FDTD analysis of wide-band circular and annular-ring patch antennas

A finite-difference time-domain (FDTD) analysis of gap-coupled circular patch antennas (GCCPA) on isotropic substrates is presented. The return loss, the input impedance and the radiation pattern are determined. Similar analysis is performed for the stacked-gap coupled (SGC) annular-ring microstrip antennas. About 40% -10 dB bandwidth is achieved which is eight times more than that of the single annular-ring antenna. The results obtained by the FDTD method are found to be in good agreement with the published data.