Slot loaded square patch antenna with CSRR at ground plane

Various approaches have evolved for the improvement of the performance of microstrip antennas like modifying geometry of the patch, using multilayered substrate, cutting out slots of different shapes from the patch or the ground plane etc. Of late, metamaterial inspired designs are receiving greater attention. The present work focuses on a combination of traditional approach of slot based design and a contemporary approach based on metamaterial structure. A rectangular slot is etched from a square patch antenna of each side 12.5 mm and a complementary split ring resonator (CSRR) structure is etched from the ground plane just below the patch. The CSRR reduces the fundamental resonant frequency of the antenna thereby lowering the electrical size by 13.5%. When slotted is loaded on the patch along with the CSRR at ground plane, there is further improvement in the performance. The combination of the slot and the CSRR yields an overall enhancement of the performance of antenna in terms of reduced electrical size by about 14.5%, increases far field gain by approximately 2 dB, lowers the return loss by 8 dB.