GB603449A - Improvements in or relating to wireless antenna arrangements - Google Patents

Abstract

603,449. Directive radio systems. TAYLOR, D. June 20, 1945, No. 15790. [Class 40 (vii)] A directive receiving or radiating radio aerial, arranged for searching or scanning purposes, comprises means for oscillating the directive beam in a chosen plane over a limited sector, and means for causing the sector to change its angular direction in the same plane at a lower angular velocity, either by sweeping to and fro over a larger sector or by performing a continuous rotary movement. As shown, the system comprises a reflecting mirror 10 which is driven in an oscillatory motion about the horizontal axis 11 by means of the driving mechanism 12, so that the axis of the mirror is swept repeatedly over the angle x-y, and an aerial array 13 which is situated at or near the focus of the mirror: The array 13 is supported by an arm 14 and is driven to and fro between the limits 13a, 13b by means of the driving mechanism 16 so that, with the mirror in the position shown, the directive beam oscillates between the directions a and b. The limited sector a-6 consequently sweeps to and fro with the motion of the mirror, so that the whole sector x<1>-y<1> is repeatedly scanned. The mirror 10 may, alternatively, be made to rotate continuously about the axis 11 and also its angular velocity within the sector x to y may be made to differ from that within the sector y to x. In order to record the instantaneous position of the beam when the arrangement forms part of a radar system, the outputs from the Selsyn devices 17 and 18, controlled by 12 and 16 respectively, are compounded in a further Selsyn device 19, the output from which may operate voltage control means such as a potentiometer, or control the deflector coils associated with a cathode-ray tube display. As an alternative to the mechanical movement of the array 13, the beam oscillation may be obtained by electrical methods such as by varying the phase- or power-relationships between an array of dipoles or wave-guide horns. A form of phase-altering device suitable for use with the wave-guide horns is described in Specification 597,258.