US 3482245 A
Description (OCR text may contain errors)
Dem 1969 6. LE PARQUIER 3,482,245
ELECTRONIC SCANNING ANTENNAE Filed Dec. 20. 1966 .12 H I 43 3 so 2J com are I' I a INVIIPTIR' L s, A P-q 1.p.q g
United States Patent 3,482,245 ELECTRONIC SCANNING ANTENNAE Guy Le Parquier, Paris, France, assignor to CSF- Compagnie Generale de Telegraphic Sans Fil, a
corporation of France Filed Dec. 20, 1966, Ser. No. 603,713 Claims priority, applicatsiorkg rance, Dec. 21, 1965,
Int. Cl. (3018 7/44 US. Cl. 343100 3 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to directive antennae of the type comprising a pulurality of radiating elements and wherein the scanning of a given angle by the beam is produced by phase shifting the various radiating elements with respect to each other.
To obtain a given deviation of the radiation direction of the antenna, it is known to phaseshift each radiating element with respect to the others by a value which, instead of being exactly that necessary, is an approximate value selected amongst a plurality of quantization levels. A systematic phase error, due to this quantization, occurs therefore at each radiating element. Assigning the sign to a phase error, if the actually selected phase value is higher than the desired value, and the sign in the opposite case, the directions of the errors for the whole antenna will be symbolized by a succession of and signs which forms a code. This code may be either predetermined or determined by rounding ofl each phase value to the nearest quantized value. The expression representing the resulting diagram of such an antenna used both for transmission and reception is obtained by making the prodnot of the expressions representing the radiation diagrams for the transmission and for the reception. The transmission diagram expression generally consists of the sum of a term representing the antenna transmission diagram without phase error caused by the quantization and of an infinity of terms, due to phase errors, representing an infinity of diagrams elaborated from the diagram without phase error by attenuation (decreasing function of the amplitude of the phase errors) and angular rotations (function of the direction of the phase error at each radiating element). The diagram of the antenna during transmission in a given direction presents therefore a series of maxima and minima as a function of the angular direction.
Up to now, the same phase values for the various radiating elements were maintained during transmission and reception for a given direction of the beam of the antenna.
The expression representing the resulting diagram is therefore equal to the square of the expression representing the transmission diagram and has the same number of minima and of maxima as the transmission diagram (their amplitudes being raised to the square). In order to reduce the importance of the lateral lobes so determined, it is an object of the invention to modify, at the reception of a signal, the code representing the direction of the phase error at the different radiating elements used for the transmission of this signal. This results in a shift of the angular position of the minima and maxima of the antenna diagram during reception, relative to their positions during transmission, for a given direction of the beam.
The resulting diagram of the antenna will have narrower lateral lobes, and the number of minima it presents is generally equal to the sum of the numbers of minima of the transmission and reception diagrams. These lateral lobes will, on the other hand, have a lower mean level, the least favourable case being that in which certain maxima at the transmission and at the reception are coincident. For the lobes corresponding to this least favourable case, one is in the same case as if the code between transmission and reception were not changed.
According to the invention, there is provided an electronic scanning antenna, both for transmission and reception purposes, comprising: an array of a plurality of radiating elements; common power feeding means; a plurality of controlled phase shifting means respectively connected between said radiating elements and said common means for shifting the phase of said radiating elements by quantized amounts and having respective control inputs; computing means for computing the phase of each radiating element for any desired direction of the beam of said antenna and for determining said quantized amounts, said computing means having a plurality of outputs respectively connected to said control inputs, data inputs and a direction-of-the-phase-error input; and controlling means connected to said direction-of-the-phase-error input for indicating to said computing means the direction-of-the-phaseerror in the determination of each of said quantized amounts, according to a code different for transmission and reception in said desired direction of the beam.
More particularly the code used for the reception may be the complement of the code used for the transmisson, i.e. for each radiating element the direction in which the phase error occurs during transmission is reversed during reception. In this particular case, the attenuated and angularly displaced diagrams which enter into the composition of the transmission diagram of the antenna, are again present without angular offset, but with opposite phase, in the reception diagram. From this, it results a substantial reduction of the secondary lobes in the resulting diagram of the antenna.
The invention will be further described, with reference to the accompanying drawing, showing an embodiment of an electronic scanning antenna according to the invention, in which the used reception code is the complement of the transmission code.
The drawing shows an electronic scanning antenna, comprising an array of radiating elements 1', j, located on a surface or along a line, where i is a whole number between 1 and p and j is a whole number between 1 and q. These radiating elements are respectively connected to phase shifters 1, i, j, which can introduce phase shifts, having quantized values between their inputs and outputs. These phase shifters are supplied with ultra-high frequency power from a common main connection 2, through connection 2, i, j, which distribute the ultra-high frequency power between the various radiating elements.
The control of the value of the quantized phase shift introduced by the phase shifter, 1, i, j, is achieved by a phase computer 3 connected to the control input of the phase shifters by connections 3, i, i. The computer 3 has inputs 30, 31, 32, 33, 34. The input 30 and the input 40 of a memory 4 are connected to a terminal 10. The output 41 of the memory 4 is connected to a terminal 52 of a switch 5 which connects it either to its terminal or to its terminal 51. The terminal 50 is connected to terminal 50 of a switch 5 through a multiplier 6, multiplying by 1. The terminal 51 is connected to the terminal 51 of the switch 5' through a multiplier 7, multiplying by 1 (i.e. an inverter). The terminal 52' of the switch 5' is connected to the input 34 of the phase computer 3.
The operation is as follows:
The computer 3 receives at its inputs 31, 32 and 33, respectively, the instantaneous theoretical desired elevation s and bearing g and the value of the operating wavelength A.
The predetermined code, according to which the direction of the phase error for each radiating element during the transmission must be selected, is stored in the memory 4.
The memory 4 and the computer 3 are controlled simultaneously, for example, by means of a program applied to the terminal 10, so that the memory supplies at its output 41 the indication of the error sign in accordance with the code, for each phase shifter, at the instant when the quantized phase shift, which this phase shifter must supply for a given elevation and bearing, is being calculated. During transmission, the synchronous switches 5 and 5' respectively connect, between themselves, the terminals 50 and 52, and 50' and 52'. The signals indicating the direction of the phase error, which are supplied at the output 41 of the memory, art transmitted without modification to the input 34 of the computer which, therefore, receives at the desired instant, the indication of the direction in which it must apply the phase error for a given phaseshifter.
During reception, the synchronous switches 5 and 5 respectively connect between themselves the terminals 51 and 52, and 51' and 52'. The signals indicating the direction of the phase error, which are supplied at the output 41 of the memory, are transmitted to the input 34 of the computer through the multiplying device 7 which multiplies by l, thus reversing the direction of the phase errors to be applied at all phase shifters. Multiplier 6 is used to equalize the paths of the signals between the memory 4 and computer 3.
However, preferably, when the rounding off to the nearest quantization level introduces only a small error (for example, smaller than a quarter of the quantization step), the computer will not change the direction of the error, even if this is indicated by the code. In fact, it is preferable, in this case, not to change the direction of the error, because its absolute value would become much greater (for example, more than three quarters of the quantization step).
Of course, the invention is not limited to the embodiment described which has been given solely by way of example. In particular one may use an antenna for which two different codes have been stored, one of which is used for the transmission and the other for the reception.
What is claimed is:
1. An electronic scanning antenna, both for transmission and reception purposes, comprising: an array of a plurality of radiating elements; common power feeding means; a plurality of controlled phase shifting means respectively connected between said radiating elements and said common means for shifting the phase of said radiating elements by quantized amounts and having respective control inputs; computing means for computing the phase of each radiating element for any desired direction of the beam of said antenna and for determining said quantized amounts, said computing means having a plurality of outputs respectively connected to said control inputs, data inputs and a direction-of-the-phase-error input; and controlling means connected to said direction-ofthe-phase-error input for indicating to said computing means the directionof-the-phase-error in the determination of each of said quantized amounts, according to a code different for transmission and reception in said desired direction of the beam.
2. An electronic scanning antenna as claimed in claim 1, wherein said controlling means comprise: a memory for storing at least one code; and connecting means for connecting said memory to said direction-of-thephase-error input and for changing the code provided by said memory to said computing means according to whether said antenna is used, in said desired direction of the beam, for transmitting or receiving purposes.
3. An electronic scanning antenna as claimed in claim 2, wherein said memory stores only one code and wherein said connecting means comprises an inverter and switching means for connecting said inverter between said memory and said computing means during transmission or reception only.
References Cited UNITED STATES PATENTS 3,387,301 6/1968 Blass et a1 343l00 RODNEY D. BENNETT, JR., Primary Examiner T. H. TUBBESING, Assistant Examiner US. Cl. X.R.