US2406735A - Multisignal radiating system - Google Patents

Description

`Sept. 3, 1946. A. ALFORD MULTISIGNAL RADIATING I SYSTEM Filed Jari. so, 1945 2 Sheets-Sheet l ATTORNEY Sept. 3, 1946.

A.' ALFORD MULTISIGNAL RADIATING SYSTEM Filed Jan. '3o. 1945 2 Sheets-Sheet 2 lll- .www

. I N VEN TOR.

14A/DREW HLP-ORO ATToM Patented Sept. 3, 1946 STAT ES PATENT OFFICE MULTISIGNAL RADIATING SYSTEM Andrew Alford, New York, N. Y., assigner to Federal Telephone and Radio Corporation,

Newark, N. JL, a corporation of Delaware 13 Claims.

This application is a continuation in part of my copending application, Serial No. 445,944, filed June 5, 1942.

The present invention relates to systems for combining two or more signals and more particularly to such systems wherein at least one of said signals may be a course determining signal.

It is an object of my invention to provide a system for interconnecting two modulated radio frequencysources to a common line or load without substantial loss oi radio frequency power.

1t is a further object of my invention to provide an arrangement wherein two separate sources of modulated radio frequency may be interconnected to supply modulated energy to a common load in conjugate relation with a minimum oi energy dissipation.

It is a further object of my invention to provide a system for radiating directively signals defining a course line while at the same time radiating upon the same wavelength further signals such as signals representing speech and/or signals representing a further course line. More particularly it is an object to provide such a sys tem wherein both signals shall be radiated from one common antenna element while one of the signals, preferably the course line-defining signal, is additionally radiated from further antenna elements.

It is a further object to provide such a system wherein voice signals may be radiated from an element of a directive array used for beacon purposes while at the same time insuring that the voice signals shall not react upon the output stage delivering the beacon signals or vice versa.

t is a still further object of my invention to provide a system which shall simultaneously radiate directional signals for aiding navigation and other signals such as speech signals without any interaction between the sources of the two signals and without requiring that 50% of the power from each source shall be dissipated in so-called clumps or matching resistors.

When combining two signals (e. g., directive beacon signals and speech signals) for application to a single antenna element (or to a group of antenna elements connected together so as to act as a single antenna means) or other load, it is necessary that the connections be made so as to maintain approximate conjugacy between the two sources of signals (i. e., between the source of the beacon signals and the speech signal source). In other words, the connections should be made in such fashion that the varying voltage from the speech signal source shall have no effect at the output of the source of the beacon signals and vice versa. 'I'his requires that the two sources while being both coupled to the single antenna means must nevertheless not be coupled to one another. In order to attain such conjugacy various types of so-called conjugate networks may be used, such networks including the well-known Wheatstone bridge, the hybrid coil arrangement commonly used in carrier telephony and other types of arrangements specically de- Signed for coupling two sources to a load without intel-coupling the two `sources to each other. One of the most practical forms of conjugate network for use at high radio frequencies is the type disclosed in my United States Patent No. 2,147,809 issued February 21, 1939, for High frequency bridge circuit and high frequency repeaters, wherein there is described a sort of bridge made up of four lengths of 2wire transmission lines connected together in a square closed loop with a transposition in one of the four sections so as to prevent the effective transfer of power from any one corner of the square to the corner diagonally opposite while still permitting transfer of power from any corner to the adjacent corners.

A common characteristic of all known types of conjugate networks, whether of the preferred type just described or not, is that an impedance simulating the impedance of the useful load must be connected to the conjugate network and when so connected receives as much power as is transmitted to the useful load. Accordingly, when the conjugate network of the preferred type or any other type is employed for coupling to a common load the energy from a rst signal source and from a second signal source the required balancing resistor or dump which must be connected to the conjugate network will receive as much energy as the load thus requiring that the speech signal sources each generate twice the amount of power necessary for the load.

It is an object of the present invention to overcome the above disadvantage. It is a further object of the present invention to provide a system which may radiate from a common antenna both speech signals and other signals with reasonable emciency (i. e., without the dumping of large amounts of power) while at the same time maintaining the essential characteristics of the signals free from the inuence of any vacuum tubes, tuned circuits or other critical equipment used for supplying them.

More particularly, it is an object to provide such a system wherein the phase and amplitude 3 of the beacon signals will be comparatively unaiTected by the changing of tubes or retuning of the circuits used for speech radiation and wherein such eiects as shall be produced shall not tend to alter the directional pattern of the beacon signals.

In brief, the present invention attains the above and other objects by applying the one set of signals and other signals to a common antenna or other load via a conjugate circuit having a dump resistor and by arranging that both the signals applied to a common load comprise substantial carrier components of roughly the same orders of magnitude and of accurately related phases, these phases being so regulated that the amount of power dissipated in the dump is small compared to the amount of power usefully radiated from the common antenna.

The exact nature of the invention may best be understood from the annexed sheet of drawings in which:

Fig. 1 is a schematic diagram of a system embodying my invention and adapted to radiate directive beacon signals and speech signals;

Fig. 2 is a similar diagram of another embodiment of my invention wherein the two signals radiated are both directive beacon signals;

Fig. 3 is a schematic diagram of a portion of a circuit which maybe incorporated in the system of Fig. 2 in order to render the latter capable of simultaneously radiating two separate beacon signals and one speech signal; and

Fig. 4 illustrates two modulated sources con-V nected to a common load by a circuit incorporating my invention. e

Referring more specifically to Fig. 1, I, 2 and 3 are three antenna elements horizontally disposed in a straight line with the outer elements 2 and 3 equally spaced from the center element I. Preferably, each element is a loop of the type disclosed in Henneys Radio Engineering Handbook 1941, at page 601 and more fully described in my United States Patent No. 2,283,897, issued May 26, 1942,` for Antenna system, being thus adapted to radiate substantially pure horizontally polarized waves with substantially circular radiation patterns for each individual loop. In order to directionally radiate beacon signals modulated with 150 and 90 cycles, respectively, the circuit arrangement shown in the left hand portion of Fig. 1 is provided, this arrangement being essentially like that shown in my copending United States application, Serial No. 300,166, led October 19, 1939, now Patent No. 2,307,184, issued January 5, 1943.

Breily, this arrangement comprises the common source li whose output after passing the power amplifier 5 is applied to the lower corner of a bridge (i. This bridger is of the type described in the above-mentioned United States patent, No. 2,147,809, the transposition 6a being arranged in the upper right hand arm thereof and a balancing dissipating impedance I substantially simulating the loutput impedance of the amplifier 5 being connected to the upper cornerof the bridge so as to be essentially conjugate to the amplifier 5. A 2-Wire transmission line 8 is connected to the right corner of bridge 6 anda similar line 9 is connected to the left hand corner thereof so that energy is delivered to each of these lines from the ampliiier 5 although substantially no energy is delivered from this amplier to the balancing impedance 'I because of the effect of the transposition 6a.

Loosely coupled to the transmission lines 8 and almejas 0 are the short transmission line sections 8a and 9a whose effective electrical lengths are arranged to be varied cyclically at the rate of 90 cycles per' second and 150 cycles per second, respectively, thus cyclically tuning these line sections to resonance at the frequency of source li and then detuning them again. As a result of such cyclical tuning and detuning of the coupled sections 8a, and 0a the transmission of energy along the transmission lines 8 and 9 is cyclically varied so that the currents arriving in the upper portions of these lines 8 and 9 correspond to a` carrier frequency equal to the frequency of source 4 modulated with 90 cycles tone and 150 cycles tone, respectively.

These tone modulated signals are then applied from lines 8 and 9 to the right and left corners of a combining bridge lil whose lower corner is connected (through circuits more fully described hereafter) to the central antenna element I while the upper corner of this bridge I9 is connected to the outer antenna elements 2 and 3. As shown, the connection from the upper corner of bridge I0 to antenna element 3 includes the transposition II while the corresponding connection to antenna element 2 includes no such transposition thus insuring that the antenna elements 2 and 3 are excited in phase opposition to one another.

It should be noted that because of the transposition Ilia of bridge I0 the energy delivered to the outer antennae 2 and 3 contains no unmodulated carrier component since this component is balanced out. Thus, the antenna 2, for example, contains only the side bands corresponding to the 90 and 150 cycle signals (e. g., c-I-90, c-90, c-I-150 and c-150 where c is the carrier frequency). The antenna 3 contains the saine four components in opposite phase. The power delivered from the lower corner of bridge I0, on the other hand, contains a very strong component of carrier frequency c as well as of the four side bands above described.

Temporarily assuming that the lower corner of p bridge I0 is directly connected to antenna I Without any intervening bridge structure and assuming that the electrical length of the path from such lower corner of bridge I0 to antenna I is 90 longer than that of the path from the upper corner of bridge I0 to antenna 2, it will then be clear that the 90 cycle side band components radiated from antenna I will add to the radiation of the corresponding side bands from antennae 2 and 3 in that region toV the north side of the course line WE while tending to oppose such radiation on the south side of such line. The reason for this is that the 90 cycle side bands must pass through one transposition in traveling from transmission line 8 to antenna 2 while encountering noY transpositions but only a 90 greater length of line when traveling from transmission line 8 to antenna I. Accordingly, the radiation of the 90 cycle side bands from antenna 2 will be 90 retarded with respect to the corresponding radiations from antenna I. At the same time the corresponding radiations from antenna 3 will be 90? advanced compared to those from antenna I because of transposition II. While the radi- 1 ations from antennae 2 and 3 exactly cancel along `the course line WE, the vectorial combination of North of the course line WE, the radiations from antenna. 2 will arrive in a shorter time than those from antenna 3 thus effectively advancing the phase of the radiations from 2 and retarding the phase of those from 3 with respect to the phase of radiations from antenna I. Therefore, the resulting radiation from antennae 2 and 3 combined will be in phase with the corresponding radiation from antenna I at anyv point north of the course line. Conversely, the 150 cycle radiation from the antenna 2 will be 90 advanced in phase with respect to the corresponding radiation from antennaV The resultant 150 cycle side band radiation from antennae 2 and 3 will' tend to add to the corresponding radiation from antenna in the region south of the course line WE while subtracting therefrom in the region north of this course line.

The aparatus so far described corresponds to that disclosed in detail in the above-identified application, Serial No. 300,166, a detailed understanding of the operation of such arrangement being desirable for full appreciation of the present invention.

The further apparatus 20--25 is associated with the apparatus already described for the purpose of applying speech signals to antenna I simultaneously With the beacon signals heretofore described. Such additional apparatus essentially comprises a speech source 20 (illustrated as a telephone transmitter but preferably comprising a microphone and suitable audio amplifier stages) connected to modulate an R-F amplier 2| which is excited in parallel with the amplier 5 from the carrier source 4. The speech modulated output of. amplifier 2| which is preferably of the same order of magnitude as the output of ampliiier 5 is transmitted through phase shifter 22 to the right-hand corner of conjugate bridge network 23, which is preferably of the type described in the above-mentioned United States Patent No. 2,147,809.

As shown in the drawings, the upper corner of the bridge 23 is connected to antenna and the left hand corner thereof receives the proper beacon signals from the lower apex of combining bridge it' earlier described. Thus, both the speech modulated signals from amplifier 2| and the combined carrier and four side bands of the beacon signals from combining bridge I are transmitted via bridge 23 to antenna I. In order to insure conjugacy between the speech signals from amplier 2! and the beacon signals from the lower corner of bridge I0, bridge 23 is balanced by means of transposition 23a and a balancing dissipating impedance 24 whose impedance as viewed from bridge 23 is equal to that of the antenna element I as viewed from this same bridge, A radio frequency voltmeter 25 is connected across the line between the lower corner of bridge 23 and the impedance 24 for a purpose hereafter to be described.

it should be noted that the signals from modulated ampliner 2| and the beacon signals from the lower corner of combining bridge I0 are not only of the same wavelength but both contain a substantial component of carrier frequency derived from the common source 4. 1n the case of the beacon signals this carrier frequency component has a phase dependent upon the characteristics of power amplier and this phase may vary due to adjusting of the tuned circuits of this amplifier or even, to some extent, due to the two variations in the tube characteristics thereof. In the case of speech signals from amplier 2| also the phase` of the carrier accom- 6r, panying these speech signals` is dependent upon the characteristics of amplier 2| and thus can be varied due to adjusting the tuned circuits of this amplier or even by virtue of changes in the tube characteristics thereof.v The phase shifter 22 is. provided to take care of these variations in phase andV is intended to be setv so that the phases of the carrier components in the speech signals and in the beacon signals are alike at the points where these signals are applied to the right and left corners of bridge 23, respectively. If this phase relationship is attained and if the magnitudes of the carrier components of the two signals are alike, it will then follow that no carrier frequency energy will be dissipated in impedance 24 because of the effect of transposition 23a. Even if the carrier power from speech amplier 2| be assumed to be only half as great in amplitude as the carrier power from the bottom of bridge I0 (so that the corresponding voltages are in the ratio of .707i to 1) it can readily be seen that the voltage at the 'upper corner of bridge 23 will correspond to l-I-.707 (i. e., to 1.707) while at the lower corner it will correspond to 1'-.707 (i. e., to .293). rIhe corresponding powers will .be proportional to (1.70.7)2V and (.293)2 respectively, being thus in the ratio of 2.9' to: .086, i. e about 34 to 1. Thus, when the carrier component from amplifier 2| is only half asV great as the corresponding power from. bridge I0 it still appears that the power dissipated in dump 241 is less than 3% of the carrier power usefully radiated from antenna I.

With respect to the side bands of the speech signals and the beacon signals it is true that substantially 50% dissipation occurs in impedance 24 but in most cases the average side band power is considerably smaller than the average carrier power and therefore the total amount of wastage is a comparatively small percentage of the total energy usefully radiated from antenna I.

One great advantage of the arrangement in Fig. 1 is that phase variations introduced in the amplifiers 5 and 2| (by virtue of the adjusting of the associated tuned circuits or variations in the tube characteristics thereof) do not alter either ythe position of the course line defined by the beacon signal or the shape of the radiation pattern in respect to relative strengths of the and 90 cycle signals at. anyY points in space. It is also true that if .the phases of the carrier components delivered by the ampliers 5 and 2| vary in opposite sense by a considerable number of degrees a substantial dissipation of power in impedance 24 will result since the carrier components arriving at the right and left corners of bridge 23 will no longer be in phase. Such a result, however, is by no means as serious as a distortion of a beacon radiation pattern. Furthermore, the dissipation of energy in the dump 24 is constantly indicated bythe meter 25 and therefore any person adjusting the tuned circuits associated with either amplifier 5 or 2|A will be immediately apprised of any incorrect phase relationship.

It should be observed that even if a very large difference in phase exists between the carrier components from` amplifiers 2| and 5 the side band components of the beacon signal radiated from antenna willstill be properly phased with respect to the corresponding side band components of the beacon signal radiated from antennae 2v and 3. Also, these side bandA components will be properly phased with respect. to the portionA ofv the carrier'. component which. is derived from amplifier 5. If, therefore, the two carrier components supplied by amplifiers and 2| are of equal magnitude, then a phase shift as much as 60 between the phases of the carrier components supplied from the two Iampliers will result in a phase shift of only between the resulting combined carrier radiated from antenna I and the beacon side bands. Such a phase shift will not alter the beacon pattern at all (in viewL of the fact ythat the side band components in the several antennae are properly phased) but instead will only decrease the efficiency of demodulation at the receiver by decreasing the amount of useful carrier component available for demodulating the signals. This effect is not :at all serious unless the phase relationship between the carriers becomes as great as 180, in which case the resultant carrier being 90 to the side bands would not be useful for producing demodulation in the receivers. It is clear, however, that the phase shifts of the amplifiers are not likely to equal 180 especially with the constant check provided by meter 25.

With respect to the speech frequencies the shifting of the carrier with reference to the side bands is also somewhat undesirable since it tends to'produce harmonic distortion. Such distortion is unimportant if the percentage modulation is small. In the system shown, moreover, half the carrier component isderived from amplifier 2| and therefore does not shift.

Thus a phase shift of 60 between the two carrier components would only shift the combined carrier by 30 with respect to the speech side bands. YThese two factors (i. e., the effect of low modulation percentages in preventing distortion and the fact that only half the phase shift between carriers appears as a phase shift between the combined carrier and the side bands) both tend to reduce the amount of distortion encountered in practice. Thus, as a practical matter, under ordinary conditions with a modulation percentage around 80% a phase shift as large as between the two carriers will not produce an intolerable percentage of harmonic distortion in the speech signal.

Although the invention has so far been described as used for radiating speech signals and beacon signals from one common antenna element (e. g., antenna element I of the array I, 2, 3), the invention is also capable of other uses. Thus, for example, it may be used for radiating two separate beacon signals from a common antenna, such an arrangement being illustrated in Fig. 2.

Referring more particularly to Fig..2 the components I, 2', 3', II', 5', 8'., 6a', l', 8', 8a', 9', 9a', I0', Illa' and II' correspond exactly to the elements of Fig. 1 having corresponding unprimed designations. These elements together constitute a beacon defining a west-east course line exactly as described in connection with Fig. 1.

The bridge 23 with its transposition 23a and its dump 2li' and its meter 25' serve, as in thev the same carrier frequency. In the case of Fig. 2A

such additional independent Set of signals is assumed to be another set of beacon signals rather y than a speech channel as in Fig. 1.

The equipment for providing the additional.

beacon signals comprises the power amplifier |05; the two transmission lines |68 and |09 with their modulating equipments |0811 and I09a; the bridge |05 for transmitting the power to these lines |08, |09 from the amplier |05; such bridge being provided with a transposition lEa and a balancing impedance |01 in order to prevent the modulator of |00a of channel |09 from reacting on the channel |08 or vice versa; the combining bridge I I0 with its transposition I Illa and the antennae |02 and |03. All of this equipment operates essentially like the correspondingly numbered equipment in Fig. l (the number |08 being considered as corresponding to the number 8, etc.). The side antennae |02 and |03 are fed antiphasally with the four side bands corresponding to a 1020-cycle modulation and a 1300-cycle modulation, these side bands having the frequencies c-l-lOZO, c-1020, c-l-1300, and c-1300. The

central antenna I is fed from the lower corner of bridge I IIla with .appropriate signals having a strong carrier component and also including the same four side bands which are radiated from antennae |02 and |03. .The bridge 23 combines the signals from the lower corner of bridge ||0 with those from the lower corner of bridge I0'. Each of these signals to be combined contains a substantial carrier component and these components are ofthe same order of magnitude (i. e. the ratioof the powers is less than 10:1). The phases of the carrier components arriving at the left hand and right hand corners of bridge 23 should be alike and this condition may be attained by adjusting the tuned output circuits of amplifiers 5 and |05 to produce the desired phase relation. In case a more convenient adjustment is desired, a phase shifter may be provided just ahead of amplifier 5' or |55 or immediately following either or both of these ampliers. The meter 25 will serve to show when the desired phase condition is reached, since this meter will read Zero or a minimum when the carrier components arriving at the left and right corners of bridge 23' are in phase. In the system of Fig. 2, an east-west course line is defined by the equality of the 150 cycle modulated signals and the cycle modulated signals, while a north-south course line is defined by the equality of the 1020 cycle modulated signals and the 1300 cycle modulated signals. For properly generating the beacon patterns to define these course lines, antennae 2' and 3' and |02 and |03 should be fed in phase quadrature with respect to the central antenna I. Accordingly, the electrical length of the path from the upper corner of bridge I0 to antenna 2' may be 90 shorter than the length of the path from the lower corner of bridge IIJ' to antenna I'. Similarly, the length of the electrical path from the upper corner of bridge III) to antenna |03 may be 90 shorter than the length of the path from the lower corner of bridge I I0 to antenna I'. These relationships may be satisfied by suitably choosing the lengths of the transmission lines. If desired, however, phase-shifter equipment can be inserted between Vthe upperl corner of bridge I0' and the antenna array and other phase-shifting equipment may be inserted between the upper corner of bridge I0 and the antenna array. Such phasing equipment, if provided, would be adjusted for initially aligning up the courses and would thereafter not be disturbed.

lfit is desired to combine more than two signals upon a common antenna, this may be done by extending the principle of the present invention.

Fig. 3 illustrates how Fig. 2 could be modified to vfier 22! which is modulated by speech source 220 feeds its speech modulated output to bridge 223 in essentially the same way that amplifier 2l fed its output to bridge 23 in Fig. l. In the system of Fig. 2 as modified by Fig. 3, the additional input which is combined with the speech signals in bridge 223, arrives from the lower corner of bridge I I and in order to minimize losses in the dump 224, the phases of the arriving carrier components may be adiusted by adjusting the tuned output tank of amplifier HB of modulated ampli- -iier 221, or both. If desired, however, a phase shifter'may be included before or after either or both of these amplifiers. The output from bridge 223 'is applied to the right hand corner of bridge 23 where it is combined with output from the lower corner of bridge l0. Preferably, the amplitudes of the carrier components arriving at the upper and lower corners of bridge 223 (from amplifier 22K! and the lower corner of bridge I I0) should be approximately equal in magnitude and should each be approximately half the amplitude of the carrier components delivered from the lower corner of bridge lil. Thus, the combined carrier delivered from the left corner of bridge 223 will be of substantially the same amplitude as the carrier delivered from the lower corner of bridge l0 and therefore substantially no dissipation of vcarrier energy will occur in the dump 24.

In the circuits of Figs. 1, 2 and 3 a circuit according to my invention has been shown for combining beacon signals and speech signals. The circuit is useful, however, for combining modulated radio frequency energy from any two sources.

In Fig. 4 is shown a rst source of carrier modulated signal '60H and a second source of modulated signal 402. These sources are of the same radio frequency but carry thereon different signal energies. The modulations may be of any desired type, for example, they may be intermediate carriers modulated with signals to be applied to a multiplex line 423. Sources Ml, 402 are applied to the opposed d'iagonals of bridge 404, having a transposition 405. A balancing dissipating network 406 is coupled to the bridge terminal opposed to load line 403 and is proportioned to match the impedance of the load. Thus, two sources are interconnected so as to have no reaction one on the other, and yet relatively wide variations in amplitude and phasing of the signals may be permitted without destroying the substantial advantages of the system.

If desired, 450|, 402 or both, may include `arnplitude and phase adjusting means so that adjustment may be made until minimum lcurrent is applied to dissipating network 4835 as indicated in meter li111.

Although it is preferred that the two carrier components to be combined in any one of the bridges (e. g. 23. 23', 223 or 404) are preferably oophasial and oi equal magnitudes, very wide departures from this condition may be tolerated while still giving surprisingly'small losses in the dum-p balancing resistor. Thus, for example, a 4:1 power ratio will result in a dissipation of only of the total power; 90% of this `power being transmitted to the useful load. Even a 10:1 power ratio results in wasting only about 21% of the total power (which is a very substantial improvement over the 50% power Wastage incurred with the ordinary conjugate circuit arrangements, without controlling the phases of the carriers). In respect to phasing, also a considerable latitude is permissible. Thus if the 5 two carrier components to be combined are equal in power, a phase divergence Of as much as causes the dissipation of only .about 61/2% of the total power while even a phase divergence as large as 60 causes the dissipation of only about 25% of the total power.

Although the invention has been particularly described for combining two signals one of which is a beacon signal, it can also be used for combining two signals of any type, for example, phase and amplitude modulated signals vemploying the same carrier or telegraph and telephone signalsY based' on the same carrier.

For` convenience, the illustrated embodiments of the invention show the modulation as effected at audio-frequencies (i. c. by audible frequency tone modulators producing power tones of 90 cycles, 150 cycles, 1020 cycles or 1300 cycles, or by speech frequency modulating equipment. It should be understood, however, that the modulation may be performed at `super-'audible or subaudible frequencies and may lconsist of or include the process of 'keying in A-N rhythm or other rhythm. Thus, the expression modulation as used in the appended claims should `be interpreted in its broader sense to include `all modifications of the amplitude, phase, or frequency of the carrier by any of the commonly used processes ordinarily referred to as modulation or keying.

Although certain embodiments of the invention have been shown and described for purposes of illustration, it will be understood that variations, adaptations and modifications thereof occurring to one skilled in the art may be made without departing from the scope of `the invention as defined bythe appended claims.

What is claimed is:

1. A `system for simultaneously applying two Vsignals on the same carrier lfrequency wavelength to a common useful load which comprises a 'first signaling means for producing 'a iirst side band component and a first carrier component, second signaling means for producing a second side band component and a second carrier component, common load means, a balancing dissipating element simulating the impedance of said common load means, a balanced network connected to transfer energy from said first and secon-d signaling means to said common load means and .55 with a relative phase reversal to said balancing element while maintaining substantial conjugacy between said first and second signaling means, and carrier synchronizing means for maintaining said first and second carrier -components at the same frequency and in a predetermined phase relation such as to minimize the absorption of carrier energy in said balancing element.

2. A system for simultaneously applying two signals on the same given carrier frequency wavelength to a common useful load which comprises a iirst signaling means for producing a first side band component and `a first carrier component of said given wavelength, second signaling means for producing a second side band component and a second carrier component of said given wavelength, common useful loa-d means, a balancing element simulating the impedance of said load means, a, balanced network connected to transfer energy from said iirst and second signaling means to said common useful load and with a relative phase reversal to said balancing element while maintaining substantial conjugacy between said iirst Iand second signaling means, and means for adjusting the phases of said first and second carrier components thereof as measured at the input to said balancing'element substantially into opposition. p

3. A system for simultaneously applying to a common useful load two signals on the same carrier frequency wavelength which comprises rst signaling means for producing a rst side band component and a first carrier component, a second signaling means for producing a second side band component and a second carrier component, said carrier components being of the same radio frequency, a dissipating balancingelernent simulating the impedance of said common load, a balanced network connected to transfer energy from said rst and second signaling means to said common load and with a relative phase reversal to said balancing element while maintaining substantial conjugacy between said rst and second signaling means, carrier synchronizing means controlling said rst and further signaling means to maintain the phases of said carrier components substantially opposite as measured at the terminals of said balancing element. Y

4. A system according to claim 3 wherein said rst and second signaling means are adjusted to transmit to said balanced network carrier components of substantially the same Iorder of power.

5. A system according toY claim 3 wherein said first and second signaling means are adjusted to transmit to said balanced network carrier components, the ratio of whose powers is less than 3 to 1. l

6. A system for simultaneously applying to a common load two signals on the same carrier frequency wavelength which comprises rst signaling means for producing a rst side band component and a first carrier component, second signaling means for producing a second side band component and a second carrier component, a dissipating balancing element simulating the impedance of said common load, a balanced network connected to transfer energy from said first and second signaling means to said common load and with a relative phase reversal to said balancing element while maintaining substantial' conjugacy between said first and second signaling means, carrier synchronizing means controlling said first and second signaling means to maintain the frequency of the carrier components identical and the phases of said carrier components within 60 of being opposite.

'7. A system for simultaneously applying two signals on the same common carrier frequency to a common load comprising a rst source of modulated energy having a carrier componentof said common frequency and side band components, a second source of modulated energy having a s'econd carrier component of said common frequency and other side band energy, a dissipating ele- Y ment simulating the impedance of said common load, a balanced bridge having four diagonally arranged points, means for applying energy from said rst modulated energy source and said second modulated energy source to opposite diagonal points of said'bridge, means for coupling said load to another of said diagonal points to receive carrier frequency energy and side band frequency energy from both said sources, means for coupling said dissipating network to the other'Y said point on said bridge diagonally opposite to. said load connection, means in said bridge for Yproducing a phase reversal of energy from one of said sources intermediate the connection points of said source and said dissipating network to the said y5 bridge and means for maintaining energy supplied from said sources to said bridge substantially in phase coincidence whereby carrier frequency energy is substantially balanced out at the input of said dissipating'network and substantially only side band energy is dissipated in said network.

8. A system in accordance with claim 7 wherein each of said sources comprise independent amplifier arrangements and said means for maintaining energyY applied from said sources to said bridge substantially in the same phase comprising a phase shifting network for adjusting in phase energy from one of said modulated sources with respect to energy from the other of said sources.

9. A system for simultaneously applying carrier energy of the same frequency but modulated with different characteristic signals to a common radiating means, said signals each comprising a carrier frequency component and respective side band components comprisingV a balanced four arm bridge circuit, means for coupling saidV radiating means to a rst point on said bridge, a dissipating network means for coupling said Ydissipating network to a second point diagonally opposite said first point, means Yfor applying carrier and said band components from each of said sources to respectively opposite terminal points of said bridge to supply carrier frequency energy and side band frequency energy from both sources to said common radiating means, and means for maintaining energy from both said sources 'over said network to said dissipating network in such phase relationship that said carrier components from the respective sources are substantially in phase opposition whereby substantially no carrier frequency energy Vis dissipated in said network, said side band components both being applied to said network for dissipation.

10. The method for simultaneously applying two signals on the samewavelength to a common useful load over abalancing network designed to maintain conjugate relation between said signals which comprises producing a first carrier component at said wavelength and an associated rst side band component, producing a second carrier component at said wavelength and a second associated carriercomponent, applying said rst carrier component, said first side band component, said second carrier component and said second carrier side band component to said load over said network in such phase relation that said carriers are substantially in phase coincidence in said load and applying said components over said network to said dissipating network in such phase relation that the rst and second carrier components are substantially in phase opposition at the inputin said dissipating network whereby substantially only side band energy is dissipate in said dissipating'network. Y

1l. The method in accordance with claim 10 the further step comprising adjusting the relative phase in said first and second carrier components to maintain the desired phase relationship therebetween atV said load and said balancing network.`

l2. A system for simultaneously radiating course indicating signals and voice signals simultaneously from the same antenna system on the same carrier frequency comprising a rstcarrier frequency source, means for modulating en- 14 and means in said balancing networks for maintaining carrier frequency energy from both of said sources substantially in phase coincidence at said common antenna and substantially in phase opposition at said dissipating network.

13. An arrangement in accordance with claim 12 further comprising means for shifting the phase of said voice modulated carrier energy before application to said balancing network to assure proper phase relation of said carrier energy at said antenna and at said disspating network.

AN DREN' ALFORD.

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