Multi-beam lens-reflector for satellite communications: Construction issues and ground plane effects

A two-layer hemispherical lens is reported which, combined with a ground plane, comprises the focusing aperture in a multi-beam scanning antenna. The 61 cm diameter lens was fabricated from polyethylene and polystyrene dielectrics. The finite ground plane introduces a scanning loss since its truncation effectively reduces the aperture area: the effect becomes significant at low elevation angles. This scanning loss was investigated from a theory for the aperture plane distribution; measurements with the lens; and numerical modeling using the commercial solver FEKO. The lens gain is 35.5 dBi at 11.5 GHz, equivalent to a dish of similar area.