Feed and loss effects in spherical lens antennas for satellite communications

The hemispherical lens antenna is a candidate for satellite communications-on-the-move, offering good scan performance in a reduced height. A short focal length minimizes height but presents challenges in illuminating the lens. Aperture efficiency is dominated by both the primary feed and dielectric loss. Feed effects are investigated in a threefold approach: spherical wave theory, commercial solver, and measurements. Gain and loss in a 432 mm diameter polyethylene/polystyrene lens are also measured. Gain for a waveguide-fed array of two lenses is 36.3, 38.8, and 41.1 dBi, respectively, at 12.5, 20, and 30 GHz. The performance of a proposed four-element array of equivalent area is then estimated.