A Modified Nonorthogonal FDTD Algorithm for the Analysis of 3D Inhomogenous Resonant Cavities

A modified FDTD model is investigated to analyse arbitrary electromagnetic structures with curved material boundaries using a Cartesian co-ordinate system. Modifications based on a nonorthogonal FDTD method are presented which are more efficient than general nonorthogonal FDTD schemes in terms of computer resources such as memory and CPU time. Moreover, some existing FDTD algorithms based on the Cartesian coordinate system can be immediately incorporated into this modified model, such as Absorbing Boundary Condition(ABC) and near-far field transformation. The effectiveness and accuracy of this model for the analysis of complex structures is demonstrated by calculating the resonant frequencies of some 3D cylindrical cavity resonators with different shapes of dielectric fillings.