Abstract: An antenna feed comprises, aligned and centered on an axis OO?, a waveguide having an inside diameter, a first end and a second end, a dielectric body having a portion inside the waveguide and a portion outside the waveguide, the outside portion comprising a section of frustoconical shape having an outside lateral surface of frustoconical shape with two ends, namely a large diameter end and a small diameter end, and a subreflector at the large diameter end of the frustoconical shape. The outside portion comprises, in addition to the frustoconical portion, a cylindrical portion whose diameter is greater than the inside diameter of the waveguide. The cylindrical portion is connected to the frustoconical portion at its small diameter end and the frustoconical outside lateral surface of the dielectric body is smooth.

Abstract: An antenna feed comprises, aligned and centered on an axis OO?, a waveguide having an inside diameter, a first end and a second end, a dielectric body having a portion inside the waveguide and a portion outside the waveguide, the outside portion comprising a section of frustoconical shape having an outside lateral surface of frustoconical shape with two ends, namely a large diameter end and a small diameter end, and a subreflector at the large diameter end of the frustoconical shape. The outside portion comprises, in addition to the frustoconical portion, a cylindrical portion whose diameter is greater than the inside diameter of the waveguide. The cylindrical portion is connected to the frustoconical portion at its small diameter end and the frustoconical outside lateral surface of the dielectric body is smooth.

Abstract: The invention concerns the secondary reflectors of SHF antennae of the Cassegrain type. It consists of providing the secondary basic reflector (103) of this antenna with a first circular ring (104) in the shape of a cylinder directed toward the main reflector, and a second ring (105) in the shape of a circular crown fixed to the end of the cylinder, and projecting outward from the latter. These rings are made from a conducting material. The length of the cylinder and the width of the crown are of the range of one quarter of the average wavelength for which the antenna is dimensioned. This enables the “overspill radiation” of the secondary reflector to be reduced considerably, and therefore allows the dimensions of the antenna to be reduced significantly for equivalent performance.

Abstract: The invention concerns the secondary reflectors of SHF antennae of the Cassegrain type.