A 2 × 2 Self-Decoupling MIMO Patch Antenna Array With Stable Radiation Pattern

In this paper, a novel 2 × 2 MIMO patch antenna array with high port isolation, stable radiation pattern, and high gain of element has been proposed. The array is composed of four TM12 mode circular patches with 0.2 mm patch-to-patch separation. By loading double slots to the patch center of each element, it reduces the sidelobe level (SLL) of the TM12 mode of the circular patch antenna and lowers the lateral radiation, achieving the stable radiation pattern. And by reshaping the electric field distribution in the E-plane, the electric coupling of the array in the E-plane is further suppressed. The original weak-field regions of the TM12 mode circular patch contribute to the intrinsic high isolation of the H-plane coupled. The measurements show that the array can achieve intrinsic high isolation of more than 20 dB, element gain of 9.9 dBi, and cross-polarization level below -20 dBi without using any extra decoupling network.