A nonorthogonally-oriented higher-order FDTD technique for 3-D waveguide and antenna structures on curvilinear grids

A generalized higher-order FDTD technique for the accurate modeling of complex waveguide and antenna configurations in 3-D nonorthogonal curvilinear coordinates, is presented in this paper. The novel methodology which introduces conventional and nonstandard differencing concepts, embodies an efficient treatment of the div-curl problem on an unstructured lattice and develops enhanced perfectly matched layer absorbers for the truncation of unbounded domains. Moreover, a progressively mesh expanding algorithm leads to a serious decrease of the overall mesh. In the temporal variable, the four-stage Runge-Kutta integrator is also invoked, whereas the wider spatial increments are effectively limited by a new class of self-adaptive compact operators. Numerical verification illustrates that the proposed technique offers a significant mitigation of dispersion errors, yields precise values for the S-parameters and performs promising radiation pattern computations for various kinds of contemporary antennas.