Rotationally symmetric (RS)-LOD-FDTD with CPML for analysing resonant structures

摘要

Structures with rotational symmetry (RS) are commonly encountered in many wireless systems that involve antennas and microwave filters. Such rotationally symmetric structures have body of revolution (BOR) symmetry which allows one to analytically extract the known azimuthal behaviour of the fields around the axis of symmetry, and to project the original three-dimensional problem to a numerically solvable two-dimensional plan, reducing the computationally burden substantially in the process. The rotationally symmetric resonant structures have been analysed using various analytical and numerical methods of electromagnetics such as the mode matching method, integral equation technique, the finite element method, and the finite difference time domain method [1]-[2]. The rotationally symmetric finite-difference time domain (RS-FDTD) method has also been used effectively for treating electromagnetic problems in time domain, involving structures with circular symmetry [2]. However, RS-FDTD suffers from Courant-Friedrich-Lewy (CFL) stability constraint and as a result, finer grid sizes and smaller time steps are required to retain the stability which will cause significant increase in computational time.