To predict the propagation of radio waves in the environment of dielectric ground and dielectric obstacles, a new two-way parabolic equation (2W-PE) method based on the domain decomposition principle and surface impedance boundary conditions (SIBC) is proposed. First, we decompose the obstacle area into different subdomains and derive the SIBC in each subdomain in detail; then, the discrete hybrid Fourier transform (DMFT) in the upper subdomain and finite difference (FD) algorithm in the lower subdomain is used to solve 2W-PE combined with SIBC, respectively. After that, we explain the algorithm steps in the process of calculating the total field, compared with the traditional 2W-PE, and then finally introduce the method of moments (MoM) combined with the enhanced discrete complex image (E-DCIM) method for accuracy verification of the new 2W-PE algorithm. The simulation results show that no matter how the obstacle medium parameters change, the results of 2W-PE method proposed in this paper and MoM are always in good agreement, which proves the accuracy of 2W-PE and its superiority in speed. Therefore, this paper provides a reliable and efficient method for solving the problem of radio wave propagation in the presence of obstacles, especially in the case of low-lossy obstacles.

As a non-iterative linear inverse scattering imaging method, the linear sampling method (LSM) has the merits of easy implementation and high computational efficiency. In this article, based on the LSM and T-matrix method, we propose a fast method to reconstruct the target medium parameters. First, we use the LSM qualitative imaging method to estimate the contour of the target. Then, the preprocessing information of the LSM is applied to the virtual experiment circles in the framework of T-matrix method. In this way, we avoid the inversion of the matrix and only need to solve a series of univariate equations. Numerical simulation results show that the reconstruction accuracy of the proposed method is similar to that of LSM quantitative imaging method, but it has higher calculation accuracy and wider application range. Although the calculation accuracy is not as good as the contrast source inversion (CSI) method, the proposed method has huge advantages in terms of calculation efficiency. INDEX TERMS Electromagnetic inverse scattering, linear sampling method, microwave imaging, Tmatrix, virtual experiments

To study the problem of radio wave propagation in an environment of dielectric ground and obstacles, especially in low-lossy obstacles, to consider the propagation inside the obstacle, a new method is proposed to solve the two-way parabolic equation based on the principle of domain decomposition. First, a mathematical model of parabolic equations for reflection and refraction in an environment with obstacles is established. Then, the area of the obstacle is decomposed into two different subdomains; the discrete mixed Fourier transform is used to calculate the field value in the upper subdomain from the top of the obstacle to the absorption boundary, the finite difference method is used to calculate the field value of the lower subdomain inside the obstacle, and the field strengths and phases of the two subdomains coordinate with the boundary conditions. In the process of calculation, we emphatically consider the multiple reflection and transmission paths inside obstacles to make the algorithm results more accurate. In addition, we verified the stability and convergence of the method. Finally, the simulation results show that the proposed method and the method of moments have good consistency, so the algorithm has the characteristics of strong applicability and fast calculation speed, which provide a novel and reliable method to research the wave propagation problem in a modified environment of obstacles.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

In this paper, an improved T-matrix method is proposed to improve the accuracy for simultaneous reconstruction of dielectric scatterers and perfectly electric conductors (PEC). First, we modify the original T-matrix inversion method and obtain a preliminary reconstruction result. Then treat this result as a priori information, and a new initial iteration value is generated by truncating and assigning values to it. At the same time, genetic algorithm (GA) is used to optimize these truncation and assignment parameters. Finally, the optimization result is used as the initial value of the modified T-matrix method to obtain better reconstruction accuracy. The numerical simulation results under noisy conditions show that the proposed method can more clearly reconstruct the edges of the objects and have higher reconstruction accuracy. INDEX TERMS Electromagnetic inverse scattering, T-matrix, genetic algorithm (GA), microwave imaging, high accuracy

In the usual process of teaching students about the electromagnetic field, students often have difficulty in understanding the propagation process of invisible electromagnetic waves under different medium environments. To facilitate students understanding and learning of related knowledge, in this article, we first derive the process of solving Maxwell’s equation using finite-difference time-domain (FDTD) under different media environments for the designed experimental models to obtain the spatial distribution of the electromagnetic field. After that, we use the MATLAB language to program the FDTD solution method to verify our theoretical analysis based on the simulation results. Based on this, we develop a convenient and quick interactive mobile software tool, aiming to give students a vivid and intuitive demonstration and explanation for the propagation of electromagnetic waves in different media environments.