Stacked microstrip antenna for wideband and high gain

The behaviour mechanism of the stacked antenna is synthetically clarified for the first time by investigating the results calculated using the FDTD method. The stacked microstrip antenna has particular characteristics, such as a high gain or a wide bandwidth. When the size of the parasitic patch, is nearly equal to the fed patch and the distance between the fed patch and the parasitic patch is approximately 0.1 wavelength, the bandwidth is increased. When that distance is approximately half a wavelength, the gain enhancement is obtained. The wide bandwidth and the gain enhancement are considered synthetically by the detailed investigation of calculated results including the near-field distributions. It is shown that the wide bandwidth and the gain enhancement are caused by a two-frequency resonance and leaky resonant cavity formation, respectively. The calculated input impedance and radiation patterns agree well with the experimental values.