Optimal design of wideband microstrip arrays with high aperture efficiency on FR4 substrate

Two novel two-dimensional wideband arrays of microstrip E shaped patches are designed for use in a 10 % frequency range around the 2.45 GHz ISM band. The main design criterion was a combination of this bandwidth with an aperture efficiency as high as possible, since this allows to minimize occupied space. The design is based on a Method of Moments algorithm in combination with a Particle Swarm Optimization. CST MW Studio was employed for validation purposes. A very good agreement was achieved between simulated results. The maximum simulated aperture efficiency of the last array is 84 %, which is considerably higher than what has been reported up to now in literature for wideband microstrip arrays.