A HIGH-ACCURACY FDTD ALGORITHM TO SOLVE MICROWAVE PROPAGATION AND SCATTERING PROBLEMS ON A COARSE GRID

If the spatial variation of electric permittivity and magnetic permeab ility is ''small'' Maxwell's equations can be approximated by the scal ar wave equation in each field component, We introduce a new high-accu racy second order finite-difference time-domain (FDTD) algorithm to so lve the scalar wave equation on a coarse grid with a solution error le ss than 10(-4) that of the conventional one. The computational load at each grid point is greater, but it is more than offset by a large red uction in the number of grid points needed, as well as by a reduction in the number of iterations. Also boundaries can be more accurately ch aracterized at the subgrid level. Although optimum performance is achi eved at a fixed frequency, the accuracy is still much higher than that of a conventional FDTD algorithm over ''moderate'' bandwidths.