中文摘要：

本文给出了一种利用分层介质构造低通滤波器的设计方法．基于阶跃阻抗低通滤波电路设计理论，交替使用高波阻抗和低波阻抗的介质，实现了低通滤波电路的频率响应，并使用时域有限差分法（FDTD）进行数值模拟，验证了滤波电路的频率响应．本文对比了FDTD和隐式FDTD对滤波电路的仿真．隐式FDTD具有较高的效率和精度，适于精细结构的数值模拟计算．这种低通滤波器还可使用同轴线或波导来构造，具有结构简单和尺寸小的优点．随着微波特殊材料技术的发展，这种分层介质滤波器的结构在射频通信、电磁兼容和微波化学等领域具有良好的应用前景．

英文摘要：

A method to design layered dielectric low pass filters is presented. Based on the theory of stepped impedance filters, a filter is built with alternated high and low wave impedance dielectrics. With the finite difference time domain （FDTD） method, the characteristics of the filter are simulated and verified. The conventional FDTD method and implicit FDTD method are compared in one filter example as well. The implicit FDTD method is more accurate and efficient, and owns some advantages over conventional FDTD on simulations of electrically small objects. The proposed filters may be built in coaxial lines or waveguides, and find applications of radio frequency communications, electromagnetic compatibility, and microwave chemistry. The filters have more and more applications with developed microwave metamaterials.