High Isolation UWB-MIMO Compact Micro-strip Antenna

A compact four-unit ultra-wideband multiple-input multiple-output (UWB-MIMO) antenna with very high isolation, dual polarization, notched structure, and achieving dual-state operation, along with smaller volume, is proposed in this paper. The proposed MIMO antenna element consists of two parts: the front patch composed of four symmetrical trapezoidal radiating elements and feeder, and the back composed of a rectangular annular ground. The offset of antenna operating frequency band is achieved by adjusting the rectangular patch in the middle of the back side, and by introducing an X-shaped metal narrow strip on the top side and an X-shaped slit on the bottom side to improve the isolation in the single port feeding state of antenna. Finally, the dimension of the antenna is 32 x 32mm(2). Under the frequency from 3.1 GHz to 10.6 GHz, the isolation in the condition of differential mode can below -30 dB, which is very high, and also can work in the single port inputting state, showing a dual mode operation. In addition, a trapezoidal slit is introduced to obtain a notch structure. The measured results and simulation results are consistent.