Realization of EM-wave absorbers for improving EM field environment between ETC lane

近年来，无线LAN系统已经越来越广泛地应用于办公楼以及住宅中。另一方面，由于担心电磁（EM）波的泄漏对安全性的风险或者由于用于通信的EM波的多径和/或衰落而降低无线通信的质量，用于无线LAN的通信环境已经成为讨论的主题。在这样的背景下，有最好的方法是将EM波吸收器应用到房间的某一部分，以防止multiplex.In本研究中，在无线LAN通信的房间中的传播的改善进行了实验和分析，通过开发的三层型吸波器由普通的建筑材料。结果表明，在2.4-2.5GHz频段，平均吸收性能为10.4dB，平均时延扩展为反射良好环境的一半。此外，还利用射线追踪法进行了模拟，计算出的归一化延迟扩展的位置数与实验结果基本一致。此外，还从理论和实验两方面研究了在无线局域网（IEEE 802.11a，b/g）中增加隔片式电磁波吸收器的电磁波吸收功能。计算结果表明，在2.45GHz和5.2GHz处，垂直入射的吸收率分别达到20 dB以上。根据计算结果制作了吸波体样品，并在电波暗室中对吸波体的性能进行了测试。在5 °和20 °之间的入射角范围内，对TE、TM和圆偏振波的吸收为15 dB或更高。是通过实验获得的。

In recent years, wireless LAN systems have been increasingly used more widely in office buildings as well as houses. On the other hand, the communication environment for wireless LAN has become a subject of discussion, due to concerns about risks to security by leakage of electromagnetic (EM) waves or reduction of the quality for wireless communication by multipath and/or fading of the EM wave for communication. In such a background, there is the best way to apply EM-wave absorbers to a certain portion of the room in order to prevent multipath.In this study, the improvement of propagation in the room for wireless LAN communication is investigated experimentally and analytically by making the developed three-layer-type wave absorber consist of common building materials. As a result, the average absorption performance is found to be 10.4dB (2.4-2.5GHz) that makes the average delay spread one-half of that of the well-reflected environment. Moreover, simulation using the ray-tracing method is also performed in this room and the results for number of positions the normalized delay spread calculated by the simulation are similar to those obtained from the experiment.Furthermore, EM wave absorber with partition type add the function of EM wave absorption for wireless LAN (IEEE 802.11a,b/g) is also examined theoretically and experimentally. As a result, the absorption of 20dB or more for vertical incident is obtained at 2.45GHz and 5.2GHz in calculation, respectively. The wave absorber sample is fabricated based on the calculated results and the performance of this absorber is examined in anechoic chamber. The absorption of 15dB or more for TE, TM, and circularly polarized wave at the incident angle ranging between 5 and 20 deg. are obtained experimentally.