WBPAT for FDTD simulation of microwave devices with homogeneous waveport

Abstract

Accurate power-to-amplitude transformation (PAT) has been proposed for the continuous wave (CW, i.e. sinusoidal wave or multi-carrier) to stimulate the quantitative electromagnetic fields under specified average input power with the finite-difference time-domain (FDTD) method for simulation of microwave devices. In this study, the authors propose wideband PAT (WBPAT), by which quantitative amplitude and phase of electromagnetic fields at desired frequencies can be accurately extracted for microwave devices with homogeneous waveport under specified average input power when the excitation waveform of specified waveguide mode is wideband impulse signal. In the proposed WBPAT, the information of incident wave for normalisation is needed, which is investigated and discussed. Furthermore, a post-processing procedure called as the mode-impedance-modified normalisation is proposed to consider the frequency dependence of mode impedance, in which the mode impedance in wideband is obtained by FDTD simulation, per se. The average input power is defined for each frequency within the frequency range. As a result, accurate amplitude and phase, which is equivalent to that by frequency-domain methods or TD methods with the excitation of CW after steady state, can be extracted. Several numerical examples show the validity of the proposed method.