Electromagnetic analysis of axi-symmetric structures

Various types of antennas and transmission media for electromagnetic waves (coax cable, waveguides, etc.) exhibit symmetry around an axis of rotation and hence called bodies of revolution. By analytically extracting the known periodic behavior of the fields in the azimuth, the fields everywhere may be found by solving Maxwell's equations in a single two dimension plane. This body of revolution (BOR) approach has been used in the past with other numerical techniques for solving electromagnetic problems. Although the use of BOR approach with the finite difference time domain (FDTD) technique has already been reported, this paper presents an advanced integration of the FDTD-BOR with the perfectly matched layer absorbing boundary condition. This implementation significantly reduces the undesired reflection of outgoing waves due to the mesh truncation for a wide range of frequencies. Good agreement with published computed and measured data are obtained with the developed FDTD-BOR-PML technique for dielectric resonators and microstrip antennas. The developed algorithm is used for the analysis and design of new types of axi-symmetric antennas for personal wireless communications.