A wide-band dual-polarized VHF microstrip antenna for global /sup s/ensing of sea ice thickness

A VHF microstrip patch antenna was developed to achieve a bandwidth of 45 MHz (300%) from 127 MHz to 172 MHz with dual-linear-polarization capability. This microstrip antenna uses foam substrates and dual stacked patches with capacitive probe feeds to achieve wide bandwidth. Four such capacitive feeds were used to achieve dual polarization with less than -20 dB of cross-polarization level. Twenty-four shorting pins were used on the lower patch to achieve acceptable isolation between the four feed probes. This antenna has a measured gain of 8.5 dB at 137 MHz and 10 dB at 162 MHz. By using the method of moments technique, multipath scattering patterns were calculated when the antenna is mounted on the outside of a Twin Otter aircraft.