FDTD method coupled with FFT: a generalization to open cylindricaldevices

The extension of a numerical method, based on an FDTD algorithm coupled with FFT, is presented. It can be widely applied to the analysis of axially symmetric passive microwave devices. By incorporating the proper radiation conditions in the algorithm, its capacity to deal with the study of open systems is shown; this allows the determination of its quality factor, as well as the resonant frequency and the spatial distribution of the modes. On the other hand, the proper performance of the technique has been verified (stability of the algorithm, accuracy of results) for modes of high angular dependence