Generalised higher-order FDTD-PML algorithm for enhanced analysis of 3D waveguiding EMC structures in curvilinear coordinates

A 3D higher-order FDTD methodology for the efficient solution of complicated waveguide EMC problems in non-orthogonal coordinate systems is presented. Introducing a new topological classification of accurate non-standard schemes, the algorithm develops a consistent covariant/contravariant formulation which fulfils the proper continuity conditions and eliminates every critical lattice dispersion error. Moreover, the wider spatial stencils near arbitrarily-curved boundaries are successfully manipulated via self-adaptive compact operators, whereas temporal advancement is performed by a generalised leapfrog approach. Conversely, for the termination of infinite waveguide ends, the proposed higher-order concepts are applied to the systematic construction of reflectionless curvilinear PMLs that can be imposed very close to structural discontinuities. Due to their optimal arrangement and a flexible pulsed-modulated excitation process, these absorbers accomplish substantial attenuation rates, even for laborious domains or broadband frequency spectra. Numerical results addressing diverse multiport waveguides with inclined slots and irises reveal that the novel strategy exhibits superior accuracy and significant savings in computer resources