Layered Circular-Cylindrical Dielectric Lens Antennas-Synthesis and Height Reduction Technique

An accurate computer-aided-design tool has been developed for the synthesis of broadband layered circular-cylindrical dielectric lens antennas. It is based on the combination of a fast method of analysis formulated in the spectral domain with a global optimization algorithm based on the particle swarm optimization technique. Using this tool, the influence of the number of layers is studied for lenses of moderate size. We show that single-layer lenses with an optimum permittivity value have nearly the same radiation characteristics as optimized multi-layer configurations. Finally we introduce a new height reduction technique that allows reducing the lens size by almost a factor of two while retaining the fan-beam pattern capabilities of cylindrical lenses in the elevation plane as well as their axial-symmetry needed for beam scanning in the horizontal plane. Numerical results have been compared successfully with experimental ones from 26 to 40 GHz, to validate the analysis.