A hybrid method of analysis of shaped dielectric lens antennas

A hybrid of spherical modal analysis and geometrical optics based computation of EM fields over a near field spherical surface surrounding the lens antenna is presented. The near field of the primary radiator is obtained from a spherical modal expansion (SME) of its far field pattern. The principal component of a requisite number of spherical modes are then treated as co-located sources radiating into the shaped dielectric lens and analyzed using geometrical optics. The total field at any point on a spherical surface surrounding the lens is the sum of individual modal contributions, which are then easily transformed to far field using a SME. This method is independent of lens geometry and computationally rapid compared to Method of Moments (MoM) employed by EM flowsolvers. As expected the prediction accuracy is between that of an exact SME technique and an EM flowsolver as seen for spherical lens geometry. Results have been presented for an array with spherical and hemi-spheroidal lenses.