Patent GB-1163215-A (GB)
Title: Improvements in or relating to Aerial Arrays
Inventor: ARBON ROBERT STANLEY
IPC: H01Q3/38
Filed: 1967-04-11
Abstract: 1,163,215. Aerials. GENERAL ELECTRIC & ENGLISH ELECTRIC COMPANIES. 10 April, 1968 [11 April, 1967], No. 16476/67. Heading H4A. In an aerial array each signal feed path to a radiating element contains a plurality of selectively operable discrete phase-shifting elements, and apparatus is provided for controlling their settings comprising a register for each radiating element, an accumulator, means for inserting in said accumulator a number representative of the phase shift required in the feed path to a radiating element at one end of the array, means for successively adding to the number in the accumulator each of a series of numbers which are respectively representative of the differences between the phase shifts required in each adjacent pair of feed paths starting at one end of the array and moving progressively to the other end of the array, and means for respectively inserting the numbers successively stored in the accumulator into the registers. As described, an aerial. array comprises sixty-three radiating elements disposed in a straight line. The elements may be in the form of dipoles or resonant slots and each has a separate waveguide feed path, each feed waveguide housing five ferrite phase-shifting elements arranged in tandem, their respective phase shifts being 180, 90, 45, 22¢ and 11“ degrees. A five-stage register 1 is associated with each set of phase-shifting elements, each stage controlling a particular element through a silicon controlled rectifier. Thus a register containing the binary number 01011 indicates a phase shift of (90+22¢+11“ degrees), that is of 123¥ degrees. In this way, phase shifts from 0 to 360 degrees, in 11“ degree steps, may be introduced in any feed waveguide. The five-stage registers 1 are disposed in a cascade arrangement, with a set 2 of five gates intermediate each pair. The input end of the cascade arrangement is connected via a set 4 of five gates to the outputs of the five most significant digit stages of a twelve-bit accumulator 3.  In the above embodiment it is required that the phase-shifting means in the feed waveguides should be set in accordance with the expression a n<SP>2</SP>, where a is a constant and n is the number of a radiating element counting from the centre of the array. Electronic scanning as required, for example, for a radar system may be provided by the insertion of a suitable additional phase difference between each pair of radiating elements at each transmit/receive cycle. The accumulator 3 is initially set at a number representing the phase shift required for the feed waveguide at one end of the array. A twelve-bit increment register 9 is initially set at a number representing the difference between the phase shifts required for the feed waveguide at the end of the array and the next feed waveguide. A seven-bit register 10 is set at a number representing the second differential of the phase shifts in the feed waveguides, which is constant. The circuit arrangements are such that in repeated operations during a cycle the various values of phase shifts required are fed out of the accumulator 3 until each is stored in the appropriate registet I. Operations are initiated by a pre-receive pulse from a computer associated with the radar system. The phase-shifting elements in the feed waveguides are set according to the numbers stored in the registers 1 following a pre-transmit pulse from the computer. In another embodiment the phase-shifting elements in the feed waveguides may be set in accordance with the law a n<SP>x</SP>, where x is a whole number, and in another embodiment the settings are made in accordance with a predetermined random pattern.