A compact two‐element multiple‐input multiple‐output (MIMO) antenna is proposed for triple‐band applications with very high port isolation. The structure is constructed in‐house with a flexible biomass material which is coconut husk. Two metallic “8”‐shaped antenna structures are employed manually on the substrate to serve as MIMO elements. Frequency bands of the antenna for (S₁₁ ≤ −10 dB) are obtained from 2.04 to 2.51 GHz, 4.43 to 5.35 GHz, and 6.76 to 8.78 GHz. The antenna fulfills the wireless local area network (WLAN) (2.4‐2.485/5.15‐5.35 GHz), fixed‐mobile (4.45‐5.15 GHz), and International telecommunication union (ITU) (8‐8.5 GHz) application bands. A stub with three sub‐sections is integrated in the ground to improve the overall triple‐band port isolation characteristics. It is found that the minimum port isolation for entire application bands is greater than 20 dB. This low correlation between the elements is further confirmed by low value of envelope correlation coefficient (ECC < 0.14) and high value of diversity gain (DG > 9.98 dB). Channel capacity loss (CCL < 0.22 bit/s/Hz) and mean effective gain (MEG = ±0.19 dB) are also found within acceptable ranges. Characterization of the substrate material of the proposed MIMO antenna is rigorously investigated by analyzing its dielectric constant and loss tangent. Simulated and measured results ratify that the antenna is fit for triple‐band MIMO applications.

中文翻译：

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紧凑的MIMO天线具有高端口隔离度，专为三频应用而设计，采用椰子壳制造的生物质材料设计

提出了一种紧凑的两元素多输入多输出（MIMO）天线，用于端口隔离度很高的三频应用。该结构是使用椰子壳等柔性生物质材料在内部建造的。在基板上手动采用两种金属的“ 8”形天线结构作为MIMO元件。用于（S ₁₁的）天线的频带 ≤-10 dB）是从2.04至2.51 GHz，4.43至5.35 GHz和6.76至8.78 GHz获得的。天线满足无线局域网（WLAN）（2.4-2.485 / 5.15-5.35 GHz），固定移动（4.45-5.15 GHz）和国际电信联盟（ITU）（8-8.5 GHz）应用频段。具有三个子部分的存根集成在地面中，以改善整体三频端口隔离特性。发现整个应用频段的最小端口隔离度大于20 dB。元素之间的这种低相关性通过包络相关系数的低值（ECC <0.14）和分集增益的高值（DG> 9.98 dB）进一步得到证实。信道容量损耗（CCL <0.22 bit / s / Hz）和平均有效增益（MEG =±0.19 dB）也在可接受的范围内。通过分析其介电常数和损耗角正切，对所提出的MIMO天线的衬底材料进行了严格的研究。仿真和测量结果证明该天线适合三频MIMO应用。