Reduction of Internal Reflections in Inte- Grated Lens Antennas for Beam-steering

The conventional integrated lens antennas (ILAs) for beam steering suffer from internal reflections that deteriorate the scanning properties. The internal reflections are known to affect side lobes, cross-polarisation level, input impedance of the feed, and mutual coupling. In this paper, ILAs are designed to exhibit very low reflection loss, i.e., to minimize the internal reflections. Wide ranges of realistic relative permittivities of the lens and of the feed element directivities are considered. It is shown that with any permittivity and with any feed directivity it is possible to design the lens shape in such a way that the reflection loss is low, for moderate beam-steering angles, without resorting to a complicated matching layer. The gain, directivity, beam-width, and the resulting distance between the feed elements are compared for all the designed lenses.