Reduced Cross-Polarization and Backside Radiations for Rectangular Microstrip Antennas Using Defected Ground Structure Combined With Decoupling Structure

For cross-polarization (XP) reduction of microstrip antenna, it is proposed to use asymmetric defected ground structure (DGS) under the patch, which perturbs the TM₀₂ mode. Unlike conventional DGS, the proposed DGS reduces the XP without increasing the back radiation. A method of higher order modes and surrounding electric fields is used to explain the DGS. The feasibility and superiority of the proposed scheme are further verified by constructing H-plane linear 4-element arrays. The XP reduction and decoupling are achieved simultaneously, as supported by simulation and measurement.