Study on Analysis of Electromagnetic Phenomena Using Time Domain Technique Based on Maxwell's Equation

本研究阐明了天线等辐射元件的电磁现象。利用时域技术，提出了满足天线尺寸条件和性能要求的天线元件设计方法。结果表明，该方法对天线特性的评估是有效的。一种被认为适合许多应用的腔背槽天线是我们在这项研究中的目标。我们得到了如下所示的新结果。提出了一种基于时域有限差分法的腔背缝隙天线输入特性和辐射方向图评估方法。我们还提出了用时间窗和同轴模型估计输入特性的方法，并证明了其有效性。此外，我们给出了绝对增益和辐射方向图的解析方法。研究了一种满足SPS2000太阳能卫星尺寸和天线性能要求的天线单元。它具有相当简单的进料器，位于腔体的底平面上，以低轮廓的腔体几何形状实现了所需的特性。所研究的馈线是一个短探头和一个倒f元件。天线单元间的相互耦合和波束导向性能的估计，以及低轮廓腔背槽天线的研制，是今后研究的重点。

In this study we clarify electromagnetic phenomena of radiating elements such as an antenna. We also develop the design method of antenna elements that satisfies conditions of the antenna dimension and realizes desired performance using the time domain technique. Moreover we show that the method is effective to evaluate the antenna characteristics. A cavity-backed slot antenna that is considered as an element suitable for a lot of applications is our target in this study. We obtained the new results shown below.1.We developed an evaluation method of input characteristics and radiation patterns of the cavitybacked slot antenna using the finite-difference time-domain method. Also we propose to apply the time windowing and the coaxial model for the estimation of input characteristics, and show its effectiveness. Furthermore we show the analytic method of absolute gains and radiation patterns.2.We investigate an antenna element that satisfies the dimension and antenna performance required for the solar power satellite SPS2000. It has the quite simple feeder located in the bottom plane of the cavity and realizes the desired characteristics with the low-profile cavity geometry. The investigated feeders are a shorted probe and an inverted-F element.The subjects that should be taken into account in future studies are the estimation of mutual coupling among antenna elements and the performance of beam steering, and the development of the low-profile cavity-backed slot antenna.