Dual-Polarized Microstrip Patch Antenna Array with Dual-Feed for Target Detection

A planar antenna is designed to replace complex structures of many rat-race couplers and 90° hybrids used in conventional target detection antennas. The proposed antenna has 2 × 2 microstrip patch antenna arrays with dual feeding to radiate symmetric polarizations in the 9.375 GHz (X-band). The sum pattern with circular polarization is implemented through a sequence feeding at port 1. The simultaneous feeding of port 2 radiates a difference pattern in all polarizations. Thus, a target detection antenna is designed with features that have fewer ports than the conventional monopulse antennas. The proposed antenna is compact, planar, and has a simple comparator circuit and equal sum and difference levels. Also, in the last section, the antenna feeding network which can be receive the dual-CP (RHCP and LHCP) is proposed.