are thermionic 'amplifying valves `each having grid input and anode output circuits resonant yto the frequency of operation, the `circuits 'of the valves being `dis posed relative to ea'ch other so as to have negligible reaction between each other. '(The sources of supply for cathode and grid are not shown as not being relevant to the 'invention and thesemay be arranged in any known manner.) 'The three valves X, Y and Z have their grid inputcircuits connected in parallel and excited from the common source of radio frequency as shown. The valve Z has a phase 'shifting network yK inserted in its fg'rid circuit so that the phase of the voltage applied to its `grid relative to that applied 'to X or Ymay beset to la-fdesired value.

Onlyone of 'thevalv'es X or Y is permitted to amplify at vvatiine, the grids o'f these valves being connected to sources of large negative value via 'a keying system connected at GKS, and any sultable keying system may be employed, but a .particularly 'suitable arrangement is disclosed in `my British Patent Number 558.224 of March 2l). 1944, so that keying may be eiie'cte'd in complementary fashion with instantaneous 'changeover between the two values. 'I-'hus when valve X is amplifying say for the period of a da'Sh, Y is blocked and then Y amplies for the period of a dot and X is blocked and so on. A'push-'pull circuit is connected Yto the outputs of valves X and'Y and lconsists of the coils L1 and condensers`C1, the centre point of which latter is returned to the valve cathodes and the coi-ls L1 are so 'connected as to be series aiding for the push-pull voltage, thus driving the valves -A and B in push-pull through the intermediary v'of the coupling-existing between coils L1 and La. The 'anode utuned circuit LiCi is excited from either side alternately at the points :t and y by the valves X and Y, respectively, by means of the complementary keying arrangements referred to and connected at CKS, and 'thus a phase change of 180 may vbe obtained in the push-pull driving volts applied tothe grids of vA Vand B as desired yby the keying rhythm. Y

At the same time :as A and B are driven in push-pull mode they are also driven in the parallel mode at the same frequency by the valve Z having output circuit LzCz, the coils Lz being so connected and coupled to coils L3 that the grids of A and B are driven in parallel. The phase difference between the parallel and pushpull voltages is The valves A and B will thus have a resultant voltage equal to the vector sum of the push-pull and parallel voltages applied to their grids and will amplify same and develop corresponding voltages in the output circuitsfCiA, L1A and Cna, Lne. By connecting coils Ls-tuned by con-V densers Cs-in such sense as to be series aiding for the push-pull voltages in Lui and L43 only such voltage and hence such power will bedelivered to antennae P and Q whilst coils La (tuned by condenser Ce) are connected in such sense as to be series aiding for the parallel voltages in L4A and Ln; so that only such voltage, and hence such power, is delivered to antenna C. With the arrangement as shown, the currents fed to the two antennae P and Q will differ by 180 and that fed to C will differ from that fed to one antenna of P or Q by the amount of phase shift introduced 'at K and by 180 minus this shift from the other of P or Q; as X and Y are keyed the phases of the two antennae P and Q will be changed by 180 as already described.

Thus with this arrangement the power fed to all antennae is supplied by the same amplifier system (viz. A and B) so that any variation of anode supply or variations in valves affect all antennae equally and hence do not cause relative changes in the radiated eld patterns but only changes of magnitude which are unimportant.

The amplifiers X, Y, Z, A and B may be operated under any condition but in a preferred arrangement they would all operate as Class C ampliers (it will be shown Vbelow that Class C operation is possible) since then variations of grid drive will not affect the output and thus even if valves X and Y did induce different voltages on the grids of A and B the output in the two cases would still be the same. For the same reason any variation in Z would not cause changes in the relative outputs. Preferably, also valves X, Y and Z would have the same source of anode tension suppy so that variations are still further reduced. If the Valves are operating under Class A or Class B conditions, the radio frequency input may be modulated if required or with the preferred Class C working valves A and B may be anode modulated.

Relative phase changes between P, Q and C other than those automatically obtained above may be introduced if desired by variation of length of the transmission lines feeding the antennae or by the introduction of phase shifting networks in the feed to said antennae in manner well known in the art.

In Fig. 2 in which ordinates represent amplitude and abscissae represent electrical degrees, the push-pull voltages induced in the grid circuits of A and B are shown at P-P Voltage of A or of B and the parallel voltage applied to A and B simultaneously is shown at parallel voltage of A and B of amplitude equal to the push-pull voltage and diiering in phase therefrom by 90 and +90 respectively. The resultant voltages applied to the grids of A and B are as shown at resultant voltage of A or B in the heavy lfull and dashed lines respectively andthe anode voltages in the output circuits L4. Cia, L43 C413 determined by the network Y Vtion, from the output 4 would be correspondingly similar and it can readily be seen that since these voltages were built up by injecting two voltages in push-pull and parallel and differing in phase as hereinbefore stated, they may be separated utilising push-pull and parallel circuits after amplicacircuits of valves A and B.

- It is known that if two sine waves of the same vfrequency and any relative amplitude and phase are combined the resulting wave is also a sine w`ave:"y ifY e sin wt represents one wave and e1 sin (wt-gbl the other where e and e1 are the amplitudes, a the angular frequency, t the time and p the phase difference between the two waves; then it can be shown that the resultant wave is represented by which, since all factorsl except wt are constant, is of sine wave form. In the special case when e=e1 this reduces to Eu=2e cos .1s/2. sin (wr-qq2) (a) and in the further special case when =1r/2 (and e=e1), Equation 2 or 3 reduce to MFM/. sin (wt-WM.) (4) In the arrangements of the present invention the output voltages of 'valves AV and B must simulate those applied to their grids so that the resultants may be analysed into their components and this may readily be done if A and B work under Class A or B conditions. In Class C operation, even a distorted input voltage will give a sine wave voltage in the output so that normally this type of ampliiier is not used to follow variationsv of grid circuit voltage. However, since, as we have shown, the grid input voltage in these arrangements is always of sine wave form we may utilise this class of operation and so obtain output voltages following the grid voltages.

With the special case considered of a phase shift being introduced at K (Fig. 1) of 90 we are able to feed an antenna system very suitable for use in guiding or approach systems wherein a centre antenna is fed with current of constant magnitude and two outer antennae are fed with currents displaced and '+90 with respect to the centre antenna and these outer currents can be instantaneously changed in phase by to obtain the required change of eld pattern. The relative magnitudes of the currents can be altered by variation of the coupling between L5 and L4 or between La and L4. Y

There is no interaction between the parallel and push-pull circuits when arranged as described, for the voltage induced in say one parallel coil (L2 top) by the neighbouring push-pull coil (L1 top) will be annulled by an equal voltage induced in the bottom L2 coil due to the way in which the coils are connected and similarly interaction in the opposite sense is annulled.

The foregoing description has detailed the case of an antenna system in which instantaneous keying is required but it is clear that the system is equally applicable to systems in which constant radiation is to be emitted and it is readily evident that any number of antennae greater than one, may be fed in this manner in which case one of the valves X or Y may be omitted. For example for two antennae one is fed by the parallel coils L6 and the other by the push-pull coils L in which case the condenser C5 need not be split. For three antennae the scheme already described may be employed if two of the antennae are to differ in phase by 180 or as mentioned subsequent phasing networks or lines may be inserted. Four antennae may be similarly driven arranged for example in pairs, the coils L5 driving one pair and coils Ls another pair. And so on, variations in the arrangements described being readily apparent to those skilled in the art and coming within the scope of the invention as defined in the appended claims.

Similar keying arrangements may be provided if desired for the parallel drive in which case a split driving circuit Vwould be provided for this mode and two valves instead of the one Z with a similar arrangement of keying as already described for X and Y. Both the parallel and push-pull driving keyed circuits may be provided together.

Whilst the phasing network K has been shown in the grid circuit of valve Z it may equally well be inserted in the anode circuit thereof. It is an added advantage of the scheme that phasing of the antenna currents may be effected in low power circuits where control is readily possible.

Although reference has been made throughout to the power being delivered to an antenna system this is not meant to imply a limitation on the invention since any load may be employed and furthermore the invention is applicable to arrangements using other frequencies than radio frequencies.

What is claimed is:

1. An amplifying system employing electron discharge devices and adapted to feed power into a plurality of load circuits comprising a pair of valves having input and output circuits, a source of high frequency voltage, means to feed voltages from said source to the input circuits of said valves in push-pull and parallel modes with predetermined phase displacement between the voltages of said modes, a plurality of load circuits, means to couple one of said load circuits to the output circuits of said valves so as to transfer power in one mode, and means to couple another load circuit to said output circuits so as to transfer power in said other mode.

2. An amplifying system in accordance with claim 1 in which the feeding means for the input circuits of the valves includes a phase adjustment device so that the phase between the two modes may be adjusted.

3. An amplifying system in accordance with claim 1 in which separate amplifying devices are provided to feed the input circuits of the valves in the different modes.

4. An amplifying system in accordance with claim 1 in which the phase difference between the push-pull and parallel modes is substantially ninety electrical degrees.

5. An amplifying system adapted to feed power into a plurality of load circuits comprising a first pair of valves having input and output circuits, a source of high frequency voltage, a second pair of valves having input and output circuits, means to connect said second pair of valves in push-pull, means to couple the input circuits of said second pair of valves inpush-pull arrangement with said first pair of valves, a source of high frequency voltage, means to feed high frequency voltage from said source to the input circuits of said rst pair of valves in parallel and with the phase of said voltage displaced a predetermined amount from that fed to said second pair of valves, a plurality of load circuits, means to couple one of said load circuits to said output circuits of said first pair of valves so as to transfer power to said load circuit in the push-pull mode, and means to couple another of said load circuits to said output circuits for said first pair of valves so as to transfer power to saidload circuit in the parallel mode.

6. An amplifying system in accordance with claim 5 in which means is provided to adjust the v relative phase of the voltages delivered from the claim 5 in which source of high frequency voltage to the input circuits of said rst and second pair of valves.

7. An amplifying system in accordance with claim 5 in which a separate amplifier is provided between the source of high frequency voltage and the means to feed the voltage to the input circuits of the first pair of valves in the parallel mode.

8. An amplifying system in accordance with claim 5 in which a separate amplier is provided connected between the source of high frequency voltage and the means to feed the input circuits of the first pair of valves in the parallel mode, and a phase adjusting device is included in this feeding circuit.

9. An amplifying system in accordance with means is provided to block the valves of the second pair alternately at a predetermined rate.

10. An amplifying system adapted to feed power into a plurality of load circuits comprising a rst pair of valves having input and output circuits, a second pair of valves having input and output circuits with said input circuits connected in push-pull arrangement with the output circuits of said first pair of valves, a source of high frequency voltage, means to connect said source to the input circuits of said first pair of valves in push-pull arrangement, a fifth valve having an input and an output circuit, means to connect the input circuit of said fifth valve to said source of high frequency voltage, means to connect the input of said fifth valve in parallel with the input circuits of said first pair of valves, means to adjust the phase of the voltage delivered in parallel to the input circuits of said first pair of valves, a plurality of load circuits, means to connect one of said load circuits to the output circuits of said rst pair of valves in push-pull, and means to connect another of said load circuits to the output circuits of said first pair of valves in parallel.

ALAN JULIAN MADDOCK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,211,942 White Aug. 20, 1940 2,332,253 Peterson Oct. 19, 1943 1,666,738 Hartley Apr. 17, 1928 1,773,116 Potter Aug. 19, 1930 1,831,516 Stewart Nov. 10, 1931 1,882,119 Chireix Oct. 11, 1932 2,212,230 Goldmann Aug. 20, 1940 1,910,427 Diamond May 23, 1933 2,203,004 West June 4, 1940

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