US 3806930 A
Method and apparatus for controlling the directional pattern of a phased array antenna in one, two or three dimensions and in which the phased array antenna comprises a plurality of individual radiators each of which has a phase shifter that may be adjusted by special resistance values fed by a controlling direct voltage. Phase controlling resistors are arranged analogous to the spacings of the radiators of the antenna array and to form voltage dividers such that the directional characteristic of the antenna array may be adjusted by selectively connecting resistors to the phase shifting network. Means are also provided for tracking a signal as, for example, a satellite and to eliminate jamming signals.
Description (OCR text may contain errors)
United States Patent 1111 3,806,930
Gobert Apr. 23, 1974  METHOD AND APPARATUS FOR 3,484,784 12/1969 McLeod 343/100 SA ELECTRONICALLY CONTROLLING THE FOREIGN PATENTS OR APPLICATIONS PATTERN OF A PHASED ARRAY ANTENNA 1,329,686 5/1963 France  Inventor: Jean Francois Gobert, Munich,
Germany Primary ExaminerMaynard R. Wilbur z m n esens ha B Assistant Examiner-S, C. Buczinski  Asslgnee l g e l Attorney, Agent, or Firm-H1ll, Sherman, Meroni,
Gross & Simpson  Filed: Dec. 14, 1970  Appl. No.: 97,654  ABSTRACT Method and apparatus for controlling the directional 30 Foreign Application priority Data pattern of a phased array antenna in one, two or three dimensions and in which the phased array antenna comprises a plurality of individual radiators each of which has a phase shifter that may be adjusted by special resistance values fed by a controlling direct volt age. Phase controlling resistors are arranged analogous to the spacings of the radiators of the antenna array and to form voltage dividers such that the directional characteristic of the antenna array may be ad- Dec. 23, 1969 Germany l964520 Dec. 23, 1969 Germany 1964521  US. Cl. 343/100 SA, 343/100 TD, 343/854  Int. Cl. H04b 7/00  Field of Search 343/100 SA, 100 TD, 854
 References Cited justed by selectively connecting resistors to the phase UNITED STATES PATENTS shifting network. Means are also provided for tracking 3,145,383 8/1964 Nelson et al 343/l00 SA a signal as for example, a satellite and to eliminate 3,238,528 3/1966 Hines 343/100 SA jamming signals 3,588,901 6/1971 Buck 343/854 3,345,631 10/1967 Chamberlin 343/100 SA 23 Claims, 24 Drawing Figures Y Y Y em. 'lZb 'DECO D/N6 a \PIIASE 0/50. Weiss/102p aw/5f 0/50.
METHOD AND APPARATUS FOR ELECTRONICALLY CONTROLLING THE PATTERN OF A PHASE!) ARRAY ANTENNA BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to an analog phase control system for controlling a directional beam of a one-, two-, or a three-dimensional antenna comprising a plurality of individual radiators each of which have a phase shifter for altering the phase of the signal beam received or radiated by the individual radiator and in which the phase is changed proportionally to a controlling direct voltage feeding resistors which are associated to the individual radiators.
2. Description of the Prior Art Phased array antennas are known which are constructed of individual radiators mounted relative to each other in parallel rows and vertical columns. Each of the individual radiators must be properly phased to obtain the desired directivity and gain of the antenna array.
SUMMARY OF THE INVENTION The present invention provides for correct in-phase control of phased array antenna structures formed with a plurality of radiating elements arranged in rows and columns that are spaced half wavelengths apart and which have phase shifters which are homogeneous. Two linear resistance chains fed by controlling direct current sources such that a first direct current source applies voltage to the first row of resistors in the x direction and a second direct current voltage applies voltage to the column resistors in the y-direction, and in which the resistors are selected so that taps between adjacent resistors in columns and rows vary as a function of the position of the particular resistance tap and which when fed to the antenna array provides the proper delay line as the control voltage. By the use of the voltage dividers and due to the fact that the relationship between the control voltage and the group transit time of the delay lines approaches linearity, a radiation pattern from the array is obtained which has optimal focusing independently of the two control voltages. The magnitude of the xand y-control voltages determines only the direction of the beam focusing relative to the plane of the array.
The invention provides means for creating a simple and accurate phase control for phase shifters of the individual radiators of an antenna array such that the desired phase displacement is proportional to the controlling direct voltages. Thus, a group of radiators mounted in rows and columns but which do not necessarily lie in planes at right angles to each other may be fed. Also, the invention calls for accurate and precise control of the beam of an antenna array which is linearly arranged and by which the individual radiator elements are connected to linear-arranged series resistances which are formed in a mirror image of the antenna array with the direct voltage source connected to the linear series resistance system and the bias voltage for the phase shifters of the individual radiators is removed from the connection points between the individual resistors. With an antenna array lying in a single plane the control of its phase may be obtained with two linear series resistor arrangements, each of which are provided with a direct voltage and with the connection points between the rows and terminals forming a network. The bias voltage for the phase shifters of the individual radiators is taken from junction points between the various resistors. For 5 example, with a flat planar array, a phase control is provided comprising two linear series resistance arrangements each connected to a direct voltage source and with the resistors formed into rows and columns so as to form a network and the junction points of the network provide bias voltages for the phase shifters of the individual radiators corresponding to the position of the resistors. For a three-dimensional radiator arrangement there are provided three linear rows of resistors forming a three-dimensional network with each of the three series of resistors being connected to a direct current source and the bias voltage for the phase shifters of the individual radiators is taken from the corresponding position from the resistive network. The individual values of the resistors is selected so that the resistance is proportional to the distances between the individual radiators.
Thus, one, two or three linear resistive networks with one complementary terminal is capable of providing the phase control for an array for a linear, planar, or three-dimensional radiator. Thus, the resistor layout is extremely simple. The input impedance is very high. Phase control of antenna arrays with radiator elements lying in curves may also be controlled by utilizing inhomogeneous arrangement of series resistors. The proper phase displacement may be accomplished at thehigh frequency or the intermediate frequency portion of the spectrum and frequency multiplication may be used if desired.
Another object of the invention comprises providing a phased array antenna with a sharply focused beam with a tracking system for moving the beam. Tracking systems utilize radiator elements arranged in rows and columns parallel to each other, each having delay devices that may be controlled by control voltages. Such arrays provide narrow fan-shaped directional beams and signals obtained from such antenna arrays allow accurate tracking of signal sources. 1
The present invention provides for automatic tracking by connecting even-numbered and odd-numbered rows and columns of radiators together in which signals being received are fed to a phase discriminator which controls the delayof individual rows and columns of the antenna array so as to track the received signal.
Such phase controlled antenna systems like all other antenna systems are subject to interference from extraneous transmitters which are capable of influencing the tracking system and cause it to track an undesired signal.
The present invention provides for phase control antenna arrays which have fan-shaped directional characteristics which are provided with a discriminator circuit such that when an interfering signal occurs in the range of one of the fan-shaped directional beams, the apparatus for generating a follow-up signal is disabled such that the beam will not track the undesired signal and thus position the beam incorrectly.
Thus, the angular position of the directional beam can be established and maintained with great accuracy without being influenced by undesired interfering signals originating from transmitters or elsewhere.
The invention allows operation of high accuracy and maintains the beam aligned with the target being tracked. The target might, for example, be a satellite or other body.
Other objects, features and advantages of the invention will become apparent from the following description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 comprises a general representation of a threedimensional radiator antenna upon which the signal from a source impinges;
FIG. 2 illustrates the three-dimensional resistances and connections of the invention;
FIG. 3 is a schematic view of a linear resistance element of the invention;
FIG. 4a illustrates a planar antenna array with rows and columns disposed obliquely relative to each other;
FIG. 4b shows the corresponding linear resistance arrangements with connecting terminals for the planar antenna structure of FIG. 4a;
FIG. 5a and FIG. 5 b illustrate respectively different arrangements for controlling the phase of the planar antenna array;
FIG. 6 illustrates the feed arrangement for radiator elements along arbitrary curves and the associated resistance arrangement;
FIG. 7a illustrates antennas arranged in parallel rows;
FIG. 7b illustrates antennas arranged in offset rows;
FIG. 7c is a plot of the phase angle as a function of the scanning angle;
FIG. 8a illustrates an antenna arrangement comprising rows and columns of antennas;
FIG. 8b is a block diagram for controlling the antenna of FIG. 8a according to the invention;
FIG. 80 is a perspective view of the radiation pattern of two antenna arrays according to FIG. 8a which cross each other at right angles;
FIG. 9a illustrates a modified arrangement of an antenna comprising rows and columns;
FIG. 9b is an example of the invention connected to an antenna according to FIG. 9a;
FIG. 10a illustrates the structure of an antenna system for generating three fan-shaped directional patterns;
FIG. 10b is an end view of the antenna beam produced by the antenna of FIG. 10a;
FIG. 1] is a block diagram of the apparatus for controlling the antenna of FIG. 10a;
FIG. 12 illustrates a modified antenna system;
FIGS. 13a, 13b and 13c, illustrate examples of antenna systems utilizing various types of monopulse antennas; and
FIG. 14 illustrates a hexagonal antenna with a triangular grid.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for illustrating the principles of the present invention. A three-dimensional radiator group is designated generally as G and is mounted relative to the x, y and z axes as shown. Radiation is received from a source which has the spherical coordinates determined by the angles (b and 11 which correspond to the azimuth and elevation angle. A represents a particular radiator element but it is to be realized that the radiator group G comprises a number of radiator elements such as A and the present invention provides the proper phase relationship among the various elements by providing a mirror image of the radiator elements from a plurality of impedances to which voltages are applied such that a phase controlling impedance is connected to the antenna element which corresponds to the position of the elements and the impedances. The radiator array should be fed in-phase in the direction (to and v The phase 9 represents the phase of the signal received from a radiator element A.
6,, k' (cosvcosv k' x (sinv' cossinv 005%) k y,
in which k 2 ar/Aand x,,, y,. and z, signify the coordinates of the radiator element A in the Cartesian system as shown in FIG. 1. The phase control angle 6 of the radiator element is defined by the equation The phase angle 9 is thus a linear function of the radiator element coordinates x,,, y, and as illustrated in FIG. 1.
FIG. 2 illustrates a three-dimensional resistance and terminal arrangement which is fed by three independent direct current voltages, V V and V for producing phase control impedances for the various antenna elements of the array G. The resistors R R R and R are connected in series between ground and the voltage V along the x axis and the resistors R R R R and R are connected in series between ground and the voltage V in the y axis. Resistors R R and R are connected in series between ground and the voltage source V in the z axis. The values of the resistors in the x, y and z axes are chosen to be proportional to the distances between the various elements of the antenna G along the x, y and z axes for which the impedance network of FIG. 2 is being constructed.
For example, for the antenna element A illustrated in FIG. 1, there corresponds in the impedance network of FIG. 2 an intersection point a of the three terminal rows which have the potentials V V and V The sum of these three voltages is V =V +V +V which exists at the intersection point and is proportional to the phase angle 0. Thus, there corresponds to greater phase displacements greater voltage values. The resistance and connection of the row arrangements according to FIG. 2 for phase control purposes comprises a mirror image of the radiator arrangement illustrated in FIG. 1 and thus a particular radiator in the antenna array G may be properly controlled and phased by connecting it to the corresponding impedance value from the resistance network of FIG. 2.
It has been discovered that this principle also holds for irregular forms of antenna arrays as well as for those of rectangular or cubical shapes.
FIG. 3 illustrates an impedance network for controlling the phase of a linear phased array antenna. A bias voltage V is connected to the series arrangement of the resistors R R R and R,, which have their other side connected to ground. Phase shifter P for the particular radiator receives at terminal 1 in the voltage V between the resistors R and R which correspond to the position of the radiator in the array. Phase shifter P adds a voltage proportional to the phase angle a which depends on the angular position of the radiator source and the voltage V which appears between the resistors R and R to produce at its output a signal proportional to a +f (V The phase angle alpha dempends on the respective direction of the linear or plane array antenna to the radiation source from which the signal is received. For different angular positions of the radiation source relative to the phase array arrangement different voltage values are developed by the phase shifters for controlling the direction of the antenna.
The principle is also applicable to non-rectangular arrays and for example FIG. 4a illustrates a planar antenna array in which the xs represent radiating elements that are mounted on the rows and columns identified by the letters A-D and A-J, as shown.
As illustrated in FIG. 4b resistors R R and R are connected between ground and a voltage V,, and resistors R R R R and R, are connected in series between ground and a voltage source V Conductors are connected to the junction points between the various resistors for applying phase control voltages to the individual radiating elements of the array. As in the example of FIG. 2, the values of the resistors are proportional to the distances between the radiating elements in the actual planar array of FIG. 4a. A linear relationship exists between the required phase control of the radiators illustrated in FIG. 4a and voltage currentrelationship in the resistance arrangement of FIG. 4b. With reference to equation 2, z, is equal to zero. x and y are proportional to the correspondingresistance values and cos,,- sinv as well as sin,,- sinv, are proportional to the voltages V and V FIGS. 5a and 5b illustrate two different structures for controlling the phase of a planar radiator array. In each system, resistors are connected in series and voltages V and V respectively, are connected to the linear resistors and the other ends are connected to ground with the values of the resistors corresponding to the positions of each radiating element of the array. In FIG. 5a the phase shifter P receives a first voltage from terminal D between the resistors R and R,, corresponding to the position of the particular radiator to which the phase shifter is connected along the y axis, and a second voltage from terminal E between the resistors R, and R corresponding to the position of the particular radiating element along the x axis. The voltages at' terminals D and E provide the proper bias voltage in the phase shifter P to provide the proper phase shift for the particular radiating element of the antenna array.
FIG. 5b illustrates a modification of the invention of FIG. 54 wherein the voltages occurring at terminals D and E are combined in an adder S before being applied to the phase shifter P.
FIG. 6 illustrates a planar attenna array with two linear resistor arrangements superimposed for feeding the radiator array. The antennas are represented by the crosses and a voltage J l feeds the series arrangements of the resistors r -r which are connected between ground and the voltage source J, and a voltage source J feeds the series arrangements of the resistors r,- R connected between ground and the voltage source. The radiators of the array lie on the curves shown in heavy solid line but the magnitude of the individual phase control resistances needed for the antennas is proportional to the spacing in the direction of the rows or in the direction of the columns as illustrated. Thus, the position of the radiator elements may be considered as lying on the curves illustrated in heavy lines but they may be properly fed to obtain the proper phase relationship by controlling their phase control with the linearly arranged resistors, as shown.
The principles of this invention are also applicable to control three-dimensional radiator arrays with three linear resistance systems as illustrated in FIGS. 1 and 2. Such three linear resistance systems may be suitably used for radiator elements which lie on curved surfaces such as surfaces of spheres, cylinders or cones, through an extension of the principle illustrated in FIG. 6 and by using three linear resistance rows. The voltages associated with each of the radiating elements as illustrated in FIG. 2 are added and supplied as the bias voltage to the phase shifter for the particular element and the other terminal of the particular phase shifter is connected to ground.
The phase shifters and phase control devices may be used for feeding radiator systems of the prior art by utilizing principles of this invention. For example, the invention may be used with radiators which have variable spacing as, for example, those with hexagonal symmetry. The feed for the phase control may be nonhomogeneous which gives rise to further applications of the invention.
Generally, the phase shifters used will have a very high input impedance and will have a linear relationship between the bias voltage and the phase angle independently of the magnitude of the signal over the broadest possible range, as well as having a continuous phase displacement. The phase displacement range should be as great as possible. Spiral ferrite delay lines may be used as phase shifters, for example, and which have very desirable performance characteristics.
FIG. 7a illustrates radiator elements shown by crosses arranged in the rows Al and A2. The rows are parallel to each other and the radiator elements are aligned as shown and are fed in like phase. When the signal components of all the radiator elements are added, the signals from the radiator row Al and the radiator row A2 remain equal. The phase difference between the radiator elements such as for example, a1 and a2 is represented by the angle B. Since several radiator elements are connected in parallel, the output voltage will be higher and a measurement may more easily be obtained. FIG. 7b illustrates radiator elements arranged along line Al or A2 but with the individual elements offset from each other but with the same spacing of the radiator elements made in both rows. Between the radiator elements 0'1 and a'Z there exists a phase difference of B. The phase measurement depends on the coupling between the elements a'l and 0'2 but not on the coupling between the elements a'l and a'3 (or the elements in a particular row). If the rows of the radiator elements A'l and A2 lie far apart, the coupling between them is very weak and the rise of the phase angle B as illustrated in FIG. is very great as a function of the scanning angle v. FIG. 70 illustrates a family of curves identified by the spacings at the ends of the curves in the upper right-hand corner for the distance between the rows A1 and A2, and Al and A2, respectively, in FIGS. 7a and 7b. A range B on both sides of the value v gives the preferred direction of the directional beam. If both of the radiator rows lie far apart the coupling influence is weak and the associated curve of FIG. 70 climbs very steeply. However, with this arrangement there is a drawback that the phase reading is no longer unambiguous unless it is maintained in the range about the value of v 0 as for example B. In each particular case a compromise must be made between the disadvantage of the coupling and of the resolution on the other hand which depends on the properties to be achieved with the particular apparatus. A radiator group for example of two rows should be driven in correct phase with respect to a given active or passive remote radiation source when the measured phase difference between the rows A1 and A2, and A'l and A2, respectively, equals zero. This criterion, however, no longer holds if a second radiation source is present as, for example, in the form of an interfering transmitter. In this case both sources would be detected by the beam which is generated by a pair of radiators mounted in rows.
The radiation diagram of two linear arrays spaced apart by an amount of a half wavelength or less does not contain any side lobes. There is a threshold value in actual practice which limits the phase discriminator curve in the zone of the main beam. Up to a certain amount greater spacings between the twin rows of antenna elements may be chosen without rendering the measurements ambiguous.
FIG. 8a illustrates an antenna array which includes two pairs of rows of antenna elements which cross each other at right angles and are of the form of that illustrated in FIG. 7a. The first pair of radiator elements is designated A1 and A2 and the second pair is designated A3 and A4. Such structures generate fan-shaped radiator patterns S1, 2 and S3, 4, respectively, as illustrated in perspective in FIG. 8c. In FIG. 80, for simplicity, only a single row of radiator elements is illustrated for each pair of radiator element rows.
FIG. 8b illustrates the radiator array as well as the ap paratus for controlling the phase displacement by the numeral 10. The radiator elements of the array including the rows Al and A2 are designated 11 and the radiator elements comprising the rows A3 and A4 are designated 12. The associated phase shifters are designated 11a and 12a. Although these are illustrated in FIG. 8b as being physically separated from the pairs of antenna rows 11 and 12, it is to be realized that they may actually be integrally formed with the radiator rows. The output from the antenna rows 11 and 12 are respectively connected to phase discriminators 11b and 12b. A low frequency generator 13 produces control signals which are delivered to the phase shifters 11a and 12a through switches 14 and 15. By changing the phase of the antenna elements the fan-shaped electrical beams S1, 2 and S3, 4 may be moved. The sharply focused directional beam SP occurring at the intersection of the fan-shaped beams S1, 2 and S3, 4 may also be controlled by varying the phase shift of the elements of the antenna. The generator 13 then allows searching to occur with the beams of the antenna. As soon as an active or passive target has been located, the switches 14 and 15 are moved out of engagement with the output of the generator 13 and into engagement with contacts connected to the outputs of phase discriminators 11b and 12b so as to track the particular target. The antenna arrangement 10 also supplies an output to a threshold evaluator 16 which feeds a receiver 17. The device 16 may also include decoding arrangements for identifying answering relay stations.
In FIG. 9a there are shown four pairs of rows of radiator elements designated as Al-A8 which cross at right angles. The first two pair of radiator elements comprise the rows A1 and A2; the second two rows comprise the elements A3 and A4. The elements A2 and A3 may be the same physical elements in that the elements may form one of the pair of rows with the row A1 and the second pair with the row A4. The spacing between the rows is M2 so as to eliminate interference caused by side lobes. The horizontal rows of radiator elements are designated as A8 and A7 which form the first row and A5 and A6 which form the second row. The rows A6 and A7 may be the same elements as are the rows A2 and A3. The phase angles between the individual rows are preferably kept within the range of i 45 so as to obtain maximum sensitivity control. The corresponding fan-shaped radiation patterns I and II are illustrated adjacent the pairs of rows of radiator elements. It should be noted that the overlapping zone in the middle of the fan-shaped radiation characteristic is shaded and corresponds to the zone designated as SP in FIG. 80. If an interfering transmitter TJ lies in the range of the fanshaped radiator I, it is picked up by one row of the radiator elements but not by the other row if it does not lie in the shaded portion of the radiation characteristic. This allows the interfering transmitter to be eliminated by suitable means.
Means for accomplishing this is illustrated in FIG. 9b which shows a receiving device similar to that illustrated in FIG. 8b and corresponding reference symbols are utilized for corresponding parts. The individual rows of antenna elements Al-A8 are shown. A switch H allows the output of the rows of antennas A1-A4 on one hand, and A5A8 on the other hand to be selected. In the event that a target and an interference source exists in one of the two fan beams, which have been controlled by the low frequency generator 13 so as to locate the target by scanning, the threshold value of evaluator 16 is not reached because that particular fanshaped beam will be aligned at about mid-point between the target and interference source, and searching will be again carried out. The treshold vaue of evaluator may be a Schmitt circuit as described in the book entitled Pulse and Digital Circuits" by Millman and Taub, 1956, McGraw-Hill Book Company, pages 164-172. Such circuits operate as threshold evaluators and produce an output voltage only when an input voltage exceeding a predetermined value is applied. If such minimum input voltage is not received there will be no output from the circuit. After the new search operation, when the target is located, the other fan-shaped beam will be switched on and it will be focused with its maximum on the target since no interference source is present in that particular fan beam. As illustrated in FIG. 8c the two fan-shaped beams intersect at right angles to each other and in the case of a radiator arrangement according to FIG. 9a the two fan-shaped beams can be independently moved to cover a large area due to the large number of radiator elements. If one of the fan-shaped beams covers an interfering source as well as the desired target the sum of the signals from the desired target and the interfering source causes the pointing angle of the antenna to be directed to a point between the two sources. Thus this antenna searches for a fictitious aim between the actual radiation source and the interfering source. However, because of the interference effect the received voltage is not sufficiently large to actuate the threshold value of evaluator l6 and the system will switch to the other fan-shaped beam which is at right angles to the first one. The second fanshaped beam will pick up only the actual desired radiating source and will be free from the interference source due to the fan-shape of the beam. It is to be realized of course that the interfering source cannot lie in the plane of both of the right angle beams unless it is directly aligned with the desired radiating source. Thus the use of the two beams allows the antenna arrays to be correctly adjusted to the desired radiating source by switching between the two.
Thus, the structure of FIG. 9b allows various pairs of rows of antenna elements to be selected such that suitable pairs are selected in which the interference signal does not cause errors in the tracking of the desired radiation source.
FIG. 10a illustrates three pairs of radiator element rows with each pair designated respectively by the numerals 22, 23 and 24. The first pair of radiating elements is enclosed in solid line and designated 22; the second pair of antenna elements is designated by numeral 23 and is enclosed by dashed lines; and, the third pair of antenna elements is designated by numeral 24 and is enclosed by dot-dash lines. Each of the pairs of radiator elements produce fan-shaped characteristics as illustrated in FIG. 10b and the three fan-shaped patterns intersect at the center to form a sharply focused beam SP within which the desired target is located. An interfering transmitter TJ that lies in the zone of one of the fan-shaped directional characteristics as, for example, that of the pair of antennas designated by the numeral 23, can be eliminated because the signals from this group of antennas (23) will not be utilized for directing the actual directional beam SP. The antenna arrangement illustrated in FIG. 10a has the advantage that if one of the fan-shaped directional beams intercepts an interfering signal, the other two still allow clear pickup and tracking with the antenna system on targets.
FIG. 11 is a block diagram of the equipment utilized with the antenna system according to FIG. 10a. Elements common to those illustrated in FIGS. 8b and 9b are designated by the same numerals. The circuit is very similar to that illustrated in FIG. 9b but includes a switch 21 for switching out any one of the three pair of antenna elements, 22, 23 and 24, when an interfering signal occurs.
Another application of the invention is illustrated in FIG. 12 in which a hexagonal array 46 is shown. It is to be noted that elements are mounted on first horizontal lines designated 47a-47i; the second lines slanting generally up toward the right relative to FIG. 12 and designated 4811-481; and, the third group of lines designated as 4911-491, slanting generally up toward the left edge of FIG. 12. The antenna elements are mounted at the intersection of the group oflines 47, 48 and 49. The antenna elements may be spaced half wavelengths apart as illustrated. The radiation pattern is improved if the energy applied to the individual radiators decreases as a step function of distance to the center of the array. Greater distances may be maintained between the individual radiators to vary the accuracy of the phase control and when the coupling effect of the antenna is to be changed.
The phase control is used mainly for reception purposes. The linear twin arrays may be part of a planar array system however their phase shifters have to be regulated. The phase control system may also be located adjacent the installation of the main antenna so that an optimum design may be obtained with regard to radiator spacing and feeding. There is an advantage of such an arrangement in that an antenna according to the present invention is very mobile.
FIGS. l3a-l3b illustrate how improved antenna gain may be obtained from twin arrays. The phase discriminator 30 in FIG. 13a allows the phase difference between the signals in the two identical array halves 31 and 32 to be nullified. The array system may also be split in a perpendicular direction into two halves 33 and 34 as shown in FIG. 13b so that the discriminator 35 can obtain phase control in the other direction. No ambiguities result if the threshold value is chosen high enough or if the spacing of the twin array radiator center is less than a fixed value. FIG. 13c illustrates the entire phased array antenna.
FIG. 14 illustrates a triangular grid array with hexagonal formation. Phase discriminators 36, 37 and 38 allow the phase differences between the various portions of the array to be eliminated. The entire antenna array is designated by numeral 51 and each of the triangular partial sections of the array are designated by the numerals 52-57. 7
It is seen that this invention allows the phase relationship of an antenna array to be controlled by synthesizing impedances which vary as a function of distance and which are fed to phase controlling elements respectively connected to the various components of the array to control it.
Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.
1. A two dimensional steerable directional antenna array including a plurality of radiating elements arranged in rows in a plane, a plurality of phase-shift devices, each associated with a radiating element, and the phase shift of which is continuously variable within a predetermined range and proportionally to a controlling d.c. voltage, two rows of series-connected resistors connected together to provide tapping points each of which represents the relevant planar dimensional coordinates of said antenna elements, two regulated d.c. coltage sources respectively connected across said two rows of series-connected resistors, wherein each antenna phase-shift device derives its controlling voltage from those tapping points which represent its spatial co-ordinates; and wherein the resistances of the resistors between the individual phase-shift devices are proportional to the spacing distances between the corresponding individual antenna elements.
2. Apparatus according to claim 1, wherein the greatest resistance value of any one of said series connected resistors is substantially smaller than the input impedance of the phase shifters.
3. Apparatus according to claim 1, wherein the total impedance of the series connected resistors is not small relative to the total impedance of said phase shifters.
4. Apparatus according to claim 1, in which said phase shifters have very high input impedances.
5. Apparatus according to claim 1, wherein said phase shifters have a response which is linear over a broad range between the bias voltage received from said resistors and the phase angle and which is independent of the magnitude of the signal.
6. Apparatus according to claim 1, in which said phase shifters comprise spiral ferrite delay lines.
7. Apparatus according to claim 1, in which the spacings of the radiating elements between rows and columns is one-half wavelength or less.
8. Apparatus according to claim 1 in which the feed energy for the individual radiator elements decreases as a funtion of the distance from the center of the array.
9. Apparatus according to claim 1, in which said radiator row pairs form a portion of a planar array system.
10. Apparatus according to claim 1, in which said linear radiator row pairs are mounted adjacent a planar array system.
11. Apparatus according to claim 1, in which four array quadrants are provided and for measurement in one of two directions, two oppositely mounted array quadrants are controlled so that their phase difference relative to each other tends toward zero.
12. Apparatus according to claim 1, in which six triangular array sectors are provided for forming a hexagon, and two non-adjacent array sectors are controlled so that their phase difference relative to each other tends toward zero.
13. Apparatus according to claim 1 in which the spacings of said radiating elements is non-uniform and the values of said two rows of resistors are non-linear and vary as a function of the radiating element spacings.
14. Apparatus according to claim 1 in said planar antenna array, wherein said phase shifters of said individual radiating elements are connected to the junction points of said two rows of said resistors to obtain a phase control voltage which varies as a function of the position of said radiating element in said array.
15. Apparatus according to claim 14, in which said phase shifters have two terminals with one connected to ground, means for adding bias voltages for said phase shifters connected to said two plurality of resistors such that the voltages received are functions of distances of the associated radiating elements along coordinate axes.
16. Antenna arrangement according to claim 14 comprising an electronic beam scanning means of a sharply bundled directional characteristic comprising a control system for obtaining this directional characteristic, consisting of radiating elements arranged in respectively parallel rows and colummns and arranged in a plane and whereby each one of them comprises a delay system which can have its transist time changed by a control voltage, whereby at least individual rows and columns are switched together for the production of narrow, fan-shaped directional characteristics, and control signals for the control of the sharply bundled directional characteristics are obtained in a phase discriminator respectively associated with each receiving direction, for the rows or columns, respectively, from the phase differences of the receiving signals between the individual rows and columns characterized in that a switch-over device is provided in the receiving devices, which are associated with the fan-shaped directional characteristics, and associated with the phase discriminator for switching off a phase beam and for switching on another fan beam, and the switch-over device is controlled by a threshold value device set to a signal level of these two fan beams and will switch to the other fan beam, when the threshold value is not reached during reception with the aid of a fan beam, in such a way that interferring signals received by the transmitter elements of the associated rows or columns during the occurence of interference in the range of one of the fan-shaped directional characteristics will have been rendered uneffective for the production of the subequent adjustment signals of the sharply bundled directional characteristics.
17. Apparatus according to claim 16, in which said receiving means includes a threshold device connected to said discriminator means.
18. Apparatus according to claim 17, including a switching means between said radiator elements and said discriminator means for switching in another fanshaped beam and said switching means controlled by said threshold device.
19. Apparatus according to claim 18, in which said radiator elements are arranged into three pairs of rows for forming three fan-shaped beams and including three corresponding phase measuring means for said three fan-shaped beams.
20. Apparatus according to claim 19, in which said radiator elements are arranged in a hexagonal structure formed from groups of two parallel rows.
21. A three dimensional steerable directional antenna array including a plurality of radiating elements arranged in three rows spatially arranged to form a three dimensional array, a plurality of phase-shift devices each associated with a radiating element and the phase shift of which is continuously variable within a predetermined range and proportionally to a controlling d.c. voltage, three rows of series-connected resistors connected together to provide tapping points each of which represents the relevant spatial co-ordinate of an individual antenna element, three regulated d.c. voltage sources respectively connected across said three rows of series-connected resistors, wherein each antenna phase-shift device derives its controlling voltage from those tapping points which represent its spatial co-ordinates; and wherein the resistances of the resistors between the individual phase-shift devices are proportional to the spacing distances between the corresponding individual antenna elements,
22. Apparatus according to claim 21, wherein said individual radiating elements are mounted in a hexagonal shape.
23. Apparatus according to claim 21 in said threedimensional antenna array, wherein said phase shifters of said individual radiating elements receive three voltages from said first, second and third rows of resistors which vary as the function of the position of said element in said spatial array and second terminals of said phase shifters connected to ground and the second terminals of the three voltage sources connected to ground.