A small complementary split ring resonator loaded circularly polarized patch antenna

Size reduction of patch antennas by loading them with complementary split ring resonators (CSRRs) has been recently demonstrated for linearly polarized radiators. This paper demonstrates that the design approach can be extended for circularly polarized radiation by employing multiple CSRRs under the patch to generate a 900 rotationally symmetric antenna structure. It is also shown that, in this antenna configuration, the radiation efficiency becomes strongly dependent on the size of the ground plane that carries the CSRR metallization. To further miniaturize the antenna size without affecting its radiation efficiency, we develop a new antenna structure in which the CSRRs are formed within a truncated ground plane loaded with vertical inductive pins. The antenna operates at 2.24GHz with peak broadside realized RHCP gain of 3dB, corresponding to 75% radiation efficiency.