Synthesis of dual band broadside radiated microstrip patch antenna operating with TM/sub 10/ and TM/sub 21/ modes

A novel concept for the synthesis of linearly polarized broadside radiated dual band microstrip patch antenna is presented. The approach uses the basic and suitable higher modes of a patch resonator that are modified by an appropriate patch surface perturbation so that the outbalancing current component in the direction of the demanded polarization is dominant at both design frequencies. This concept is different from standard approaches that use additional passive resonators in the same metal level as the fed patch or in other layers in the so-called stacked arrangement, or another frequently used concept that modifies the patch by introducing suitably shaped perturbing elements, such as slots and notches. These standard approaches have a common feature, namely that additional basic modes or basic resonances of parasitic parts are excited. The proposed novel approach has been verified on a model of a dual band 3.5/5.5 GHz microstrip patch antenna. The basic TM/sub 10/ mode and the higher TM/sub 21/ mode of a patch modified by two T-slots has been used to achieve dual band resonance with linear polarization in both frequency bands. The final antenna shape was acquired by an optimization approach that combines genetic algorithm/gradient optimization Matlab script and numerical analysis by 3D planar IE3D simulator.