A four-element frequency reconfigurable and pattern diverse multiple-input–multiple-output (MIMO) antenna array for fifth-generation relay node applications is presented to operate in LTE bands 42 (3400–3600 MHz), 43 (3600–3800 MHz), and 46 (5150–5925 MHz). A planar microstrip line-fed monopole antenna is utilized as the MIMO element. The antenna relies on fluidic reconfiguration mechanism to either serve LTE bands 42/43 or 46. It incorporates a substrate milled channel beneath each monopole arm to hold distilled water. The water in the channel perturbs the $E$ -field distribution in the vicinity of the antenna arm and modifies the effective permittivity of the dielectric medium. To realize pattern diversity, adjacent elements are placed orthogonal to each other. Measured prototype exhibits a total active reflection coefficient $|{\text{TARC}}|$ and $|S_{11} |\leq -10$ dB for the high band when the channel is vacant (case 1) and the low band when filled with water (case 2), while minimum isolation is above 19.6 dB. The peak measured gain is ~4.6 and ~2.8 dBi, while the worst case envelope correlation coefficient (ECC) is ~0.004 and ~0.016 for cases 1 and 2, respectively. It measures 82.4 $\times$ 82.4 mm2 and was fabricated on a 1.52-mm-thick substrate of $\epsilon_{r}$ = 3.55.

中文翻译：

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适用于 6GHz 以下 5G 中继节点应用的具有模式多样性的流体可重构 MIMO 天线

提出了一种用于第五代中继节点应用的四元素频率可重构和模式不同的多输入多输出 (MIMO) 天线阵列，可在 LTE 频段 42 (3400–3600 MHz)、43 (3600–3800 MHz) 中运行, 和 46 (5150–5925 MHz)。平面微带线馈单极天线用作 MIMO 元件。天线依赖于流体重构机制来服务于 LTE 频段 42/43 或 46。它在每个单极臂下方结合了一个基板研磨通道，以容纳蒸馏水。通道中的水扰乱了 $E$ -天线臂附近的场分布并修改电介质的有效介电常数。为了实现模式多样性，相邻元素彼此正交放置。测量的原型展示了一个总的有源反射系数 $|{\text{TARC}}|$ 和 $|S_{11} |\leq -10$ 信道空闲时的高频段（情况 1）和充满水时的低频段（情况 2）的 dB，而最小隔离度高于 19.6 dB。测得的峰值增益为 ~4.6 和 ~2.8 dBi，而最坏情况的包络相关系数 (ECC) 分别为案例 1 和案例 2 的 ~0.004 和 ~0.016。它的测量值为 82.4 $\times$ 82.4 mm2 并在 1.52 mm 厚的基板上制造 $\epsilon_{r}$ = 3.55。