Multifrequency operation of microstrip antennas using aperture-coupled parallel resonators

A microstrip antenna composed of parallel dipole resonators of different lengths fed by a rectangular slot cut in the ground plane of a microstrip line is analyzed using an integral equation technique solved in the spectral domain using the Galerkin method of moments. Multifrequency operation of this antenna is demonstrated using two different configurations. Experimental data are shown to be in good agreement with predicted results. The fundamental parameters influencing the realization of multifrequency operation, as well as impedance matching of the different resonances, are studied. Lastly, the radiation patterns of the antenna at different frequencies and the relative contribution of the dipoles to the radiation are investigated