GB612598A - Improvements in wireless aerial systems - Google Patents

Abstract

612,598. Aerials. BOHM, O. M., and WRIGHT, C. S. May 31, 1946, No. 16611. [Class 40 (vii)] A directive aerial system comprises a waveguide-fed mirror reflector and, to effect small adjustments of the directivity of the system, an angularly movable vane situated within the mouth of the wave-guide and rotatable about an axis perpendicular to the direction of wave propagation and to the electric vector of the wave. In a radar system as illustrated, where the exploring wave is radiated from the cheese aerial 1, and the echo signals are received by the cheese aerial 4 wherein the two horns 5 are rendered alternately operative by the switch 7 to provide beam switching, the re-radiation occurring from the blocked to the conducting horn produces a frequency-dependent shift in the directivity of the system. To counteract this effect, vanes mounted on a vertical axis with their planes substantially normal to the wave-guide mouth are situated in both of the horns 5. The vanes, which may be adjusted independently, are normally coupled together through suitable gearing so that simultaneous adjustments may be made in each guide, Fig. 2 (not shown). The spindle which comprises the axis of each vane may be made such that it acts as an impedance matching device to com. pensate for any mismatch occurring at the open mouth of the guide. The invention is also applicable to systems, using a single wave. guide horn, which it is desired to line up with an optical line of sight, as, for example, in gunnery control apparatus.