On the Size Reduction of Slotted Finite Ground Plane of a Circularly Polarized Microstrip Patch Antenna Using Substructure Characteristic Modes

In this work, a miniaturized circularly polarized microstrip patch antenna with a slotted ground plane is designed by using substructure based theory of characteristic modes. The overall size of the antenna is miniaturized by systematically reducing the size of its ground plane. Circularly polarized nature of the antenna is achieved by properly shaping the slotted ground plane and the patch as well. The resonance behavior of the slotted ground plane is determined by its size as well as the shape of the patch. This phenomenon helps in achieving the size reduction of the ground plane by modifying the dimensions of embedded ground slots and controlling the size of the patch. It is found that substructure modal resonances can be positioned at desired frequencies by adjusting the size of ground slots and the patch even if a strong coupling exists between them.