面向体表通信的透明柔性全向圆极化可重构天线

      Transparent and flexible antenna with omnidirectional circular-polarization reconfigurability for on-body communications

      • 摘要: 根据无线体域网体表通信的需求和复杂的人体表面应用场景,结合介质谐振器和等效电流环,提出了一款透明柔性的全向圆极化可穿戴天线,并拓展了其圆极化可重构功能。圆柱形介质谐振器的TM01δ模式和接地近似L形枝节上的环形电流分别产生电场的EθEφ分量,两分量幅值相等、相位相差 90\text° ,实现了全向圆极化。天线的–10 dB阻抗带宽覆盖5.8 GHz的工业、科学和医用(industrial, scientific and medical, ISM)频段,通过机械旋转可以在全向左旋圆极化和全向右旋圆极化间切换,两状态下的轴比相对带宽分别为10.9%和10.8%。在5.8 GHz频点,最大辐射方向( \theta = 50\text° 面)的3 dB轴比波束宽度达到了 360\text° 全覆盖。介质谐振器和接地枝节分别由聚二甲基硅氧烷和导电网格布构成,在保证天线舒适性、透明性和隐蔽性的同时实现了59%的辐射效率和2.6 dBic的增益。利用3D打印技术加工天线样本,并通过测试验证了设计的合理性。

         

        Abstract: Aiming at the requirements of on-body communications and complex on-body application scenarios in wireless body area network (WBAN), a transparent and flexible wearable antenna with omnidirectional circular polarization (CP) is developed, based on the dielectric resonator (DR) loaded with an equivalent current loop. And, the reconfiguration of CP is further implemented. Radiated electric field components of Eθ and Eφ are generated by the TM01δ mode of the cylindrical DR and the loop current of the grounded L-shaped branches, respectively. Omnidirectional CPs are realized when the two components are equal in magnitude but differ in phase by 90\text° . The proposed antenna can be switched between left- and right-handed circularly polarized omnidirectional radiations through mechanical rotation, with –10-dB impedance bandwidth covering the 5.8 GHz Industrial, Scientific, and Medical (ISM) band. The 3-dB axial ratio (AR) bandwidths at 5.8 GHz of two states are 10.9% and 10.8%, respectively. The DR and grounded branches are constructed of polydimethylsiloxane (PDMS) and conductive mesh fabric, respectively. The radiation efficiencies of 59% and gains of 2.6 dBic are enabled, together with the advantages of comfort, transparency, and concealment. And, the 3-dB AR beamwidth in the θ = 50° plane achieves a full coverage of 360\text° . Antenna prototypes were fabricated with the aid of 3D printing technology and the proposed design was verified through tests.

         

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