Abstract: A radar reflector comprises a pair of opposed colinear solid dielectric lens reflectors (10) and two corner reflectors (11) between to provide substantially uniform and high reflectivity in the plane of the reflector elements. Radar energy strikes the outer convex surface of a first converging lens element (12) of relatively high dielectric constant and is then transmitted through a second lens element (17) of material having a relatively lower dielectric constant to a reflecting metallic coating (18) on the outer convex surface of the second lens element (17). The surfaces of the two lens elements (13, 14, 18) are formed such that their respective radii of curvature decrease with distance from the axis of symmetry (15). The first lens (12) is preferably silica flour in a polyester resin with a dielectric constant substantially equal to 3.4 while the second lens element (17) is an expanded foam polystyrene with a dielectric constant substantially equal to 2.

Abstract: A lightweight radar reflector comprising two converging lenses (21 and 22) with a reflecting surface (26) applied to the outer convex surface of one of the lenses. The lenses are preferably meniscus lenses provided with peripheral mating flanges (24 and 25) for assembly. In one form the lenses are moulded from a mixture of silica powder and polyester resin to give a dielectric constant of 3.414 for each lens. In one arrangement there may be provided means to allow the lenses to be set to a predetermined separation so that the radar reflectance of the combination can be adjusted. In a further form the lenses may comprise thin shells of polycarbonate filled with silica powder to produce the desired dielectric constant.

Abstract: A passive radar target comprises a sond lens (50) of substantially uniform dielectric constant, having a reflecting surface (51) integrally formed therewith, the lens being constructed of particulate material having a dielectric constant selected such that radar waves striking the surface of the surface of the lens are focussed on the reflecting surface. In one form the particulate material comprise silica flour (91, 101) contained within a thin radar transparent polycarbonate shell. The shell is formed of two similar halves (102, 103) with a pressed aluminum reflective lining (92, 106) in one half. By making the lens axially symmetrical such that the forward and rearward surfaces have a radius of curvature that decreases with distance from the axis of symmetry (102, 103) the lens-reflector can be made to operate over a wide solid angle.

Abstract: A filament winding machine suitable for winding a hollow closed fibre-reinforced body such as a radome comprises a rotateable former 1, an annular spider 3 supporting a plurality of asymmetrically spaced filament guides 19 movable so as to be able to traverse the length of the former to a position beyond the closed end thereof, and an array of circumferentially spaced spigots 26 at or near the closed end of the body to retain laid fibres such that there is no slippage of fibres as they are laid over the closed end of the body.