应用于无线体域网的流体可重构穿戴天线

Fluid-Reconfigurable Wearable Antenna for Wireless Body Area Networks

摘要: 本文提出了一种应用于无线体域网的流体可重构穿戴天线。该天线以腰带配饰作为载体满足了佩戴舒适和隐蔽的需求，采取SMA耦合馈电拓展阻抗带宽解决以阻抗带宽与轴比带宽不匹配的问题。结合特征模分析通过二甲基硅油和乙酸乙酯这两种液体介质合理的填充替代传统切角微扰法引入的不对称结构，实现一对等幅度正交同相位的简并模分离成等幅度正交且相位相差90˚的特征模以实现圆极化特性(AR < 3 dB)，并且通过填充方式的切换实现轴比为线极化(AR = 40 dB)与圆极化(AR < 3 dB)的可重构。在圆极化的前提条件下，通过改变两种液体的填充比例实现谐振频率的可重构，轴比带宽的频率调谐范围为2.22 GHz~2.53 GHz。每一个轴比带宽都被阻抗带宽完全覆盖且轴比带宽内法向增益最高可达6 dB以上，规避了传统固体天线采用PIN二极管、变容二极管、MEMS实现可重构所引起额外的功率损耗等弊端。

Abstract: In this paper, a fluid reconfigurable wearable antenna for wireless body area network is proposed. The antenna uses a belt accessory as a carrier to meet the needs of wearing comfort and concealment, and adopts SMA coupling feed to expand the impedance bandwidth to solve the problem of mismatch between the impedance bandwidth and the axial bandwidth. Combined with the eigenmode analysis, the asymmetric structure introduced by the traditional tangential perturbation method is replaced by the reasonable filling of two liquid media, dimethyl silicone oil and ethyl acetate, to realize the separation of a pair of equal-amplitude orthogonal in-phase simplex modes into equal-amplitude orthogonal eigenmodes with a difference in phase of 90˚ to achieve the circularly-polarized characteristic (AR < 3 dB), and the switching of the filling method to achieve the axial ratio of the linearly-polarized (AR = 40 dB). With circular polarization (AR < 3 dB) can be reconstructed. Under the precondition of circular polarization, the reconfigurable resonance frequency is realized by changing the filling ratio of the two liquids, and the frequency tuning range of the axial bandwidth is from 2.22 GHz to 2.53 GHz. Each axial bandwidth is completely covered by the impedance bandwidth and the normal gain within the axial bandwidth can reach up to more than 6 dB, which can avoid the extra power caused by the traditional solid state antenna adopting PIN diode, varactor diode, and MEMS to realize the reconfigurable resonance.