An efficient PSTD algorithm in cylindrical coordinates

The finite-difference time-domain (FDTD) method has been enjoying its widespread applications in the simulations of transient electromagnetic wave propagation and scattering. However, as the the problem size increases, so does the required number of unknowns per wavelength. In cylindrical coordinates, the conventional FDTD method encounters yet two more difficulties: (i) the requirement for a very small /spl Delta/t because of the high concentration of cells near the z axis, and (ii) the singularity at the cylindrical axis. Although various remedies have been proposed, the treatment is not straightforward, and requires extra manipulations and computation time. We propose a pseudospectral time-domain (PSTD) method for 3-D cylindrical and 2-D polar coordinates which will overcome these difficulties and significantly increase the efficiency.