Modeling of Lossy Curved Surfaces in 3-D FIT/FDTD Techniques

A conformal first-order or Leontovic surface-impedance boundary condition (SIBC) for the modeling of lossy curved surfaces in a Cartesian grid is presented for the finite-integration technique (FIT). Equivalently, the model can be derived using the contour-path formulation of the finite-difference time domain (FDTD) method. The SIBC is based on a lumped-element representation of the impedance combined with a conformal modeling scheme. The validity of the proposed model is evaluated by investigating the quality factors of rectangular, cylindrical and spherical cavity resonators. The convergence rate of the conformal SIBC model is shown to be of second order