This paper presents a study on the inverse electromagnetic scattering problem of three-dimensional (3D) objects embedded in half-space media. To address this problem, the subspace-based variational Born iterative method (S-VBIM) is used, which combines the subspace optimization method (SOM) and the VBIM. The key idea of S-VBIM is to exploit the deterministic subspace of the variational-induced current, while ignoring its ambiguous part, to update the total field at each iteration step. This approach ensures that the method has fast convergence and high reconstruction accuracy. We demonstrate the application of the S-VBIM method to the challenging problem of imaging buried 3D objects that are consistent with real-world scenarios. To assess the feasibility and effectiveness of S-VBIM, we provide several numerical examples, including imaging of embedded 3D objects with arbitrary shapes and numbers. Our results demonstrate that the S-VBIM provides a promising approach for reconstructing complex subsurface targets in three-dimensional settings, even under significant measurement noise.
To address the challenge of high-altitude electromagnetic pulse (HEMP) infiltration into equipment cavities, which threatens internal electronics, conventional simulation methods like the finite integral technique (FIT) often suffer from high computational cost and low efficiency. This study proposes a novel approximate method based on the superposition of decaying oscillating plane waves (DOPW-S) to efficiently simulate the intra-cavity pulsed electromagnetic environment. Simulation results demonstrate that the DOPW-S method produces waveform characteristics similar to FIT and shows good agreement in the cumulative probability distribution of electric field peaks, verifying its feasibility for simulating complex cavity fields. Furthermore, the DOPW-S method reduces computation time by 95.93% compared to FIT.
