A Super-Wideband And High Isolation Mimo Antenna System Using A Windmill-Shaped Decoupling Structure

In this paper, a novel super-wideband multiple-input multiple-output (SWB-MIMO) antenna system with high isolation has been proposed, each antenna element consisting of a spade-shaped radiation patch, a defected ground structure (DGS) as well as a windmill-shaped decoupling structure. The elliptical slot etched on the radiation patch and the rectangular DGS are jointly utilized to make better the radiation performance and impedance bandwidth. Both of four-element and eight-element SWB-MIMO antenna systems are simulated and analyzed, respectively. A prototype of the four-element SWB-MIMO antenna system with total dimensions of 58 mm x 58 mm x 1 mm was fabricated to verify the concept of design using an FR4 material substrate. Measurement and simulation results indicate that the proposed SWB-MIMO antenna system can work in the frequency band ranging from 2.9 to 40 GHz with a mutual coupling of lower than -17 dB. Also, excellent performance has been achieved with a lowenvelop correlation coefficient (ECC) of lower than 0.04, high multiplexing efficiency (eta(mux)) of more than-3.0 dB, stable gain of up to 13.5 dBi as well as quasi-omnidirectional radiation properties. This design provides an important guideline for obtaining a super-wide MIMO antenna.