Multi-resonator gap-coupled variations of microstrip antennas backed by rectangular slot cut ground plane

Novel gap-coupled variations of rectangular and circular microstrip antennas backed by rectangular slot cut ground plane are proposed. The slot on the ground plane below each of the patch, reduces the resonance frequency of the fundamental mode, thereby giving wideband response at the reduced frequency. With reference to the gap-coupled design at reduced frequency using the conventional ground plane, a slot cut ground plane design yields a reduction in the total patch area with higher BW and comparable gain values. On thinner Taconic substrate (h < 0.02 lambda(g)), using rectangular and circular patches, the optimum result is obtained with parasitic patches gap-coupled along the two diagonal axis. In the rectangular patch design, bandwidth of 148 MHz (6.04%), peak gain of 9 dBi, for patch size reduction of 33.33% is achieved, whereas using the circular patches, these values are, 138 MHz (5.48%), 9.2 dBi and 38.4%, respectively. In all the proposed gap-coupled designs, for the maximum possible frequency reduction, BW and gain realized is higher as compared with the gap-coupled design with a normal ground plane.