Accuracy of Parabolic Equation Method for Modeling LF Electromagnetic Wave Propagation

Abstract

Abstract-The parabolic equation (PE) method, based on the split-step Fourier transform (SSFT) algorithm, has been used to model low-frequency (LF) electromagnetic (EM) wave propagation owing to its efficiency. However, the PE method is derived under the paraxial approximation so that its accuracy is guaranteed only for limited propagation angles from the paraxial direction. Most importantly, the PE method models only one-way forward EM propagation and neglects the backward one, which may become significant in the presence of steep terrain. Therefore, it is essential to properly estimate the accuracy of both narrow-angle (NA) PE (NAPE) and wide-angle (WA) PE (WAPE) methods for LF EM wave propagation prediction over irregular terrain. Since the finite-difference time-domain (FDTD) method has been proven to be the most precise method, in this paper, both the NAPE and WAPE methods are calibrated against finitedifference time-domain (FDTD) method over various paths.