US1668637A - Directive radio repeating system - Google Patents

Description

L. EsPENscHn-:D E1' AL DIRECTIVE RADIO REPEATING SYSTEM MuyA s, 192s. 1,668,631

Filed Dc. 28, 1921 4 Sheets-Sheet 1 May 8, 1928. 1,668,637

K L. ESPENSCHIED ET AL DIRECTIVE RADIO REPEATING SYSTEM Filed Deo, 28, 1921 4 Sheets-Sheet 2 7 X2 /s j; f ii 72 l; f5, Y lm-wlw@ @Q j l 56p k llllli -Il iIll l j ATTORNEY my s, xsi-2a l.. 4EsF'rsNscHlr-:D ET Al.

-DIRECTIVE RADIO REPEATING SYSTEM Filed DfQzs, 1921 4 Sheets-Sheet 3 INVENTQRS ATTORNEY May 8, 1928.

L. ESPENSCHIED ET AL DIRECTIVE RADIO REPEATING SYSTEM Filed Dec. 28, 1921 4 Sheets-Sheet 4 ATTORNEY Patented May 8,1928.

UNITEDSTATES 1,668,637 Pari-:rrrA ori-icaN LLOYD ESPENSCHIED, or QUEENs-NEWYORK, AND nnnoss K. MARTIN, oF ORANGE, NEW JERSEY, AssIGNoRs To `AixerriucAN TELEPHONE AND TELEGRAPH COMPANY,

A CORPORATION OF VNEIN'` YORK.

DIRECTIVE RADIO REPEATINGSYSTEM.

App1icaton-1led Decemberi28, 1921. `Serial No. 525,440.

This Vinventionrelates to directive radio repeating systems `and particularlyr `to that type ofsystem adjusted to have abilateral receiving and transmitting characteristic 5 and in which transmission and reception oc` cur at the same frequency.`

The radio repeating systems heretofore designed comprise a single antenna and an amplifying circuit connected therewith which were` adapted to amplify Vwaves received from any direction and transmit the amplified waves in all directions. `N ot only were these systemsineilicient because of the lack of a directional characteristic in receiving` and sending but also the degree of amplification was somewhaty low, being limited by the tendencyV of the repeater to sing.

One of the objects of this invention'is to provide a repeater system having controllable directivity, and balanced so that great amplification can be obtained without producing singing in the repeater circuit and thereby rendering it inefficient. i Another object of this invention to pro` ride a system suitable for long distance signaling in which the effects of static are minimized by the use of short waves, which, as is well known, are less affected by static than are long waves. Furthermore, the effect of static maybe minimized by sustaining throughout the course of transmission the ratio of the signaling energy to static, which result may be attained by spacing the directive repeating stations at certain predetermined points, depending upon the drop in the energy level between the successive repeating stations. i

By the use of repeating stations embody-` ing directive antenna arrays such, for eX- ample, as aredescribed in the copending application of G. A. CampbelLSerial No. 327,- 553. filed September 30, 1919, and properly designed and adjusted amplifying circuits, the course of transmission 1of signals between widely separated terminals may be controlled, since it is practicable, by` properly locating the repeating stations, to direct the transmission either along a straight line between the two terminals, or along a more devious course. This `feature of our invention becomes important when it is de- ,sired to avoid objects lying between the two terminals which would tend to interfere with former being characterized by a verticalA antenna array and the latter by a loop an` tenna. array; Fig.V 3 shows a alanced arrangementl using horizontal and Vertical antennae: Fig. 4 shows an arrangement using horizontal and vertical antennae adapted for duplex operation; Fig. 4 shows the radiation characteristic of the arrangements shown in the foregoing figures and Fig. 4b is a. frequency chart of Fig. 4; Fig. 5 shows an arrangement for receiving by a loop antenna andtransmitting by a vert-ical antenna, the characteristic of the loop antenna being shown in Fig. 5a; Figs. 6 and 6a show other forms of circuits similar to Fig. 5, but adapted for the duplex operation; Fig. 7 shows a circuit having separate receiving and transmitting antenn and characterized b v a connecting circuit between the transmitting and receiving antennae to prevent interference between them; Figs. 8 and 9 show completeradio` systems embodying a directive repeater for relaying the signals betweenthe terminal stations, Fig.` 9 being distinguished from Fig. 8 by the use of a single source of carrier oscillations for modn` lation and demodulation at both terminals; and Fig. l() shows a method for arranging repeater stations to prevent singing between adjacent ones.

In Fig. l, X1, X2 and X, represent three antennae of an array, which are spaced a definite part of a wave length apart. Each antenna has connected theretoan amplifymg circuit having a phase shifting device the input side of the amplifying circuit, and a power amplifier A2, a band filter F1 and a phase shifting device PS2 inthe output side of the said circuit. The antenna X, is connected with the amplifying circuit byymeans of the multi-winding transformer T, with which is also connected a network N, designed to balance the antenna X1. The an* `FS1 a band filter F1 and an amplifier A, in

tennae X2 and X3 are connected with amplifying circuits similar to that shown in connection with the antenna Xl. Y

Oscillations set up in the antennae as the result of anelectromagnetic wave will beimpressed'by the transformers upon the input side of the amplifying circuits. Thus, for example, oscillations set up in antenna Xl will be impressed by the transformer T1 upon the amplifying circuit. The phase of the current will be changed by the phase shift-ing device PS., and the current will then pass through the band filter F1, which is preferably designed to transmit a band of frequencies represented by the carrier frequency plus the signaling frequency er the carrier frequency minus the signaling frequency. The currentl traversing the band ilter will be amplified, liistby the low power amplifier A, .and then by the high power amplifier A2. The resultant current will be transmitted through the band filter F2 having the same characteristic as the filter Fl. The phase shifting device PS.I is designed to control the phase of the current applied tothe antenna Xl for transmission therefrom. By properly spacing the antenna constituting the array and by the proper control of the amplitude and the phase of the currents applied lto the individual antenna of the array according to the principles set vforth in thecopending application to G. A. Campbell, Serial No. 827,553, filed September 30,1919, ive may obtain, for example, the bilateral radiation lcharacteristic shown in Fig. eta. This characteristic indicates maximum receiving and transmiting efficiency along the axis of the characteristic, which is perpendicular to the axis of the array. It will accordingly be seen that by means of the repeater arrangement shown in Fig. l, adjusted so as to have the characteristic shown in Fig. Il", it is practicable to receive signals from both directions perpendicular to the axis of the array and to transmit amplified signals in both directions from the axis of the array. The frequencies of the received signals depend, of course, upon the timing of the autenn and also upon the frequency range of the band filters. Since reception and trancmission are effected on the same frequency, it is necessary to balance theindividua'l vantennae by means of a balancingnetivork such as N1 shoivn in connection with the Xl in order to prevent the continuous circulation of energy Within the repeater circuit, known as singing.

The arrangement shown in Fig. .2 is in generalsimilar to thatshown in Fig. 1, excepting that loop antennae take the place of the vertical antennae shown in Fig. 1. The characteristic of loop antenna, shown in Fig. 5, indicates maximum reception and transmission of energyT along an axis lying within the plane of each antenna constituting the array. The loops aie adjusted for the reception and transmission of signalsof the same fre uency. The current setup in the loop by tie high frequency Wave Will beimpressed upon the input branch of the amplifying circuit passing through the phase shifter PS1, the band filter F1, and low power amplifier A, then through the high power amplifier A2, a second band filterFg and a second phase shifter PS2, which controls the phase of the current applied through the transformer Tj to the loop antenna. By proper spacing of the loops and by proper control of the amplitude and phase of the current applied to each antenna, of the array, the direction of reception and transmission of signals may be controlled. The advantage of using the loop array is that the same degree of directive transmission or reception may be obtained with fewer units than with the vertical array. Since transmission and lrecept-ion are effected by the same carrier frequency, singing is prevented by the proper balancing of the loops by the networks Nas shown in the ligure.

1ig. 3 shoivs a repeater, adjusted for re ceiving and transmitting upon the same fre quency, in which signalsy are received by a horizontal antenna which is balanced with respect to the vertical antenna which transmits the amplified signals. 4Tn tliisarrangement each unit lcomprises ahoriaontai antenna, a vertical antenna and an amplifying circuit. Although in the figure the vertical and horizontal antennae of each unit are shown in close proximity to each ,ilher,

and the arious units are spaced at delinif.: fractions of a Wave length. apart, itis desiicd to point out that all of the vertical :iiiteiinee maybe arrangeril in a group, ear-h located at the proper distance from the others, and similarly all of the liorh/.ontal antenna may be grouped together. euch located at the proper distance from the others. This noce fates, however, that the rei-pective amplifying circuits must extend from a horizontal antenna to its ,orr .e,-spondin;r transmitting antenna located in vtlieolher group, `which may be some distance array. Theamplifying circuit itself comprises plia shifting devices, bund filters and amplifie similar to those described in connection with the previous figures. In a radio relay el' this type, received signals set up currents in the horizontal antenna which are transmitted through the phase shifting device PSL, the filter F1 and the levi power ainpliiier A1, thence through the power amplifier A2, the filter F2 and the phase shifting device PS2, tothe transmitting 'antenna X1. Although reception and transmission are effected upon the saine frequency singing is preventedthrough the balanced relationship of the same frequencies as X2.

horizontal antenna tothe vertical antenna.Y

By proper spacing of the antennae and byV proper control of the amplitude and phase of the currents applied to the individual antenna of the array, radio signals may be re` layed and the direction of transmission may be controlled.

The arrangement shown in Fig.` et, While operating upon the principle of transmis-` sion and reception of signals upon the same frequency, is designed for the simultaneous transmission of tvvo channels either in the same or in opposite direct-ions.V The `antenna structure is of *the balanced type shown in Fig. 8, With the exception that both the ground antenna and the vertical antenna have two degreees of freedom. the operation of the arrangement shown in this figure, if a wave representing a band of frequencies such as fl-l s or )c1-18 strikes the horizontal antenna, oscillations Within the band of frequencies will lbe set up in the horizontal antenna. The Vcurrent `Within this band of frequencies will be transmitted through the phase shifting device PS1 and through the band filter F,l `to the amplifier A1, thence throughthe power amplifier A2 and the second band `filter F2, which is adapted to pass the same range of frequencies as F2, and then throughthe phase shifting device PS2 to the vertical antenna X, Which as stated, is adapted to oscillate at the Since the antenna X1 occupies such a position With respect to the horizontal antenna X2 as not to create oscillations in X2 when Xlis radiating, relatively high amplication can be obtained without producing singing of the repeater. In a similar manner if a Wave representing a band of frequencies )i2-ts or f2-s strikes the ground antenna X2, oscillations of the same band of frequencies will be set up in the said antenna. These oscillations will be transmitted through the phase shift-ing device PS3 and the band vfilter F which is designed to transmit Athe range of frequencies represented by f2-te or f2'm a; Thecur- .rent Within this band of frequencies `will` be amplified by the loW power amplifier A.L and also by the high power amplifier A2, and vthe resultant amplified current Will be trans mitted through the band filter F4 and then through the phase shifting device PSd to the antenna X1 which will oscillate at the transmitted frequencies. Although the amplitiers A, and A2 are represented as being common to the paths of the tivo channels, it is, of course, apparent that separate amplifiers of both types individual to the paths of the tivo channels could be used.

The arrangement'shown in Fig. 4 constitutes only a single unit of a radio repeating system, but it is to be understood that there will be a plurality of such units constituting a repeating station in which the adthe manner. described in connection with Fig. 3, and the transmitting antennae Will be similarly spaced. By properly controlling the phase and the amplitude of the received and transmitted current on each'unit circuit of an array, the direction of transmission and reception may be readilycontrolled.

Fig. 5 shows a unit circuit of a repeating station characterized by separate receiving and transmitting antennae, the receiving antenna being of the loop type and the transmitting antenna being vertical. Oscillations of the frequency f, +S or f2-s received by the loop antenna X2 will be transmitted through the amplifier A1 and the phase shifting device PSL and the band filter F, to the power amplifier A2 connected with the trans mitting antenna X,. Since the radiation and reception characteristic of a loop antenna is, as shown in F ig.V 5, such that the maximum eiiiciency is along a line coinciding with the plane of the loop and the minimum c'liciency along the axis perpendicular to the loop, interference from the oscillations transmitted by antennae as X1 can be substantially` prevented by adjusting thephase shifting device PS1 so that the transmitting antenna Will have a characteristic for example, slich `as is shovvn in Fig. 4 `with the major axis of the characteristic perpendicular tothe plane of the receiving loop. Accordingly interference may be substantially prevented even though the two antennae are responsive to the same frequencies. The arrangement shown in Fig. 5 constitutes but a single unit of the radiating system and it to be understood that there will be a plurat ity of antennsearranged inan karray with suitable local. circuits individual to each pail' of receiving and transmitting antenua..

` Figs. 6 and 61" are modifications of the form shown "in Fig. 5, the modification consisting in arranging a structure for the s multaneous reception and tansmissimi of two channels. Thus the `loop X2 is respon sive to carrier frequency f', and the loop X/ is responsive to the carrier frequency f2. In Fig. 6a a single loop.k having two degrees of freedom such as the frequencies f, and f2 takes the place of the twoloops iu Fig.` 6. The t 'ansmission of currents at these frequencies through the local circuits to the transmitting antenna X, is similar to that described in comiection with Fig. The circuit arrangements shown in Figs. f3 and 6a are units of a radio repeater sr tem ,and there Would be, of course, a plurality roo the directional characteristic shown in Fig. t,

Fig. 7 is a variation of the idea embodied in Fig. 5. The repeater circuit illustrated by F ig. 7, which represents one unit of a directive repeating station, is intended for: the transmission of amplified signals having the same frequency as the received signals. The circu-it contains a receivingr loop X2 for receiving oscillations of th frequency 7' which are amplified. by the low power amplifiers A, and A. and impressed upon the band filter F,. Current of the frequencies transmitted through the band lter F1 will be amplified by the power an'iplilier A: and impressed upon the transmitting antenna X1. Freedom from interference from the transmitted oscilla tions obtained partly by proper orientation of the loop antenna and partly by feedingl from the transmitting antenna to the circuit of the loop antenna a certain ani-.cunt of current, the phase of which as applied to the loop circuit `is controlled by the phase shifting device PS1. The phase angle of this transmitted current. which may be termed the neutralizing current, when applied to the loop circuit is suchv as to neutralize currents set up in the said loop as the result of direct radiation from the ltransmitting antenna thereto. The arrangement shown in Fig. 7 represents but a single unit of an array, and there would, of course, be a plurality of antennae suitably spaced and having a local connecting circuit individual to each pair of receiving and transmitting antennze.

Fig. 8 represents a complete ,system comprising two terminal stations A and B, and a repeater station vC intermediate the said terminal stations. The repeater station comprises an array of transmitting antennte X X2 and XM and also an array of receiving antennae represented' as loops and X1 X2 and X3. Each pair of transmitting and receiving antennze is connected by a local circuit, such for example, as that shown connecting the antennae X2 and X2 containing a low power amplifier AU a phase shift ing device PS a band filter F, and a powcr amplifier AT At each of the terminal stations a low frequency signaling circuit L, is connected with the terminal circuit by means of a triple winding transformer T, which hasl associated therewith a network N, designed to balance the line LV The input side of the terminal circuit comprises a receiving loop X] an amplifier A3, a detector Dl and a second amplifier Ay The output branch of the said terminal circuit comprises an amplifier A5, a modulator Ml and an oscillator O, which is connected with the transmitting antennae X1. The apparatus constituting the terminal station B is similar to that at terminal station A and needs no further explanation. Low frequency signals arrivin over the line L1 will be impressed by t 1e transformer T1 upon the .output branch l of the terminal station A. These low frequency signals will be amplified by the amplifier AG and willmodulate y in the modulator M, `the high frequency oscillations set up by the oscillator O1. The modulated oscillations ,when radiated by :the directive array of which antennae X1 is a part will be received by the loop antennai X1', X2, and X3 constituting partfof an array of the repeatingstation C, which are tuned for the reception of oscillations ofthe frequency transmitted by the power oscillator O1. These received oscillations willbe amplified by the amplifier' A1 and ,the currentin each local circuit will be Vadjusted in phase by the phase shifting device PSL so asto retain the proper directional chai'- acteristic of the array. The current will be transmitted through the band filter F, land when amplified by the power amplifier A2 will be transmitted by the transmitting antennae X X2 and XW Thev array of which the latter antennae form a partis designed to direct its energy toward vthe receiving loop X5 of the station B, which is tuned for receiving oscillations of the frequency transmitted b the repeater station. plified by the amplifier A6 `detected by the detector D2, and again amplified .by ,the amplifier A7. The resultant low frequency signals will be impressed .across the'low frequency signaling circuit L2. In similar manner low frequency signals arriving over the line L2 will be transmitted from the station B by the transmittin 'antennae These signals will be relaye by the repeating station() and impresscdupon the terminal station A.

Fig. 9 shows a complete system which dilers from that disclosed in Fig. 8 primarily for the reason that the carrier oscillations, generated at station A, are transmitted together with the side bands to the repeating station@ where both the carrier and the side band frequencies are amplified and are then transmitted lto the terminal station B where the received carrier is used not only for the detection of the received side band frequencies, but it also serves as `the carrier of signal frequency from -station B to station A. At station C, X1 represents a transmitting zantenna of an array and Xl represents a receiving loop of an array. Al represents a low power amplifier and A2 a high power amplier'whose output side is connected with a phase shifting device PS1, which is coupled to the transmitting antenna X1. The receiving loop X, is designed to receive the carrier and side'band frequencies. The received current will be amplified by the amplifier A..I and will be detected by the detector. D1. The resultant The received oscil ations will be am `line L1 at the stationA will be impressed by the transformer T1 upon the output circuit l. These currents will serveto moduv late the high frequency oscillations setup by the oscillator O1- which operates f in con-` junction with the modulator -M1.` `The resultant vside bands of oscillations, together with the carrier, 'will be radiated by the antenna X and will be received b the loop X1 at the relay station. Both t ye carrier and the side band frequencies will be am-` pliiied at the relay station and will be transmitted from the antenna `X1.g kDueto the directive qualities of the array, ofwhich antenna X1 is a unit, the oscillations of the carrier and the side band frequencies will be received at the loop X5 located at station B. Currents of all frequencies will be amplified by the amplifier A4, and the signal frequency will be detected by the detector D2 and impressed upon the line L2. A part of the energ of thev carrier frequency will be transmitted7 to the branch circuit 2 and will be impressed upon the filter F1, which is `designed to transmit the carrier frequency. Current of the carrier frequency will pass through thelilter Fl and will be modulated by the signal frequencies arriving over the line L2 for transmission from the antenna] X5. It will be seen that the arrangement disclosed in Fig. 9 is adapted for the repeating of messages in each direction using the same fre ueney for receiving and transmitting at t e repeating station. Although a particular form of repeating circuit is shown,`

it is to be understood that any forms shown in the preceding figures may be used in the system shown in Fig. 9.

Fig. l0 shows the geographical distribution, for example, of four repeaters located between two terminal stations. Any form of the antenna ma be used for receiving and transmitting. It is necessary only that the direction of reception and transmission shall be Vperpendicular to 'each other so as to avoid singing of the repeaters.

This invention is broadly directed to the combination of repeating circuits with directive antenna arrays. From the foregoing descriptions it will be seen that 'the ob- 'ects, set forth in the beginning, may readily e obtained by the means described and illustrated. Furthermore,y it should be clearly stated that the amplifying circuits are in reality translating circuits capable of modifying the current ina variety of ways apart from amplifying, such as frequency selection by filters and phase control by the phase shifting devices. It is also desirable to make definite that the amplifiers may be either a single `stage or multi-stage arrangeby the transformer T3v ment, and may be ofthe thermionic vacuum tube or otherwell known type.

" It will, of course, be apparent that the invention is not .limited to the particular forms and arrangements shown in the aforedescribed figures, since it is capable ofemloodiment` in a variety of other and different forms Within the spirit and scope of the appended claims.

What is claimed is: l l. In a radio repeating system the combination with an antenna array for the reception and transmission of signals, of `a plurality of amplifiers connected therewith, means to control the phase of the currents `applied tothe antennae of the said array, and means to control the phase of the cur-l rents received from the saidantennee and applied to thesaid amplifiers.

2. In a radio repeating system the com- `bination with'- an antenna array of a plurality Vof repeating circuits individual to jthe antennae of the said array including frequenc selecting means, means to cont-rol the p ase of the currehts` received by `the antennae of the said array and means to control the phase of the currents applied to the antennae of the said array for transmission therefrom.

3. In a radio repeating system the combination `with an antenna array forthe reception and transmission of` signals of a plurality of repeating circuits each individual to an antenna of the said varray and each having its input and its output circuits connected with its respective antenna, and means associated therewith to prevent singing of the said repeating circuits.

4. In a radio repeating-system the comblnation with an antenna array for the reception and transmission of radiant energy of a plurality of local amplifier circuits each individual to and having its input and its output ends connected with one antenna of the said array, the said local circuits having associated therewith devices for controlling the phase of the received and the transmitted energy.

5, In a radio repeating system the combination with a repeating station comprising a directive antenna arra having amplifiers associated therewith or the amplification of signals transmitted thereto of a plurality of terminal circuits adapted to work in conjunction with the said repeating circuit, one of said terminal circuits having a source of carrier oscillations, and having its antennae tuned to transmit carrier oscillations to the second terminal circuit` to be used therein for the purpose of detecting received signals, the said second terminal stationhaving means to utilize a portion of the said carrier oscillations as the carrier of signals to the said first terminal station.

6. In a radio repeating system the coml UU bination with an antenna array comprising a plurality of antennae each for the reception .and transmission of signals, of a plurality `and mear-,1s t0 ,Control the phase 0f the Output current.

8. In a radio repeating system, the combination with an antenna array comprising a plurality of antennzeJ each for the reception and transmission of signals, of a plurality of translating circuits, each having its inputend and its output end conjugately connected with one of said antennae whereby singingof each of said circuits is prevented, and each 0f said Circuits haring an amplifier, means to control the phase of the current applied to the said amplifier, and means to control the phase of the current applied by the saidainpliiier to its antenna.

9. In a radio repeating system, the combination With an antenna array comprising a plurality of antennae each for the reception and transmission of signals, of a plurality of translating circuits, each havlng its input end and its output end conjugately connected with one of said antennae whereby Vsinging of each of said circuitsis prevented,

cluding one of saidl amplifiers to connect the iii-ppi side andthe .Output side .of ,its amplfier with the antenna with which the4 said amplifier ,is intend ip cooperate 11- In a .radio repeating system, the ,6,0mbinationv with a plurality of consiiiuiing an array for the transmission spd reception 0f signals, 0f s plurality 0f amplifiers having input and. ppfpili Cifsuts, each cooperating with one of the said antennae, a plurality of coupling means each connested with Qns 0f said antenas@ spd also with the said input and Ontpnl circuits of the amplifier @Oppsfptng wif3 .the same antenna, the said coupling means being so designed and the connections being so effectedY that theoutput Ycurrents produce no effect upon the input circuit and likewise the input current no effect uponl the output circuit. i

In testimony whereof, we have signed Our names t0 this spifiltpp this 27th dei of December, 1921. t

LLLQYD EsBENscHiED- DE Loss K. MARTJIN.

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