Complex ray and evanescent wave analysis of parabolic reflector antennas

The Complex-Source-Point (CSP) method is applied to the analysis of the vector field reflected from a parabolic reflector antenna offset-fed by a Gaussian beam centered at the reflector focus. The asymptotic CSP solutions from both the general and paraxially approximated analysis have been implemented on a computer using numerical data from the literature. The results from the general procedure are compared at 28.5 GHz with those deduced by semi-heuristic superposition of ideal beam mode fields with even and odd vector symmetry, and with corresponding experimental data. The total field results show coincidence between the two analytical procedures for points down to -50 dB, and the agreement holds for cross-polarization patterns as well. The validity of a simplified paraxial analysis for the total field and the cross-polarization peaks is important for tractable applications to satellite communication systems since the relevant phenomena occur in the paraxial region.