Wong Hang, Lin Wei, Huitema Laure, Arnaud Eric
IEEE Trans Biomed Circuits Syst. 2017 Jun;11(3):652-660. doi: 10.1109/TBCAS.2016.2636872. Epub 2017 May 19.
This paper presents a multi-polarization reconfigurable antenna with four dipole radiators for biomedical applications in body-centric wireless communication system (BWCS). The proposed multi-dipole antenna with switchable 0°, +45°, 90° and -45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS. To realize this reconfigurable feature for the first time among all the reported antenna designs, we assembled four dipoles together with 45° rotated sequential arrangements. These dipoles are excited by the same feeding source provided by a ground tapered Balun. A metallic reflector is placed below the dipoles to generate a broadside radiation. By introducing eight PIN diodes as RF switches between the excitation source and the four dipoles, we can control a specific dipole to operate. As the results, 0°, +45°, 90° and -45° linear polarizations can be switched correspondingly to different operating dipoles. Experimental results agree with the simulation and show that the proposed antenna well works in all polarization modes with desirable electrical characteristics. The antenna has a wide impedance bandwidth of 34% from 2.2 to 3.1 GHz (for the reflection coefficient ≤ -10 dB) and exhibits a stable cardioid-shaped radiation pattern across the operating bandwidth with a peak gain of 5.2 dBi. To validate the effectiveness of the multi-dipole antenna for biomedical applications, we also designed a meandered PIFA as the implantable antenna. Finally, the communication link measurement shows that our proposed antenna is able to minimize the polarization mismatching and maintains the optimal communication link thanks to its polarization reconfigurability.
本文提出了一种用于以人体为中心的无线通信系统（BWCS）生物医学应用的具有四个偶极辐射器的多极化可重构天线。所提出的具有可切换0°、+45°、90°和 -45°线性极化的多偶极天线能够克服BWCS等复杂无线信道中的极化失配和多径失真。为了在所有已报道的天线设计中首次实现这种可重构特性，我们将四个偶极以45°旋转顺序排列组装在一起。这些偶极由接地渐变巴伦提供的相同馈电源激励。在偶极下方放置一个金属反射器以产生宽边辐射。通过在激励源和四个偶极之间引入八个PIN二极管作为射频开关，我们可以控制特定的偶极工作。结果，0°、+45°、90°和 -45°线性极化可以相应地切换到不同的工作偶极。实验结果与仿真结果一致，表明所提出的天线在所有极化模式下均能良好工作，具有理想的电气特性。该天线在2.2至3.1 GHz范围内具有34%的宽阻抗带宽（反射系数≤ -10 dB），并且在整个工作带宽内呈现出稳定的心形辐射方向图，峰值增益为5.2 dBi。为了验证多偶极天线在生物医学应用中的有效性，我们还设计了一种曲折型PIFA作为植入式天线。最后，通信链路测量表明，由于其极化可重构性，我们提出的天线能够最小化极化失配并保持最佳通信链路。
