A Dual-band Flexible Wearable Antenna Loaded with an Artificial Magnetic Conductor
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摘要: 该文研究了一种加载人工磁导体(AMC)的双频柔性可穿戴天线,天线的谐振频率为3.5 GHz和5.8 GHz。天线由双频单极子天线和4×4阵列的双频人工磁导体构成,均采用柔性材料作为介质基板。天线尺寸为0.70$ {\lambda _0} $×0.70$ {\lambda _0} $×0.05$ {\lambda _0} $($ {\lambda _0} $为3.5 GHz时的自由空间波长)。人工磁导体的介质基板为3层结构,增加了相位响应,使用双环开槽结构延长电流路径长度,实现了双频的宽带同相位反射。人工磁导体的引入有效降低天线的背向辐射,从而降低比吸收率(SAR),同时提高天线的增益。仿真结果表明,该天线性能受结构变形和人体载荷的影响较小。在工作频段内天线的阻抗带宽分别为7.5%和4.0%;峰值增益分别为7.86 dBi和8.06 dBi。在3.5 GHz和5.8 GHz的比吸收率分别为0.2 W/kg和0.06 W/kg,均小于美国联邦通信委员会标准。为了验证仿真结果,对天线进行加工测试,实测与仿真结果基本一致。实验结果表明,加载人工磁导体的天线具有良好的鲁棒性和增益以及较低的比吸收率,适用于可穿戴无线通信系统。Abstract: A dual-band flexible wearable antenna integrated with an Artificial Magnetic Conductor(AMC) is presented. The design operates at 3.5 GHz and 5.8 GHz. The proposed antenna is composed of a dual-band monopole antenna and a dual-band artificial magnetic conductor with a 4×4 array, both of which are printed on flexible materials. The antenna dimensions are 0.70$ {\lambda _0} $×0.70$ {\lambda _0} $×0.05$ {\lambda _0} $($ {\lambda _0} $ is the free space wavelength at 3.5 GHz). The substrate of the artificial magnetic conductor is based on a three-layer structure, which enhances the phase response. The double-ring slotted structure is used to extend the current path length, achieving dual-band broadband in-phase reflection. Introducing an artificial magnetic conductor effectively reduces the back radiation of the antenna, thereby decreasing the Specific Absorption Rate(SAR) and simultaneously increasing the antenna’s gain. Simulation results show that the performance of the antenna is less affected by structural deformation and human body load. The impedance bandwidths of the antennas in the operating frequency range are 7.5% and 4.0%, and the peak gains are 7.86 dBi and 8.06 dBi. The specific absorption rates at 3.5 GHz and 5.8 GHz are 0.2 W/kg and 0.06 W/kg, respectively. Both values are well below the FCC SAR limits. The antenna was processed and tested to validate the modeling results. The experimental results show that the antenna, loaded with an artificial magnetic conductor, exhibits a low specific absorption rate, strong robustness, and high gain, rendering it suitable for wearable wireless communication systems.
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表 1 单元结构参数(mm)
p L1 L2 L3 W1 W2 h1 h2 15 8.0 13.3 11.8 4.5 9.5 0.2 2.0 表 2 天线结构参数(mm)
wp lp h1 lg rd1 rd2 rd3 rh1 rh2 rh3 rh4 23.0 29.8 0.2 8.6 19.6 7.3 6.5 16.2 3.0 5.0 2.1 rh5 dsd dsh wg wf p L1 L2 L3 W1 W2 2.8 0.3 2.2 9.5 3.0 15.0 7.8 14.1 10.2 4.6 9.2 表 3 人体组织介电常数和厚度
组织 3.5 GHz 5.8 GHz 厚度(mm) $ {\varepsilon _{\mathrm{r}}} $ σ(S/m) $ {\varepsilon _{\mathrm{r}}} $ σ(S/m) 皮肤 37.01 2.02 35.11 3.71 1 脂肪 5.17 0.16 4.95 0.29 5 肌肉 51.44 2.56 48.48 4.96 20 表 4 本文设计与其他文献的对比
文献 尺寸(mm×mm×mm) 频率(GHz) 带宽(%) SAR(W/kg) 峰值增益(dBi) [11] 55.79×52.25×4.5 2.45/3.65 15.7/2.3 0.651/0.369 4.25/7.35 [12] 41×44×1.52 2.40/5.80 3.8/5.2 0.995/0.127 3.74/5.13 [13] 58×54×0.4 2.45/5.80 2.8/3.1 0.300/0.400 3.00/5.30 [14] 136×136×6 2.50/5.20 0.95/1.09 0.332/0.234 8.08/8.74 本文 60×60×4.6 3.50/5.80 7.5/4.0 0.200/0.060 7.86/8.06 -
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