絕緣偶極天線在損耗性介質中之高速演算場量方法

Abstract

微波熱療在醫學上已廣受重視、應用，分析絕緣偶極天線的近場特性 可用以設計和評估一個微波熱療系統。本篇論文提出一個快速的演算方法 用來決定植入式絕緣偶極天線在均勻損耗性介質中的特性，其間是以細線 近似的電流分佈方式來加以分析，在此方式下，電磁波從偶極天線軸上的 微小電流源直接輻射進周圍的損耗介質中，在電磁場積分時，應用平移對 稱法可較 King-Casey 的積分法節省相當大的計算時間。此外，利用場量 主要來自天線上與觀測點靠近的部份，加上一收斂標準可再省下三倍的計 算時間。在這演算方法下，理論和實驗有相當一致的結果。 The application of microwave hyperthermia in medical treatment is being emphasized. Analysis of the near field characteristics of an insulated dipole antenna (IDA) is instrumental in the design and evaluation of the heating performance of an interstitial microwave hyperthermia system. A fast algorithm for determining the characteristics of an IDA embedded in a homogeneous dissipative medium is described in this thesis. A thin-wire approximation type of analysis is followed here. In this case, radiation is considered to originate from a filamentary current flowing along the axis of the dipole that is surrounded immediately by the ambient dissipative medium. The translational symmetry inherent in the resultant radiation integrals is then used to yield accurate results and to speed up the computation in much less CPU time than the traditional King-Casey approach [1] [2]. Additionally, a 3-fold improvement in CPU time is achieved by incorporating a convergence criterion such that only the significant contributions from a portion of the antenna are included while computing the field at a given location. Agreements between theoretical and experimental results are demonstrated.