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 $\times58$ mm $\times 1$ 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 low envelop correlation coefficient (ECC) of lower than 0.04, high multiplexing efficiency ( $\eta _{\mathrm {mux}}$ ) 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.

中文翻译：

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采用风车形去耦结构的超宽带高隔离度MIMO天线系统

本文提出了一种新型的高隔离度超宽带多输入多输出（SWB-MIMO）天线系统，每个天线元件由一个铲形辐射贴片、一个缺陷接地结构（DGS）以及作为风车状的解耦结构。辐射贴片上蚀刻的椭圆槽和矩形DGS共同使用，以提高辐射性能和阻抗带宽。分别对四单元和八单元 SWB-MIMO 天线系统进行了仿真和分析。总尺寸为 58 mm 的四单元 SWB-MIMO 天线系统原型 $\times58$ 毫米 $\times 1$ mm 的制造是为了验证使用 FR4 材料基板的设计概念。测量和仿真结果表明，所提出的 SWB-MIMO 天线系统可以在 2.9 至 40 GHz 的频段内工作，互耦合低于–17 dB。此外，还以低于 0.04 的低包络相关系数 (ECC)、高复用效率 ( $\eta _{\mathrm {mux}}$ ) 超过 – 3.0 dB，高达 13.5 dBi 的稳定增益以及准全向辐射特性。该设计为获得超宽 MIMO 天线提供了重要指导。