Local optimization of mm-wave integrated lens antennas

A design methodology of optimized homogeneous dielectric lens antennas is proposed. The procedure comprises two successive stages. Geometrical Optics (GO) principles are firstly implemented to determine the best lens profile that radiates a specified amplitude-shaped output pattern. Then this GO solution serves as an initial condition to optimize the lens shape using an analysis kernel based on the standard diffraction integral. For that purpose, the optimizer uses a multi-dimensional Conjugate Gradient Method with Ribiere-Polak parameters for a fast convergence of the algorithm. Experimental results obtained at 58.5 GHz with non-optimized and optimized Teflon lenses successfully validate our modelling tools for the analysis, the synthesis and the optimization of arbitrarily-shaped 3D single refractive surfaces.