A 4*4 multiple-input multiple-output (MIMO) antenna with compact size and good isolation is presented for UWB applications. The concept of polarization diversity is here discussed and employed to satisfy contemporary wireless communication systems requirements. In the proposed antenna, the utilization of a novel circular ripple-shaped decoupling structure and a matching structure are presented to minimize mutual coupling of the inter-elements and enhance adaptation. Experimental results show a bandwidth range from 2.96 to 11.4 GHz with a good reflection coefficient which is S 11 < −12 dB, high isolation S 21 and S 31 < −20 dB, good Envelope Correlation Coefficients ECC21 and ECC31 < 0.03, Diversity Gain DG21 and DG31 equal to 8.75, and a Total Active Reflection Coefficient (TARC) less than −12 dB. The antenna also exhibits a maximum gain of about 4 dBi with a maximum efficiency of 70% which proves that this antenna is a potential candidate for UWB applications.

中文翻译：

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在四元件 UWB MIMO 天线设计中使用新型圆形波纹状去耦机制减少耦合

为 UWB 应用提供了具有紧凑尺寸和良好隔离度的 4*4 多输入多输出 (MIMO) 天线。这里讨论并采用极化分集的概念来满足当代无线通信系统的要求。在所提出的天线中，提出了一种新颖的圆形波纹状去耦结构和匹配结构的利用，以最大限度地减少元件间的相互耦合并增强适应性。实验结果表明，带宽范围为 2.96 至 11.4 GHz，具有良好的反射系数，S 11 < -12 dB，高隔离度 S 21 和 S 31 < -20 dB，良好的包络相关系数 ECC21 和 ECC31 < 0.03，分集增益 DG21 DG31 等于 8.75，总有源反射系数 (TARC) 小于 −12 dB。