Input impedance and cross polarization studies of EMCP antennas

Experimental results on the input impedance characteristics of the two-layer electromagnetically coupled patch antenna as a function of feed position and layer spacing are presented. The input resistance is shown to increase as the feed is moved away from the center. For a given feed location, the input resistance decreases with increasing Delta (air gap spacing). Results on the cross polarization level of the antenna are also reported. The cross polarization level was found to change somewhat with Delta . However, for the range of values studied, it remained at least 30 dB below the copolarization level at boresight, provided the feed location from the center is chosen so that the return loss is >or=10 dB.<>