A Hybrid Method of Analysis for Shaped Dielectric Lenses Compared with Measurement Results

A novel hybrid method to compute EM fields for a hemi-shaped lens based array antennas using modal analysis and geometrical optics over a near field spherical surface is presented in this paper. The near field of the array radiator is obtained from its far field pattern as a spherical modal expansion (SME). The requisite number of spherical modes characterizing the array are treated as co-located plane wave sources radiating into the shaped dielectric lens and analyzed using geometrical optics (GO). The total field at any point on a spherical surface surrounding the lens is the sum of individual plane wave contributions. These are easily transformed to far field using a SME. Presented in this effort are computations using the hybrid technique for hemi-spheroidal and hemi-spherical lenses irradiated by 1×2 and 2×2 array in C and X-bands that are compared with results using an EM Flow solver (HFSS). Significantly the hybrid procedure is validated with measured results obtained in an anechoic chamber that shows a far better agreement, as compared to EM flow solver. Notably the computation time required by hybrid method is nearly 18 times less compared to the simulation time of EM Flow solver.