GB1411779A - Microwave antenna with radome - Google Patents

Abstract

1411779 Aerials R J GRENZEBACK 29 Dec 1972 [12 Jan 1972] 60208/72 Heading H4A A microwave aerial has, in combination, a reflector having a parabolic inner electrically conductive surface, a microwave feed in position to radiate energy to and from the focus of said surface, and a radome having a parabolic inner electrically non-conductive surface. The reflector and the radome are connected together such that their said inner surfaces are confocal. As described, an aerial 12 comprises a feed-horn 46 and four 90 degree reflectorradome segments, of which two, referenced 18, 20, are visible in Fig. 2. Said segments have integrally formed peripheral flanges 32 by means of which they are bolted together, to provide an enclosure having a reflector portion 22 at one end with a parabolic shape reflecting surface 28 and a radome portion 26 at the other end with a parabolic shape interior surface 30. The foci of the surfaces 28, 30 are coincident at a point P, which is also the phase centre of the horn 46. The portions 22, 26 are spaced apart by a cylindrical shroud portion 24 having an interior surface 52, which is corrugated or otherwise made irregular. The segments may be made of fibreglass, and the surfaces 28, 52 of the reflector and shroud portions rendered conductive by metal spraying, or by adhering metal foil or mesh thereupon. The construction ensures that any part of energy from the horn 46 which has been collimated by the reflecting surface 28 and is then reflected back off the interior surface 30 of the radome, passes through the common focus P so that it may be re-collimated by the surface 28. The shroud portion 24 reduces diffraction effects around the edge of the reflector portion 22, and may be omitted if desired. The segments 18, 20, &c. may be nested for transport (Fig. 3, not shown). The construction is also applicable to other forms of parabolic reflector aerials, e.g. a parabolic trough reflector aerial. Specification 1,411,780 was divided from this.