A reciprocity method of analysis for printed slot and slot-coupled microstrip antennas

A method is presented for the analysis of slot-type discontinuities in microstripline. The approach is based on the reciprocity theorem and uses the exact Green´s functions for the grounded dielectric slab in a moment method solution for the unknown antenna currents. The method is applied to two specific geometries: a radiating slot in the ground plane of a microstripline, and an aperture coupled microstrip patch antenna. Results for antenna impedance are compared with measurements, and far-zone patterns are calculated. The method is shown to be quite versatile, and should find application to related problems.