A compact pattern reconfigurable antenna with four radiation patterns is proposed for sub-GHz IoT applications. The antenna has two functional modes; Mode I has three uncorrelated patterns, while Mode II has electric and magnetic omnidirectional patterns. The resonant frequency of the antenna is 868 MHz with measured overlapped -6 dB impedance-bandwidths of 22 MHz and 20 MHz for Mode I and Mode II, respectively. The antenna is integrated in an 80×55 mm2 terminal. The radiating elements consist of two meandered slots and one meandered monopole. Four pattern configurations are obtained with an average peak gain of 0 dBi, and an average radiation efficiency of 43.3%. Two of the patterns are with 5 dB directivity, and the other two are omnidirectional patterns. Pattern reconfigurability is achieved using four PIN diodes. The antenna is fabricated on a low-cost FR-4 substrate. By removing FR-4 material inside the slots, slots' radiation efficiencies were improved by 2.25 dB.

中文翻译：

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适用于 Sub-GHz 物联网应用的具有四种辐射模式的多功能紧凑型可重构天线


为 sub-GHz 物联网应用提出了一种具有四种辐射方向图的紧凑型可重构天线。天线有两种功能模式；模式 I 具有三个不相关模式，而模式 II 具有电和磁全向模式。天线的谐振频率为 868 MHz，模式 I 和模式 II 的测量重叠 -6 dB 阻抗带宽分别为 22 MHz 和 20 MHz。天线集成在 80×55 mm2 终端中。辐射元件由两个曲折槽和一个曲折单极子组成。获得了四种方向图配置，平均峰值增益为 0 dBi，平均辐射效率为 43.3%。其中两个方向图具有 5 dB 方向性，另外两个方向图是全向方向图。使用四个 PIN 二极管可实现模式可重构性。该天线是在低成本 FR-4 基板上制造的。通过去除缝隙内的 FR-4 材料，缝隙的辐射效率提高了 2.25 dB。