Performance Optimization of a Microstrip Patch Antenna using Characteristic Mode and D/Q Analysis

A >gt30% 2:1 VSWR bandwidth using a coaxially fed microstrip patch antenna along the patch diagonal has been designed within the framework of two optimization techniques and is the focus of this work. For a center frequency (f
_c
) of 3.6 GHz, 53.5% bandwidth is achieved when the feed probe is placed at 2/ 3
^rd
distance along the diagonal compared to a 15.7% bandwidth obtained, using the conventional offset fed design. Full wave simulation results are obtained by the FEKO solver and compared with measured data. Characteristic Mode Analysis (CMA) has been performed to identify the dominant eigencurrent modes, in the designed antennas. The approximate Quality Factors Q, applicable to electrically small antennas (ESAs), have been compared to the exact Q of the antenna calculated via antenna input impedance. Performance optimization of the antenna, in terms of both near- and far-field parameters, using the D/Q element optimization technique, has been investigated.