Dual Polarization Stacked Microstrip Patch Antenna Array With Very Low Cross-Polarization

This paper describes the development and performance of a wideband dual linear polarization microstrip antenna array used in the Danish high-resolution airborne multifrequency polarimetric synthetic aperture radar, EMISAR. The antenna was designed for an operating frequency of 1.25 GHz 50 MHz and was built as an array of 8 2 probe-fed stacked microstrip patches. The feeding network is constructed in microstrip and is capable of handling 6 kW of peak input-power at an altitude of 45 000 ft (unpressurized). The impedance bandwidth (return-loss better than 14 dB) of the antenna is 10%, the isolation between the horizontal and the vertical ports of the array is 50 dB and the cross-polarization suppression is 40 dB. A new design principle for simultaneously achieving very low cross-polarization and low side lobes in dual linear polarization antenna arrays has been applied.