US2444425A

US2444425A - Antenna array

Info

Publication number: US2444425A
Application number: US497890A
Authority: US
Inventors: Henri G Busignies
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC; Federal Telephone and Radio Corp
Priority date: 1943-08-09
Filing date: 1943-08-09
Publication date: 1948-07-06
Anticipated expiration: 1965-07-06

Description

s m N m S u B G H.

July 6, E4.

Y m A N N E T N A 8 Sheets-Sheet 1 Filed Aug. 9, 1943 PHASE C'MOL Riff/VER TIM/Fu lof/H3 E CONT/ml (2@ INVENToR. Hf/VF/ G. 50S/@NMS BY TTRVEY Juy 65, g4, H, G, BUSIGNlEs 2,444,425

ANTENNA ARRAY Filed Aug. 9, 1943 8 Sheets-Sheet 2 ,71.2 awe@ oF H6, I.

IN VEN TOR. IIE/WPI 6. 805/611056 A TTHNEY MY @y 1948. H. G. EUSIGNIES 2,444,425

4ANTENNA ARRAY IN VEN TOR. r "7-` HfA//P/ G. 50s/GMES /1 TTOHNE' 8 Sheets-Sheet 4.

ANTENNA ARRAY H. G. BUSIGNIES Filed Aug. 9. 194s I N V EN TOR. HENR/ G. BUS/GMES ATT//VEY July 1948. H. G. auslGNlEs ANTENNA ARRAY INVENTOR. Hfwe/ G. aas/@Mes :216

my 6 1948 H. G. BuslGNlEs ANTENNA ARRAY 8 Sheets-Sheet 6 Filed Aug.' 9, 1943 MY 6, 1948. H. G. BuslGNlEs 2,444,425

ANTENNA Amr Filed Aug. 9. 1943 8 Sheets-Sheet '7 l Vinili/TIERS INVENTOR. MEW/Pl G. BUS/GAMES H. G. BuslGNlEs 2,4

ANTENNA ARRAY Filed Aug. 9, 1943 8 Sheets-Sheet 8 IN VEN TOR. ,ww/W 6. axs/Gw/e's determined desired conditions Patented July 6,1

UNITE Nes t Telephone and t i N. 3., a corporation oi- Delaware olii Corporation,

Application somt aises. serial no. coarse (ci. ses-115) 2@ Claims.

This invention relates to radio antennas and in particular to directive antenna arrays and assoelated apparatus whereby the directivity of the arrays may be controlled in accordance with pre- I or requirements. 'The objects of my invention are:

To provide a single antenna array and associated apparatus capable oi? simultaneously re ceiving a plurality o1 radio transmissions either of the same or of different frequencies from diderent directions.

To provide a single antenna array and associated apparatus capable oi simultaneously receiving a plurality oi radio transmissions of dierent frequencies from any one given direction.

To provide a circular antenna array and asso- -ciated control apparatus by which radio transmissions i'rom any direction in azimuth may be received.

To provide a circular antenna array and assoelated control apparatus by which the directivity of the array may be rotated in, the horizontal plane at substantially any rate.

To provide a completely .automatic direction finder capable of determining the direction of a radio transmission in the horizontal plane.

To provide a voltage operated phase changer by which the phase of a voltage or current wave may be advanced or retarded through 360 electrical degrees.`

To provide a voltage operated phase changer and control apparatus therefor by whichl the phase and magnitude ci a voltage or current wave may be changed in accordance with a given cycle.

These and other objects and features will be come apparent from the following description taken in connection with the attached drawings illustrating several embodiments of my invention, and wherein A Fig. 1 is a schematic circuit diagram showing an antenna array and associated circuits in accordance with one embodiment of my invention;

Fig. 2 is a schematic diagram illustrating a voltage operated phase changerin accordance with my invention:

Fig. 3 is a diagram illustrating one ymethod for determining an antenna array in accordance with my invention;

F154 is a vector diagram illustrating the magnitude and phase relations of voltages which may be obtained from the phase changer shown in Fig. 1'

Fig. 5 is a second embodiment of my 4invention wherein a plurality of ar'itennas'V are arranged in circular array;

Fig.y 6 represents the field pattern ofthe array resulting from a given predetermined set of conditions shown in Fis. 5

o I l Fig. 'I is a polar diagram used in explaining the principles of my invention; i

Figs. 8 and 9. illustrate respectively the phase and magnitude relations of currents delivered to the transmission lines shown in the antenna array of Fig. 5;

Fig. i0 is a schematic diagram of e, phase control device for controlling the phase changer ci.'

. .rig a; and

lil

Fig. 11 is a sectional diriga-...ilV of the phase control device as viewed from the section line ii--i i of Fig. 10.

Referring to Fig. l I have schematically iiius trated a six-element linear antenna array togather with receiving apparatus and contro! equipment suitable for receiving a, plurality of radio transmissions from different directions as set forth in the first two objects of my invention. In the figure, elements i-i represent six antennas arranged in linear array. These antennas are preferably aperiodic and therefore are capable ol substantially equal response over a wide irequency band. Connected across an. impedance in each antenna are two phase changing devices shown as ,blocks Bland iii. Each block represents apparatus for changing the magnitude and phase of the voltage induced in the antenna circuit. The specic circuits for the phase changing dee vices are illustrated in Fig. @ne set of phase changers, represented by .reference characters ior example, is for detemninin the elci pattern oi the antenna array for one particular frequency. The other set of phase changers, it. are for deter-- mining the held pattern for another .frequency which may have a maximum dircctivity either in the same or in a dierent direction from that determined by the phase changers ii. It is to be understood that whereas I have illustrated only two groups of phase changers, any number of groups may lbe employed each group acting entirely inde pendently from the others and determining a separate eld pattern. Extending from the -phase changers il are a plurality of transmission lines I2. Each line extends from the phase changer to which it is connected at one end to a receiver I4 which may be located at a remote point. The output impedance of the phase changer is matched to the impedance of the line. In the interest of economy of transmission lines it is preferable that adjacent lines, for example those associated with antennas i and 2, be connected together at a point Iiiv and that the combined energies from these lines be transmitted over a single line i8 to receiver it. The dimensions of the lines are preferably so chosen that an impedance match occurs at the junction point i8. It is preferable though not essential that the elecand all oi the In a similar manner, transmistrical length of all of the lines i2 lines I8 be equal.

e cathode follower phase invertor type.

3 sion lines 20 extending from phase changera i0 are connected together at point 22 and the ener- `gies therein are transmitted over a common line 20 to a. separate receiver 20.

Associated with receivers I and 26 are phase change control devices 20 and 00 respectively.

, Control channels 3|30 extend from the phase control device 28 tothe phase changers 0. In a. similar manner control channels 31-02 extend .from the phase control device 00 to the group of phase changers I0. Each control channel, 3iy for example, is to be considered as representing a number of conductors sufilcient to control the l operation of a single lphase changer.

In general the phase changers, as illustrated by the schematic wiring diagram of Fig. 2, comprise a plurality of vacuum tube amplifiers oi the I have illustrated each phase changer as comprising three ampliiiers A, B, and C. The input circuits of the amplifiers are connected in parallel across an impedance 50 in the antenna circuit of each of the antennas |6. Between the point 5| and the control grids I52, 53 and 50 of ampllers A, B, and C respectively. there is a connection having electrical characteristics such that the voltthe point 5| to the grid 53 there is an inductive reactive connection. Any voltage occurring on grid 53 as a result of an applied voltage at point 5|, therefore undergoes a lagging phase shift. Similarly, a capacitive reactance is connected between the point 5i and the grid 00 whereby any voltage occurring on the latter grid, as the result of a voltage applied to the point 5|, undergoes a leading phase shift. The inductive and capacitive reactive connections are represented by the inductor 56 and the capacitor 50. Shouti ing the inductor 56 is a variable resistance 00 by which the phase voltage and the grid 00 may be controlled over a predetermined range. Similarly, a variable resistance 62 is shunted across the capacitor for varying the phase of the voltage and the grid 54. `It is to he understood that the

reactors

50 and 50 may also be made variable for producing phase variations of voltage on the grid to which they are connected.

Between the cathode 60 of amplier A and ground, there is a resistor 60. The voltage oleveloped across this resistor is in phase with the voltage appearing across the resistor 50 in. the

' antenna circuit. A lead 68 connected to the junction point between the cathode 60 and the resistor 6B has a voltage impressed thereon having a phase relation the same as that across the resistor 65. Between'the anode ill of amplifier A and ground, there is a second resistor l2, and across this resistor a voltage is developed having a 180 phase relation with respect to the voltage impressed across the resistor 50 in the antenna circuit. A lead 14 connected to the Junc- ,tion point of the anode l0 with resistor 'i2 has the same phase as that developed across resistor 12. It will therefore be seen that the voltages developed across conductors 00 and 10 have a 100 phase relation with respect to ground. The magnitude of this voltage is controlled'in part by the value of the voltage appearing on grid 10, and the source of this controlling voltage is in the phhse control device 20. A conductor 'l0 extends between the grid l0 and the phase control device 20, and is one of the conductors making up the channel 3| described in connection with Fig. 1. A'second conductor 80 extends between the anode 10 and the phase control device 20 and is for the purpose oi' impressing a positive potential on the anode. A choke coil 02 prevents radio frequency currents from flowing in the conductor 00. The conductor 00 represents another of the conductors constituting the plurality of conductors of channel 3|. The magnitude of the voltage applied to theanode also controls the magnitude of the voltage appearing across the conductors 00 and 14. The capacitor lay-passes the radio frequency current to ground and blocks direct current from the conductor 00 from ground.

Referring now to amplifier B, the resistor is connected between the cathode 92 and ground. The resistor 00 is connected between theV anode 00 and ground. The phase relation between conductor 00 and ground and the conductor-'|00 and ground is as will be seen from the description in connection with amplifier A. The phase relation between the voltage appearing across the conductors 00 and 'le and the voltage appearing across the conductors 00 and |00 will have a substantially 60 phase relation as determined. by the reactor The magniturleoi the voltage across conductors 00 and. i00 .is determined by the voltage appearing on the grid lili: and the anode 06. The arid voltage is impressed from the phase control device 20 to the grid |02 over the line |00 which constitutes part of the channel 3|. I'he anode voltage is transmitted over` the line |06 extend .ing between the anode 00 and the phase control device 20 and this line |06 likewise constitutes part of the channel 0 I.

With respect to amplifier C, the phase relation hete/een the voltage across conductor |00 and 'ground d the voltage across conductor |-|0 and ground la 300. However, due to the reactor 00.

the voltage between conductors |00 and ||0 is4 displaced substantially 60" from the phase of the voltage across conductors 00 and 10. 'The magnitude of the voltage between conductors |08 and lill is determined by the voltages applied to the grid iii?. and the anode lit of amplifier C. The voltages are impressed over lines Il and IIB respectively from the phase change control device 20. Lines im and H0 constitute conductors of the control channel 3l. It will be seen that in the illustrated case, the control channel 3| cofmprises six conductors i8, 00, |00, |06, H6, and H0.

The output conductors 08 and 14 of amplifier A are connected to the output conductors 90 and |00 of amplifier B and to the output conductors of |00 and @i0 of amplier C at the points. |120 and |22 in such a manner that the phase relation of the voltages appearing across points |20 and |22 due to the above mentioned conductors are apart. This phase relation 'may be obtained by inverting the phase of the voltages across conductors 93 and |00 and across |08 and ||0 with respect to the points H20 and |22. Under these conditions, if the voltage appearing across each of the resistors 50, i2, 00, 00, |20 and |30 were equal in magnitude, the combined voltage across points |20 and |22 would be zero. However, if a. voltage appearing across any of the resistors inmediately above mentioned was reduced or increased', the voltage across points |20 and i22 would no longer be zero, but would have a iinite value and phase relation dependent upon the magnitude of the voltages appearing across the resistors. Connected across points i2lll and |22 are the lines l2 or 20 of, Fig. 1 as the case may be.

Referring again to Fig. 1 it 'will be seen that due to the common connections at points Mil and M2 of the lines I8 of which the lines I2 may be considered as branches, a change of voltage across any or the resistors in any of the amplifiers of the phase changers 8 will result in a. change in magnitude and phase of the final voltage impressed upon the receiver i4. Likewise when considering phase changers lll, a change in voltage appearing across any resistor therein will aiect the magnitude and phase ultimately impressed upon receii -r 26. However, there is no interaction between phase changers 8 and In and theredore each receiver will be controlled by the respective phase changers to which it is connected.

In Fig. 3 I have shown the manner in which a single antenna. array may be designed to receive vradio transmissions from two arbitrary directions in such a manner that the iield patterns of the antenna array will be a maximum in the direction from which the transmissions are received. It two diierent frequencies are being received the directivities of each transmission may be the same and there will be no interaction. If the radio transmissions are of the same frequency, in order to prevent interaction of the receivers it will be necessary for the transmissions to have different directions with respect to the antenna array. I have assumed two transmitters located at points S1 and Se and a receiver located-at-R. The angle .between the transmissions from Si and Sz with respect to R is There are many types of arrays known to the prior art and I have chosen the type known as a binomial array for describing my invention. .at right angles to the direction of transmissions from S1 a six-element binomial array is laid out. As is well known the spacing between the antennas of the array are one-half wavelength at the operating frequency which I have designated in Fig. 3 as The relative lmagnitudes of the voltage outputs from the wave changers associated with each antenna are 1-5-10-1051 sequentially between end antennas of the array. It is of course understood that a one-half wavelength separation is equivalent to a 180 time phase displacement. Construction lines are drawn parallel to the transmissions from S1 through the antennas of the array. A similar array is constructed at right angles to the transmissions from S2 and the distance between the antennas are designated Through the antennas of the second array, construction lines are drawn parallel to the transmissions from Sz. At points where the two sets of construction lines intersect, the antenna array comprising antennas l-2--3- t--E-ti in accordance with my invention may ,be positioned as shown in Fig. 3. It will be seen. that projections from the antennas to assenso points on a line at right angles to either directie of transmission will be equal to one-half tb wavelength of either transmission.

' Considering transmissions from S1 for exampl it will be observed that there will be a difieren( in phase between the energies arriving at tt various antennas o the array, and that this phat relation for a given wavelength is dependent upc the angle ebetween the array and the direction l reception. This angle I have designated 0 an the phase between the energies induced in an two adjacent antennas is equal to 1r cot 0 radlan In order that the antenna array will have field pattern with a maximum directivity in tr direction of S1, it is required that the effectii outputs of wave changers associated with ti antennas be cophasal. This result may be ai tained as follows:

A wave front passing through the array will ir tercept the antenna closest to the transmitter certain number of electrical degrees in spal phase before intercepting the second antenn If the .iective output voltage from a pha: changer associated with the first antenna is dl layed an amount equal to this space phase, ti eiect upon a receiver would be the same as the receiver were being acted upon by in-pha: voltages from both antennas. Applying th principle to all of the antennas of the array, will be seen that by a plurality of suitable pha: changing means, the eflective output voltagn from all antennas can be made cophasal.

In Fig. l I have illustrated by a group of vel tors, certain conditions which must prevail i order that the antenna array ofFig. 3 have tl desired maximum directivity in direction S1 fro: the receiver R. The angle 0 between the arr: and the direction of reception is assumed to l The vector Ve represents the output voltar from the phase changer associated with antenz 6. Vs represents in magnitude and phase tl value of the output voltage from the wa changer associated with antenna 5. The pha relation of the voltage induced in antenna 5 wii respect to that induced in antenna 5 is 104 represented by the angle between Vs and Vs. Th means that the phase changer associated wi antenna 5 must advance the phase of the inpi voltage by 104 in order that the outputs of tl two phase changers will be cophasal. A simili analysis applies to all of the remaining vecto V4, V3, V2 and V1. A detailed example of tl manner in which the phase changers operate provide an output of the desired magnitude ar phase will be given hereinafter in connection wi1 a second embodiment of my invention.

Although I have described my invention 1 embodied in the diagram of Fig. 3 as comprisii an antenna having a directivity in two directior it is to be understood that any number of dire tivities could be obtained provided only that tl distance between adjacent antennas is substai tially equal to the operating wavelength divldr by twice the sine of the angle between the dire tion in which the antenna array extends ai the direction of reception. This distance shown in Fig. 3 as The directivity can therefore be varied over considerable angle without materially aiiectii the field pattern of the antenna array.

Referring to Fig. 5 I have illustrated anoth` embodiment of my invention wherein a plurali -phase changer of the type illustrated in Fig. 2 and from each wave changer a transmission line extends to a central receiver. At any instant oi time a predetermined number of the antennas are conditioned through the medium of their associated phase changers so that as a group they are responsive to radio transmissions from a predetermined direction -and substantially nonrespo'nsive to transmissions from other directions. Even though the antennas constitute a receiving array, the antenna may be said to have a eld pattern having a maximum directivity in a predetermined direction.

In accordance with my invention the ileld pattern of the directive -array is rotated in azimuth. The rate of rotation may have substantially any value, being determined in accordance with my invention by the rate of rotation of a mechanical phase control device to be hereinafter described. The rotation of the eld pattern is accomplished by progressively energizing -antennas on one side of the group which is active at any given moment and cie-energizing antennas on the other side of this group.

In order to describe my invention, it is convenient to discuss a given antenna array which is conditioned to receive in accordance with a predetermined field pattern. For example in Fig. 5

-I have illustrated an outer antenna array in which fifteen equally spaced antennas are positioned on the circumference of a circle having a radius of 432 electrical degrees and an inner antenn'a array positioned on the circumference of a circle having a radius of 340 electrical degrees. One antenna of each array is positioned on a common radius. Adjacent antennas of the array are spaced 24 electrical degrees apart. Considering for the moment the outer array, the adj-acent antennas thereof are spaced apart one-half wavelength at the operating frequency or 180 electrical degrees. It is from this given condition that the radius of the array equals 432 degrees.

In Fig. 5 I have not shown all of the antennas constituting the complete array, since so doing `would merely complicate the drawing and add nothing to a clear understanding of the operation of my invention. I have assigned reference characters Ai-Ae to `a group of antennas in the outer arrayand Aff-A12 to a group of antennas in the inner array. A discussion of the manner in which these antennas and their associated wave changers are conditioned to operate will be suiiicient to completely describe the operation of the system as a whole. Opposite each antenna I have indicated certain voltage values and phase relations to be used in describing its operation. As-

i suming the direction of maximum reception is rotating'in the direction of arrow Da the upper values indicate certain voltage and phase relations when the antenna array is conditioned to receive from the direction of the arrow D1 and the lower values indicate conditions when the array is conditioned to receive from the direction D2. The amplitude and phase relations of the voltages d elivered from the phase changers of the array gradually shift from one set of values to the other as the directivity of the array changes from the direction of Di to Dz as will be hereinafter more completely described. When the array is receiving from the direction Di, the phase changer associated with antenna As is delivering a maximum voltage E having a phase relation of zero degrees taken as a reference. Phase changers associated it with antennas A2 and A4 on either side of A: are conditioned to deliver a voltage of .67E having a phase relation of 37.2. Similarly, phase changers associated with antennas A1 and A5 are conditioned to deliver a voltage of .167E having a phase relation of 143. It will be observed that the values .167-.67-1-.67-.16'7 bear the relation of 1-4-6-4-1 respectively, and that these values represent magnitudes corresponding to the effective received voltages in a binomial array of live antennas. As above described in 'connection with Fig. 3, in order that an antenna array have a maximum directivity in a direction normal to the array, it is necessary that the effective voltages f delivered from the antennas have a cophasal re- Since the antennas of my array are on lation. the arc of a circle, it is necessary that means be provided in the form of a phase changer to develop these cophasal voltages. For example, in order that antenna Az deliver a voltage in phase with antenna A3, the phase changer associated with A2 must advance the phase of the voltage wave as it strikes the antenna by 37.2. Similarly, the phase changer associated with antenna A1 mustadvance the phase of the voltage wave intercepting the antenna by 143.

As is known in the prior art. in order that an antenna array have a unidirectional receiving pattern with a maximum directivity normal to the array, it is customary to provide either a second array of reflecting antennas usually spaced onequarter wavelength from the energized antennas' or to provide means for energizing this second array. .Due to the fact that the antennas of my invention are aperiodic, it is necessary to provide a second energized array rather than one of the unenergized or reflector type. Accordingly, a second group of antennas Ar-Aiz is provided to form an inner array.- Since the antennas of the arrays are on the arcs of circles, it is impossible to locate all antennas of the inner array so that they will be one-quarter wavelength from corresponding antennas in the outer array. However, the antennas of the inner array may be conditioned to deliver a voltage wave having a phase relation such that substantially the same efl'ect is obtained as if the one-quarter wave phase relation existed.

The values of the voltages and phase relations delivered by the output of antennas Arf-A12 is recorded in Fig. 5.

The above discussion has dealt with the magnitudesl and phase relations of voltages delivered by the antennas under consideration when max-l imum reception is from the direction D1. If now the various magnitudes and phase relations of all the antennas be changed in a manner such that they correspond to the lower sets of figures shown adjacent the various antennas, the antenna array as a whole Will have a field pattern such that its maximum directivity is in the direction D2. An examination of the drawing will show that under these conditions antennas A: and A4 for example will deliver equal voltages of .89E having a phase relation of 9.5. The antennas of a binomial arrayunder these conditions would normally have sequential voltage values of 1-5-10-10-.5-1. However, since the outer antennas of a six-element array deliver only nl; of the total voltage developed by the array and the power varies with the square of the voltage, these outer antennas have been disregarded in the computation. By so doing no 'serious error could be noted in any practical system. For this reason the magnitudes of voltages delivered by antennas A1, As, A1, and A12, have been considered as zero. The

phase relation however of these voltages has been recorded to indicate the phase relation at which voltages would begin to be developed by these antennas during the rotation of the field pattern. The field pattern for the condition in which antennas .A2-A5 of the outer array and antennas Aia-A11 of the inner array are conditioned for receptionior the direction De has been computed and is shown on the polar diagram of Fig. 6. It will be seen from this diagram that the field pattern has a very marked directivity in the direction Da.

Y I will now describe the manner in which the phase changers are operated so as to deliver output voltages having a desired magnitude and phase in accordance with the conditions indicated on-Fig. 5. In Fig. 7 are plotted two curves M and N from the voltage and phase values appearing on Fig. 5. Curve M shows the order of change of the voltage and phase delivered by a phase changer associated with any antenna in the outer array. Curve N shows similar values for a phase changer'associated with any antenna of the inner array. These curves are substantially two spirals having a 90 phase relation therebetween: A discussion of the variation in magnitude and phase of voltages from -antennas in the outer array only willbe given in order to not unduly lengthen the specification and since a similar discussion would apply to antennas of the inner array.

In Fig. 7 I have shown a plurality of vectors extending from the origin to certain points on curve M, these vectors representing the specific values of magnitude and phase of voltages appearing on Fig. 5. Curve M is interpreted as follows Whenthe directivity of the array changes from D1 to Dz, the magnitude and phase relation of the output voltage from antenna n as represented by vector V7 changes to a value represented by vector V8. At the same time the magnitude and phase relation of output voltages from antenna Az changes from a value represented by vector Vc to a value represented by vector V10, and likewise the output from antenna A1 changes from vector V11 to zero. It will be observed that during this period there is considerable reduction in magnitude and an increase in phase diderence in the voltage outputs from antennas A3, A2, and A1. On the other hand, the output from antenna A4 'increasesro-rn a value represented by vectorVo to a value represented by" vector Va, while the output from vantenna As increases from the value represented by vector V11 to the value represented -by vector V10. It is clear that the changes in output just described occur While the drectivity is changing from the direction D1 to the direction D2 or through` 12. The manner in which the magnitude and phase of the output voltage from any antenna changes through one complete rotation of the eld pattern is shown on Figs. 8 and 9 respectively for that portion of the complete cycle cluring which any given antenna is conditioned to receive. In Fig. 8 curve 20d shows a variation in phase through which the output of any antenna of the outer array passes during 'a 120 rotation of the held pattern. Curve 2li-2 shows the change in phase through which the voltage output from any antenna oi the inner array passes during the same period.

The phase changer which is associated With any of the antennas of the arrays, is shown in Fig.l 2 and has been previously described. The manner in which the output of the phase changer is controlled so that it will deliver a variable voltage having a variable phase in accordance with the reduirements of any antenna `shown in Fig. 5 will now be described. First, from the wave changer associated with each antenna of the outer antenna array, there extends a -transmission line 220 to a central receiver. Preferably these transmission lines are of equal length and have the same electrical characteristics. Other similar transmission lines 222 ex tend between the phase changers associated with the various antennas of the inner array and the central receiver. These latter transmission lines should also be of equal length and electrical characteristic, but need not necessarily be equal to the first group oi transrnissifm.l lines 220. Each transmission line has been diagrammatically illustrated in Fig. 5 as a single conductor. In reality the line is preferably composed oi two conductors extending from the points 12D and E22 in Fig. 2.

In Fig. 5, as well as Fig. l, I have illustrated each phase changer unit as being connected directly with its associated antenna., and have also illustrated a transmission line extended from the phase changer to the receiver. It is to be clearly understood that each antenna could be first coupled to a transmission line with the far end of the line connected with a phase changer unit. Under these conditions all the phase changers could be centrally located at the receiver. If this type ofconstruction were employed it would of course, be desirable to match the output impedance of the antenna with the input impedance of the transmission line and the output impedance of the transmission line with the input impedance of the phase changer in accordance with known methods.

Also extending between each phase changer and a phase control device is a control channel. Each channel. is diagrammatieally illustrated in Fig. 5 as a line 230. Each line` is actually coin posed of a plurality of conductors and as shown in Fig'. 2 these conductors are identified by reference numerals lil, Sil, itil, iilii, lili, iiil. The phase control device 232 is preferably located adjacent the central receiver but in Fig. 5 it has been drawn at the top of the iigure in order to maire the diagram less confusing. lt is the function of the phase control device to apply voltages to the various grids Mit, and lil of the ainpliers shown 2 or" such magnitude that the output voltage from the combined amplifiers as it e nears across ternurnals i2@ and iti: will have t-.. desired amplitude and phase. ,es an example when the output from antenna As has an amplitude ci E and phase zero, iet it be required to produce an output voltage from A2 of a magnitude .67E vand phase of 37.2.

Considering Figs. 2 and 7 the output of ampliiier A varies in accordance with a vector en tending from the origin horizontally to the right along a line This line represents the refer-A ence from which all phases are measured. The line 2&2 positioned in the 2nd quadrant of the diagram of Fig. l is that along which the vol-- tage output from amplier E varies. This line bears an angular relation with respect to line 2d@ of approximately 127 in accordance with this example and for a reason which will be brought out later. This angle of 127 is determined by the reactor 5e in the grid circuit of amplifier B and the polarity in which the output leads 96 and |00 are connected to points i2@ and |22. 1n

antenna arrays.

asta/.tac

the third quadrant n line 2M extends in n, direction havingr an angular relation with line 21m of 216 for reasons which will be described later. It is along this line that the vector of the voltage output from amplifier C extends. The direction oi' line 2M is determined by the capacitor 5a and the polarity in which the output leads Iil and liu are connected to points 12u and i22.

-Digressing for the moment from the particular problem at hand, it will be noted that if the volt'- ages applied to the grids |02 and I i2 of ampli- -iiers B' and C respectively were such that a current output from these amplifiers were reduced to zero. the vector output from the complete phase changer would be determined solely by the output from amplifier A. The vectors normally extending along the lines 2M and 2M would be reduced to zero, and the output vector from amplifier A would lie on line 240. The magnitude of this vector could be determined by the voltage applied to the grid 18 and to the anode l0. As a matter of fact the output vector from antenna A1 extends along this line. and may be represented by the vector V7. At the same instant of `time it is desired that the output from antenna A: have a magnitude of .67E and a phase relation o1' 37.2, as shown by vector V2. This vector may be obtained by reducing the voltage on the grid 18 of amplifier A to a value where the output is represented by vector V12 while at the same time increasing the voltage applied to the grid |02 of amplifier B until the output from this ain-v pller may be represented by the vector V13. The output from amplifier C is maintained zero during this time. The sum of vectors V12 and V13 is equal to the desired vector Vo.

At this same instant the output voltage from antenna A1 should have a value of .167E and a phase relation of 143. This voltage is shown by vector V11 and may be obtained by reducing the output from amplifier A to zero, and maintaining outputs from amplifiers B and C equal to values shown by vectors V14 and V15 respectively. In s. similar manner the desired amplitude and phase relation of any voltage of any antenna of the array may be obtained.-

The manner in which the direct current voltages to be impressed on the grids 16, m2, H2, and amplifiers A, B and C respectively may be generated is illustrated in Figs, 1() and 11. In these figures I have represented a plurality of variable capacitors. Each capacitor comprises two electrodes, one fixed and one rotatable. One of these variable capacitors is provided 'for each phase control grid electrode controlling the output of an ampliiier in all phase changers. In the present illustration there would thus be a total oi' 90 capacitors, three for each phase changer of which there is one for each of the thirty antennas comprising the inner and outer However, I have illustrated in Figs. and 11 only forty-five of these variable capacitors or a number sufiicient to control the outputs of the antennas constituting one of the circular arrays. It is understood that the other forty-five variable capacitors for the other array would be similar to those illustrated in Figs. l0 and 11. As illustrated by these figures the fortyfive fixed electrodes of the variable capacitors are divided into groups of 15, each group lying on the periphery of-a circle. I have designated these groups as X, Y and Z. Associated with groups X, Y and Z are three rotating electrodes X', Y and Z' respectively. The rotating electrodes may be likened to cams having predetermined irregular pliier C of the phase changers. served that the fixed electrodes of group X are iig incre-fi as shown in iilg. 10. As the electrodes X', Y' and E' rotate, it will be seen that the interelectrode capacitance between the surfaces oi the rotating electrodes and the fixed electrodes changes due to the irregular shape of the former.

The fixed electrodes Xi-Xn are connected to the phase control grids 16 oi.' the amplifiers A associated with the phase changers in the outer antenna array. Similarly, each xed electrode Yifir. of group Y is associated with the phase control grid m2 of' amplier B of these phase changers and fixed electrodes Zi-Zin of group Z are connected to phase control grids |12 oi am- It will be obco'nnected to that amplifier A whose output is in phase with its input, that the electrodes of group Y are connected to that amplifier having an inductive reactance in its input circuit, and that the electrodes of group Z are connected to that amplifier having a capacitive reactance in its input circuit.

In the lead between each fixed electrode in groups X, Y, Z and a phase control grid in the phase changer, there is a vacuum tube rectifier D. shown in Figs. 10 and 11 these rectiers may consist of atriocle in which case an amplifying as well as a detecting action is obtained. It is to be understood that any equivalent rectifying device such as a diode or a selenium rectifier may be employed.

A source of high frequency current 250 is connected between the rotating electrodes X', Y' Z and ground through the medium oi. a brush 252 bearing on a ring 251i the latter being a part of or electrically connected to the rotating electrodes. The circuit 256, tuned to the frequency ci.' the source and comprising a capacitor 258 and inductor '260, acts as a tank circuit connected across the output of the high frequency source to improve the regulation thereof. The frequency of the source 250 should be high enough to make the capacitance reactance between the rotating electrodes and any fixed electrode relatively low. SuiHcient energy may thereby the transferred to the rectiiiers to cause them to operate eiilciently. The rectified output of the rectifiers is passed over the control circuits, 18, |04 and |18 for exampie. and impressed on the phase control grids of the phase changer amplifiers. Referring again to Fig. i it will be observed that the vector Vv and therefore the output of amplier A has a magnitude for a portion of the operative cycle at least, greater than the outputs of either amplifiers B or C at any time. This means that the capaci'- tance between the rotating electrode associated therewith X and any fixed electrode X1-X15, must be proportionately greater than the capacitance between either of the other rotating electrodes and their corresponding fixed electrodes. This is illustrated in Fig. 10 wherein Athe rotating electrode X has a relatively long electrode surface opposite the fixed electrodes. Referring to Fia. 7 it was mentioned that the line 242 was positioned at an angle of approximately 127 from the line 2da. This line 'M2 was drawn parallel to the tangent of curve M at the point As'. By such a construction it is seen that the vector V1 undei-goes no abrupt change in magnitude as it rotates from point Aa. This in turnimeans that the periphery of rotating electrode X' has the form oi a smooth curve and facilitates its design. For similar reasons the line 244 of Fig. 'I occupies the position of 216 with respect toline 260, and the electrode Z' may have a smooth outer periphery.

With the electrode X' in the position as shown in Figs. and 11, it will be seen that the reactance between it and electrodes X3 is a minimum, whereas the reactance between electrodes Y', Z', and Ya Z3 respectively is a maximum. This means that only amplier A-of the phase changer associated with electrodes Xs. Ya, and Za is delivering an appreciable output voltage. The high reactance between electrodes Y', Z and Ya Z3 respectively prevents energy iiow from the source 250 across these electrodes with the resultfthat the phase control grids of ampliers B and C of the phase changer are biased to cutoff.

However during this period, the reactance between Y' and the two fixed electrodes Ys and Y4 is a minimum, maximum energy is being passed between these electrodes, andthe result is that the phase of the output ci adjacent antennas is controlled primarily thereby. It must be kept in mind, however, that the voltage output and phase from any antenna is, in general, controlled by the joint action of all energies passing between the rotating electrodes and any group of fixed electrodes X2, Y2, and Z2 for example. As the electrodes X', Y', and Z' rotate, they come into operating relation with other groups of fixed electrodes than those shown in Fig. 10 and in this manner the eld pattern of the antenna array is rotated.

The-manner in which the output from the receiver may be employed to indicate the direction from which a signal is being transmitted will now be explained. The receiver itself may be of any usual type, for example a superheterodyne employing the usual tuned circuits for selecting the frequency to be received. The output from the receiver is connected to the rotating coils 210, 212 of a cathode ray indicator 214 as illustrated in' Fig, 11. The coils of the oscillograph are driven in synchronism with the rotating electrodes of the phase control device. This is illustrated in Fig. 11 by the lines 216, and 213 connecting the motor 280 to the shaft 282 of the phase control device and to the indicator 2li.

Normally, when no signal is being received, a lluorescent spot will appear at the center of the oscillograph screen, the position of this spot being controlled by known means. When a signal is being received, current from the receiver passes through the

coils

210 and 272 causing the spot to trace on the screen a pattern corresponding substantially to the field pattern of the antenna as shown by the curve 204. From the position of the trace with respect to a scale (not shown) on the indicator, the direction from whichrthe received energy is being transmitted can be observed.

In describing my invention I have chosen specie examples of antenna arrays comprising a given number of antennas. The dimensions of the arrays were also assumed. It is to be clearly understood that these values were assumed for the purpose of illustration and description only since other arrays having a'greater or a lesser number of antennas could equally well have been described. In describing the phase changer and phase change control device it has been assumed that the various values of voltage output were controlled by applying suitable voltages to the phase control grids of the ampliers. .These output voltages could also have been controlled in part by applying suitable voltages to the anodes lill of the amplifiers as taught in my copendlng application Serial Number 481,760 rlled April 3, 1943 which issued January 27, 1948 as Patent No. 2,434,904. Likewise in place oi' balanced transmission lines extending between the phase changers and the receivers I could have employed unbalanced lines such as the concentric conductor lines disclosed in the abovemamed copending application. The above description was made by way of example only, and is not to be considered as a limitation on the scope ci my invention as set forthvin the objects thereof and the accomg panying claims.

I claim:

1. A radio receiving system having a directivity variable in azimuth, comprising a plurality of antennas arranged in a predetermined array, a receiver, coupling means connected between said antennas and said receiver, said coupling means comprising a like plurality ci phase changers and a plurality ci transmission iines, each an tenna being coupled to said receiver through one of said phase changers and through said transmission lines, each of said phase changers being controllably adapted to deliver voltages of a selected magnitude and phase, and a. control device connected to said phase changers applying a varying control to said phase changers so that said phase changers deliver voltages of varying magnitude and phase to said receiver.

2. A radio receiving system in accordance with claim 1 wherein said plurality or" rinteimas are aperiodic and are arranged in e,

3. A radio receiving system accordance with claim l wherein said plura ci antennas are aperloclic and are arranged circular array.

A radio .receiving system scorda-nce with claim 1 wherein each of said phase changers coma prises a plural-ity of vacuum tube ampliiiers, each amplifier having an input and an output circuit, the phase relation between the voltages of the input and the output circuits oi one amplifier being different irom the phase relation between the voltages of the input and output circuits of another of said amplifiers.

5. A radio receiving system according to claim l wherein each of said phase changers comprises a plurality of vacuum tube amplifiers. each amplilei comprising an input and an, output circuit and a control grid. said control grid being con nected to said input circuit, connection means for supplying voltage from one oir' said antennas to each of said input circuits, the input circuit of one of said ampliiers having a reactance differont from the reactance of the input circuit of another oi said amplifiers, the maximum phase dii-ference between a voltage developed on one of said grids and a voltage developed on another of said grids being less i530, and circuit connections between the output ci"cuits of said ampliiiers to provide output voltages having a minimum phase diierencc greater than 6. A phase changer for changing the magnitude of a voltage and simultaneously changing the phase of said voltage through any angle between 0 and 360 comprising plurality of vacuum tube ampliers each amplifier comprising an input and an output circuit, an input control grid and a phase control grid, reactive means connecting the input control grids of said ampliers to said input circuit to provide from a given input voltage a plurality of voltages having a maximum phase difference of less than at said input control grids, circuit connections inl said output circuits to provide voltages developed amasar! in said output circuits have a maximum phase difference greater than 180 and control means connected with said phase control grid for'applying a variable voltage to said phase control grid.

'7. A radio direction .iinding system having a predetermined directivity continuously variable in azimuth, comprising a plurality of antennas in a circular array, a receiver, coupling means connected between said antennas and said receiver, said coupling means comprising a like plurality of phase changers and a plurality of transmission lines, each antenna being coupled to said receiver through one of said phase changers and through said transmission lines, each of said phase changers being controllably adapted to deliver voltages of a selected magnitude and phase, and a control device connected to said phase changers applying a varying control to said phase changers so that said phase changers deliver voltages of varying magnitude and phase to said receiver.

8. A radio direction finding system having a predetermined directivity continuously variable in azimuth comprising a first plurality of aperi-I odic antennas arranged in circular array, a second plurality of aperiodic antennas arranged in a circular array concentric with said rst named array, the separation of adjacent antennas in said first array being substantially one-half wavelength, the radial distance between the two arrays being substantially one-quarter wavelength, a receiver, coupling means comprising a separate phase changer and a transmission line coupling each antenna of both arrays to said receiver, a phase change control device connected to each phase changer whereby in accordance with predetermined voltage characteristics of said control device the phase changers deliver waves of predetermined magnitude and phase to said receiver in accordance with said directivity and means connected to the output of said receiver for indicating said directivity.

9. A radio direction finding system in accordance with claim 8 wherein said phase control device delivers a control voltage to less than half of the number of phase changers included in said coupling means at any instant of time. 10. A radio direction finding system in accord ance with claim 8 wherein each of said phase changers comprises a plurality of vacuum tube ampliers the outputs of said ampliers being connected to a single transmission line and connection means from said output circuits to said line whereby the output of each of said phase changers is the vector sum of the voltage outputs of said amplifiers.

11. A radio receiving system comprising a plurality of aperiodic antennas in linear array, a plurality of receivers, a first coupling means comprising a plurality Aof phase changers, a separate phase changer coupling each of said antennas to one of said receivers, a second coupling means comprising a second plurality of phase changers, a separate phase changer of said second plurality of phase changers coupling each of said antennas to another of said receivers, each phase changer comprising a plurality of vacuum tube amplifiers, each amplifier comprising an input and an outm put circuit, the phase relation between the voltm ages of the input and the output circuits of one amplier being diierent than the phase relation between the voltages of the input and outputs of another ampliiier.

12. A radio receiving system in accordance with claim 11 wherein the phase relations between the voltages of the input and output circuits of all amplifiers included in said first coupling means `are such that the antenna array has a directivity in a first direction and wherein the phase rela-- tions between the voltages of the input and output circuits of all amplifiers included in said second coupling means are such that the antenna array has a directivity in a second direction.

13. A radio direction finding system having a predetermined directlvity continuously variable in azimuth comprising a first plurality of aperiodic antennas arranged in circular array, a like plurality of aperiodic antennas, arranged in a second circular array concentric with said iirst named array, a plurality of phase changers, one phase changer being connected to each antenna of each of said arrays, phase control means connected to said phase changers cyclically conditioning each phase changer to generate from voltage applied thereto by the antenna to which it is connected an output voltage having a predetermined variable amplitude and variable phase, connecting means to combine the output voltages from said phase changers, a receiver, means for connecting said combined voltages to said receiver, and an indicator connected to said receiver for indicating said directivity.

lefIn the method of determining the directivity of a radio transmission from energy received by a plurality of antennasl arranged in outer and inner circular arrays and in which the output from each of said antennas controls the `of all phase changers associated with the antennas of said outer array to produce'a plurality of voltages varying in a predetermined magnitude and phase, simultaneously cyclically varying the biases on the grids of the amplifiers of all phase changers associated with the antennas of said inner array to produce a second plurality of voltages varying in a predetermined magnitude and phase, combining all produced voltages, and determining said directivlty from said combined voltages.

15. The method of determining the directivity of a radio transmission from energy received by a plurality of antennas arranged in outer and inner concentric circular arrays comprising cyclically conditioning overlapping groups of milacent antennas in said outer array to generate a plurality of voltages varying in magnitude and phase, simultaneously cyclically conditioning overlapping groups of adjacent antennas in said inner array to generate s. second plurality of voltages varying in magnitude and phase, generating said plurallties of voltages in accordance with said received. energy and said conditioning, combining all generated voltages, and indicating the directivity ci said transmission from said combined voltages.

16. [i radio receiving system having a variable directivity comprising a plurality of antennas arranged in a predetermined array, a receiver, coupling means connected between said antennas and said receiver, said coupling means comprising plurality of phase changers and a plurality of transmission lines, each antenna being coupled to said receiver through one of said phase changers and through said transmission lines, each of said phase changers adapted to deliver voltages of a selectable magnitude and phase in accordance with the magnitude of the control voltages supplied to said phase changers and a 17 control device for supplying variable voltages to said phase changers, said control device being connected to said phase changers so that said phase changers deliver voltages of varying magnitude and phase to said receiver.

17. In the method of controlling the directivity of reception of radio transmisison from a plurality of antennas arranged in an array, the steps comprising generating voltages of predetermined magnitude and phase, conditioning the energy received from each of said antennas in accordance with said voltages, and cyclically varying said voltages both in magnitude and phase over a range corresponding to the directivity range.

18. In a method of controlling the directivity of reception of radio transmission from a plurality of antennas arranged in an array, the steps comprising generating voltages of different magnitude and phase, conditioning the energy received from each of said antennas in accordance with a separate one of said voltages, and cyclically varying said voltages both in magnitude and phase over a range corresponding to the directivity range.

19. In a method oi controlling the directivity of reception of radio transmission from a plurality of antennas arranged in an array, the steps comprising generating voltages of diierent magnitude and phase. conditioning the energy received from each of said antennas in accordance with a separate one of said voltages, and cyclically and simultaneously varying said voltages both in magnitude and phase.

20. In a method of controlling the directivity ci reception of radio transmission from a plurality of antennas arranged in an array, the steps comprising generating voltages of different magnitude and phase, conditioning the energy received from each of said antennas in accordance with a separate one of said voltages, and simultaneously and continuously varying said voltages both in magnitude and phase.

HENRI G. BUSIGNIES.

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

UNITED STATES PATENTS Number Name Date 1,667,792 Martin May l, 1928 1,738,522 Campbell Dec. 10, 1929 1,922,115 Stone Aug. 15, 1933 1,954,898 Stone Apr. 17, 1934 2,041,600 Friis May 19, 1936 2,140,130 Earp Dec. 13, 1938 2,245,660 Feldman et al June 17, 1941