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.

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.

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.