GB893008A - Frequency sensitive rapid scanning antenna - Google Patents

Abstract

893,008. Aerials. HUGHES AIRCRAFT CO. March 23, 1955, No. 8525/55. Class 40(7). In a radar system with a stationary scanning antenna, rapid scanning with a narrow beam is accomplished by a periodic frequency variation of the antenna supply. The beam source consists of series of slots in a metal plate which lies at the focal line of a parabolic reflector. The slots are energized from a folded waveguide beneath the plate. In order to render the slots resonant over a specific frequency band either recesses are cut at each end or the slots are filled with dielectric. The energy from the slots is directed to the parabolic reflector either by a vane projecting over the slots or by second and third rows of slots on either side of the first row which act as a director and reflector. As shown, slots 42 are energized from the input 13 through the waveguide 12, the energy not radiated being absorbed by a dummy load at 14 to prevent reflections. The folded section of the guide is enclosed in cover member 24 which exposes a row of emitting slots on each side aligned near the focal lines 34, 46 of the reflectors forming the complete reflector 44. The vanes 20 direct the slot emission to the reflectors 44. The emitted beam is deflected about a mean position, in the plane containing the folded waveguide, through an angle which is a function of the slot separation along the waveguide and along the focal line.