In this letter, a low-profile wideband pattern diversity antenna based on metasurface (MTS) is proposed. Initially, based on the theory of characteristic mode (TCM), the two adjacent intrinsic modes, which correspond to the broadside and conical radiation pattern, respectively, are exploited to realize a wideband pattern diversity characteristic under a low profile. Then, by analyzing the modal current distribution on the MTS, the optimal locations, orientations and relative phases of the four L-shaped feeding probes are determined to excite the above two modes. However, the in-band high-order modes (HOMs) introduced by the feeding structure will deteriorate the radiation pattern. Therefore, chamfering corners on the MTS is used to suppress the HOMs for radiation pattern improvement. Finally, by combining TCM and MTS, the modes are manipulated to achieve a pattern diversity antenna with an extremely low profile of 0.06 λ ₀ (the free-space wavelength at the center frequency) and an isolation of better than 38 dB, which also maintains an operating bandwidth of 20.24%. Based on these excellent performances, the proposed antenna is an attractive solution for pattern diversity applications requiring low profile, especially in unmanned aerial vehicle communications.

中文翻译：

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基于超表面的低剖面宽带方向图分集天线

在这封信中，提出了一种基于超颖表面（MTS）的低调宽带模式分集天线。最初，基于特征模式（TCM）的理论，利用分别对应于宽边和锥形辐射图的两个相邻固有模式，来实现低剖面下的宽带图分集特性。然后，通过分析MTS上的模态电流分布，确定四个L形馈电探针的最佳位置，方向和相对相位，以激发上述两种模式。但是，由馈电结构引入的带内高阶模（HOM）将使辐射方向图恶化。因此，MTS上的倒角用于抑制HOM，以改善辐射方向图。最后，通过结合中医和MTS， ₀（中心频率处的自由空间波长）且隔离度优于38 dB，这也保持了20.24％的工作带宽。基于这些出色的性能，所提出的天线是要求低剖面的模式分集应用（特别是在无人机通信中）的一种有吸引力的解决方案。