Full-wave analysis and wide-band design of probe-fed multilayered cylindrical-rectangular microstrip antennas

The input impedance and radiation pattern of the probe-fed multilayered cylindrical-rectangular microstrip antennas (PMCMSA) are analyzed by using a novel approach which combines the conformal finite-difference time-domain (FDTD) and Gedney's unsplit version of the perfectly matched layer absorbing boundary condition method and the Green's functions in cylindrically stratified media. The near fields of such antennas and the current distributions on the patches are obtained by the conformal FDTD method numerically and then the modified spectral-domain Green's functions in arbitrary cylindrically stratified media are used to determine the radiation pattern. The effect of the small radius of the probe on the performance of antennas is investigated through the thin-wire algorithm in cylindrical coordinates. A simple design scheme of the probe-fed cylindrically stacked antennas is also proposed for increasing the impedance bandwidth.