用FDTD和物理光学混合法分析毫米波抛物面天线

抛物面天线通常的分析方法是几何光学法和物理光学法,对于电大尺寸的抛物面天线这两种方法都可以得到较好的结果,对于电小尺寸馈源的抛物面天线,馈源方向图不仅取决于辐射器本身的辐射特性,其馈电结构对馈源方向图也有较大的影响,在此情况下,用上述方法得到的结果与实验结果之间有较大的误差.利用FDTD可以把整个馈电结构纳入计算域中,得到辐射器完整的近区场,由等效原理可求出抛物面上电流分布,从而用物理光学方法计算抛物面天线远区场.本文用这种混合方法分析计算了毫米波波导裂缝作为辐射器的抛物面天线,计算结果和测试结果相当吻合,证明了方法的有效性.

Analysis of Paraboloidal Reflector Antenna UsingFDTD Method and Physical Optics

In general,the analysis methods of paraboloidal reflector antenna use geometrical-optics and physical-optics.The preferable numerical results will be obtained by using these two methods for electrically large paraboloidal reflector antenna.For electrically small radiator,the numerical results are not in agreement with experimental results,because the feed pattern are not only determined by feed radiator but also feed structures.In this paper,the finite-difference time-domain method (FDTD) is used to analyze the feed of paraboloidal reflector antenna,and because the computing areas include all the feed structure,we can obtain the precise near fields of the feed.The currents on the paraboloidal reflector can be calculated by using equivalence principle,and then we can calculate far fields of paraboloidal reflector antenna using physical optics.Using this hybrid method,the millimeter wave paraboloidal reflector antenna with waveguide slot feed is analyzed in this paper.Numerical results are compared with the experimental results,and the comparison shows excellent agreement over a wide angle.