A study of annular ring patch microstrip antenna shorted at the outer periphery

The input impedance, resonant frequency, and radiation characteristics of the annular ring patch microstrip antennas shorted at the outer periphery are studied. Analytic results for the dominant and higher-order modes are compared with experimental data and previous results. The radiation conductance, the fringing field, and the effect of feed position, i.e., a coaxial probe, are included in the analysis. Two antennas, A and B, were fabricated and tested. Their calculated resonant frequencies for the TM/sub 11/ mode are 2.174642 GHz and 3.143697 GHz for model A and model B, respectively, which agree well with the measured ones, 2.19913 GHz and 3.15452 GHz, respectively.<>