損失性媒質近傍に置かれたコンプリメンタリスプリットリングフィルタの伝送特性

摘要

In recent years, left-handed materials (LHMs) have been receiving major emphasis and microwave and millimeter-wave system applications have also been studied. Among these LHMs, SRRs/CSRRs are mainly used to realize the compact band pass (or rejection) filters because they show relatively good cutoff characteristics even . with the smaller size of the niters. Human hands affect radio-frequency devices such as built-in antennas when these devices are used by the operator. In this paper, transmission characteristics of microstrip line niters with CSRR placed in the vicinity of lossy medium were simulated with the FDTD method. The calculated results demonstrate that the resonant frequency of the CSRRs was shifted to lower frequency and the filter characteristic was deteriorated. To improve the total radiation efficiency of the antenna system covered by human hand, parallel feeding model with two radiating elements combined with CSRR filter configuration has been proposed and studied. In conclusion, the radiation efficiency of the total antenna system was improved by approximately 26 percent even when one of the radiating elements is covered with human hand because the input power to the covered radiating element is reduced.%近年，左手系媒質の研究が盛んに行われており，マイクロ波及びミリ波技術への応用が検討されている.左手系媒質の一種であるSRR及びCSRRは，波長短縮率が大きく遮断特性があることから，小形フィルタの作成に利用されている．一方で，無線端末を使用する際アンテナを含めた無線高周波デバイスに人体が近接する場合，人体がアンテナ特性及び無線高周波デバイス特性に影響を与えることが報告されている.そこで本論文では，MSLに装荷されたCSRRを用いた帯域通過フィルタの損失性媒質近傍における通過特性をFDTD法により計算した.計算結果より，CSRRと損失性媒質間の距離が2．0mm以下では，フィルタの動作周波数が低域に推移し，フィルタ特性が劣化する事を確認した．さらに，二つのアンテナ素子に並列給電する構造において，CSRR帯域通過フィルタを給電線終に装荷したモデルを提案した．CSRRを用いた本方式により，52％であった放射効率が78％に上昇する事を確認したので報告する．