Calculation of the Radiation Pattern of Finite Size Planar Wavefront Resonance Antennas

A method considering the finite size of the radiation aperture for general types of planar antennas, like microstrip patches or high gain printed antennas, is presented. This method takes into account the modification of the radiation pattern of a 9-directed line source fed multilayer antenna structure by calculating the aperture tangential field corresponding to the exact antenna pattern applying to infinite apertures. By integrating over the physical aperture dimensions the modified radiation pattern due to the finite aperture size is obtained. Results for planar wavefront resonance antennas, which are capable of supporting strongly excited leaky waves, are presented and compared with methods, only applicable for this leaky wave antenna type. Experimental results obtained for these antenna structures radiating into broadside as well as scanning into 45° are given and compared with simulation.