On the Solution of a Class of Large Body Problems with Full or Partial Circular Symmetry by Using the Finite-Difference Time-Domain (FDTD) Method

This paper presents an efficient method to accurately solve large body scattering problems with partial circular sym­ metry. The method effectively reduces the computational domain from three to two dimensions by using the reciprocity theorem. It does so by dividing the problem into two parts: a larger 3-D region with circular symmetry, and a smaller 2-D region without circular symmetry. An finite-difference time-domain (FDTD) algorithm is used to analyze the circularly symmetric 3-D case, while a method of moments (MoM) code is employed for the nonsymmetric part of the structure. The results of these simulations are combined via the reciprocity theorem to yield the radiation pattern of the composite system. The advantage of this method is that it achieves significant savings in computer storage and run time in performing an equiv­ alent 2-D as opposed to a full 3-D FDTD simulation. In addition to enhancing computational efficiency, the FDTD algorithm used in this paper also features one improvement over conventional FDTD methods: a conformal approach for improved accuracy in mod­ eling curved dielectric and conductive surfaces. The accuracy of the method is validated via a comparison of simulated and mea­ sured results.