A wideband multiple-input multiple-output (MIMO) antenna for C-band applications is presented in this paper. It consists of 2 × ${\times}$ 1 hexagonal motifs which serves as radiating elements. The side of each hexagonal element is 5.73 mm and the overall dimension of the proposed MIMO antenna is 30 × ${\times}$ 20 × ${\times}$ 1.6 mm3. The hexagonal motifs are embedded on inexpensive FR-4 lossy substrate. Thereafter, a circle with radius 1 mm is etched at the center of each hexagonal motif. Inverted L-shaped stubs are employed to attain efficient isolation between the nearby antenna elements. Four inverted L-shaped stubs are included to further enhance the isolation and eliminate the antenna size increment simultaneously, by suppressing the surface waves. Before using the decoupling approach, the MIMO antenna had an impedance bandwidth of 6.7 GHz and an isolation of −20 dB. The suggested antenna’s impedance bandwidth and isolation are 5.83 GHz and −52 dB, respectively, after using a decoupling approach (inverted L-shaped stub). The proposed MIMO antenna had a peak gain and radiation efficiency of 3–7 dBi and better than 90% (with decoupling), 2.75 to 6 dBi and greater than 60% (without decoupling). To verify the proposed design, a prototype was developed to compare the simulated parameters with the measured one. The envelope correlation coefficient (ECC) was less than 0.05, and channel capacity loss (CCL) less than 0.3 was achieved with DGS. Besides, scattering matrix such as return loss S 11 and transmission coefficient S 21 between two elements, radiation pattern, and current distribution was also favorable. Thus, the proposed MIMO antenna is advantageous to be used for C-band applications such as developing new generation air-borne and space-borne radars, as well as X-band applications.

中文翻译：

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基于 DGS 的小型化宽带 MIMO 天线，具有适用于 C 波段应用的高效隔离

本文介绍了一种用于 C 波段应用的宽带多输入多输出 (MIMO) 天线。它由 2 × ${\次}$ 1 用作辐射元素的六角形图案。每个六边形单元的边长为 5.73 mm，提出的 MIMO 天线的整体尺寸为 30 × ${\次}$ 20 × ${\次}$ 1.6 毫米3. 六边形图案嵌入廉价的 FR-4 有损基材上。此后，在每个六边形图案的中心蚀刻一个半径为 1 mm 的圆。采用倒置的 L 形短截线来实现附近天线元件之间的有效隔离。包括四个倒 L 形短截线，通过抑制表面波，进一步增强隔离并同时消除天线尺寸增量。在使用去耦方法之前，MIMO 天线的阻抗带宽为 6.7 GHz，隔离度为 -20 dB。在使用去耦方法（倒 L 形短截线）后，建议天线的阻抗带宽和隔离度分别为 5.83 GHz 和 -52 dB。所提出的 MIMO 天线具有 3-7 dBi 的峰值增益和辐射效率，并且优于 90%（有去耦），2。75 至 6 dBi 和大于 60%（无去耦）。为了验证所提出的设计，开发了一个原型来将模拟参数与测量参数进行比较。DGS的包络相关系数（ECC）小于0.05，信道容量损失（CCL）小于0.3。此外，散射矩阵，如回波损耗小号 11和传输系数小号 21两个元素之间的辐射方向图和电流分布也是有利的。因此，所提出的 MIMO 天线有利于用于 C 波段应用，例如开发新一代机载和星载雷达，以及 X 波段应用。