A compact single layer frequency reconfigurable Yagi-like multiple-input multiple-output (MIMO) antenna system is presented based on a half-ring closed loop slot excitation. The traditional omnidirectional pattern of a slot antenna is made directional by using a single slot-based complementary wideband reflector (CWBR) element. The proposed CWBR is compact in size, simple in construction, and is based on a single-layer geometry unlike complex multi-layer reflectors used in the literature. It improves the front-to-back ratio between 5 and 17 dB in the entire frequency range covering 2.5–4.5 GHz. The proposed reconfigurable MIMO antenna system covers the LTE and WiMAX bands with a minimum measured bandwidth of 200 MHz per covered bands. The frequency reconfigurability is achieved by reactively loading the slot loop with varactor diodes. The overall size of the proposed antenna system is , making it suitable for tablet handheld devices and access points. It has a maximum measured peak gain of 5 dBi and total measured radiation efficiency of 78%. The proposed MIMO antenna system has port isolation of 10 dB within the entire band of operation. The radiation patterns are isolated in space from each other and ensure very low envelope correlation coefficient.

中文翻译：

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具有宽带反射器的频率可重构的类似八木的MIMO天线系统

提出了一种基于半环闭环缝隙激励的紧凑型单层频率可重构八木类多输入多输出（MIMO）天线系统。通过使用单个基于缝隙的互补宽带反射器（CWBR）元件，可以将缝隙天线的传统全向方向图定向。所提出的CWBR尺寸紧凑，结构简单，并且基于单层几何结构，与文献中使用的复杂多层反射器不同。在覆盖2.5–4.5 GHz的整个频率范围内，它将前后比提高了5至17 dB。拟议的可重配置MIMO天线系统覆盖LTE和WiMAX频段，每个覆盖频段的最小测量带宽为200 MHz。频率可重构性是通过将变容二极管被动地加载到缝隙环路中来实现的。 ，使其适用于平板电脑手持设备和接入点。它的最大测得峰值增益为5 dBi，测得的总辐射效率为78％。拟议的MIMO天线系统的端口隔离为 在整个工作频段内为10 dB。辐射图在空间上彼此隔离，并确保非常低的包络相关系数。