This paper presents a close-spaced dual-band 2 × 2 multiple-input multiple-output (MIMO) antenna with high isolation based on half-mode substrate integrated waveguide (HMSIW). The dual-band operation of the antenna element is achieved by loading a rectangular patch outside the radiating aperture of an HMSIW cavity. The HMSIW cavity is excited by a coaxial probe, whereas the rectangular patch is energized through proximity coupling by the radiating aperture of HMSIW. The antenna elements can be closely placed using the rotation and orthogonal arrangement for a 2 × 2 array. Small neutralization lines at the center of the MIMO antenna can increase the isolation among its elements by around 10 dB in the lower band and 5 dB in the higher band. A prototype of the MIMO antenna is fabricated and its performance is measured. The measured results show that the resonant frequencies are centered at 4.43 and 5.39 GHz with bandwidths of 110 and 80 MHz and peak gains of 6 and 6.4 dBi, respectively. The minimum isolation in both bands is greater than 35 dB. The envelope correlation coefficient is lower than 0.005 within two operating bands.

中文翻译：

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基于半模SIW的紧凑型高隔离度双频2×2 MIMO天线

本文提出了一种基于半模衬底集成波导（HMSIW）的具有高隔离度的近距离双频2×2多输入多输出（MIMO）天线。天线元件的双频操作是通过将矩形贴片加载到HMSIW腔的辐射孔的外部来实现的。HMSIW腔由同轴探针激发，而矩形贴片则由HMSIW的辐射孔通过邻近耦合激励。对于2×2阵列，可以通过旋转和正交布置将天线元件紧密放置。MIMO天线中心的小型中和线可以在较低频段将其元件之间的隔离度提高约10 dB，在较高频段将隔离度提高5 dB。制造了MIMO天线的原型，并对其性能进行了测量。测量结果表明，谐振频率的中心频率为4.43和5.39 GHz，带宽分别为110和80 MHz，峰值增益分别为6和6.4 dBi。两个频带中的最小隔离度均大于35 dB。包络相关系数在两个工作频段内均低于0.005。