A Systematic Design Method of Miniaturizing Microstrip Patch Antenna Using Theory of Characteristic Modes

A systematic design method of miniaturizing microstrip patch antenna using characteristic modes has been presented. The TCM is applied to investigate and control the currents to excite the lowest resonance mode of the rectangular patch. The first current mode, J1, showed horizontal current distribution, and J2 showed current distribution in the vertical direction of the width of the patch. A systematic analysis has been done to procure the desired excitement of the specific modes. The slot etching was used to elongate the current path first in vertical and then in horizontal directions of the width of the patch. The successful excitation of the lowest resonant mode, i.e., J1, was achieved by etching a slot parallel to the direction of J1. After optimization, the final version showed 60 % miniaturization than the original rectangular patch size with no significant deterioration in performance.