Design of a Wideband L-Shape Fed Microstrip Patch Antenna Backed by Conductor Plane for Medical Body Area Network
Design of a Wideband L-Shape Fed Microstrip Patch Antenna Backed by Conductor Plane for Medical Body Area Network
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DOI：
10.3390/electronics9010021
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发表时间：
2020-01-01
期刊：
影响因子：
2.9
通讯作者：
Fujimoto, Takafumi
中科院分区：
文献类型：
--
作者：
Guan, Chai-Eu;Fujimoto, Takafumi
本文介绍了一种用于医学体域网的小型贴片天线。天线采用邻近耦合方案馈电，以支持在2.45 GHz ISM频段在自由空间和人体上辐射的天线。导体平面放置在天线下方2mm或0.0163 λ（0）（λ（0）是2.45GHz处的自由空间波长）处，以减少对人体的反向辐射。天线与人体之间的距离必须保持在2 mm以上，否则天线的增益会随着天线贴在人体上而降低。引入L形馈线以克服结构紧凑引起的阻抗失配。该天线的耦合间隙和L形馈线的长度进行了优化，以产生宽阻抗带宽的双谐振模式。仿真结果表明，该天线的比吸收率（SAR）的L形馈线比传统的贴片天线直接微带馈线。该天线在中心频率为2.45 GHz处实现了120 MHz（4.89%）的阻抗带宽。在自由空间中，天线的最大侧边增益为6.2dBi，实测值为5.09dBi。实现了宽阻抗带宽和对人体存在不敏感的辐射方向图，满足了基于物联网的可穿戴传感器的要求。
This paper describes a compact patch antenna intended for medical body area network. The antenna is fed using a proximity coupling scheme to support the antenna that radiates in the free space and on the human body at the 2.45 GHz ISM band. The conductor plane is placed 2 mm or 0.0163 lambda(0) (lambda(0) is free space wavelength at 2.45 GHz) below the antenna to reduce backward radiation to the human body. Separation distance must be kept above 2 mm, otherwise, gain of the proposed antenna decreases when antenna is situated on the human body. The L-shape feed line is introduced to overcome impedance mismatch caused by the compact structure. The coupling gap between the proposed antenna and the length of the L-shape feed line are optimized to generate dual resonances mode for wide impedance bandwidth. Simulation results show that specific absorption rate (SAR) of the proposed antenna with L-shape feed line is lower than conventional patch antenna with direct microstrip feed line. The proposed antenna achieves impedance bandwidth of 120 MHz (4.89%) at the center frequency of 2.45 GHz. The maximum gain in the broadside direction is 6.2 dBi in simulation and 5.09 dBi in measurement for antenna in the free space. Wide impedance bandwidth and radiation patterns insensitive to the presence of human body are achieved, which meets the requirement of IoT-based wearable sensor.