Aiming at the high efficiency of composite electromagnetic scattering analysis and radar target detection and recognition utilizing high-range resolution profile (HRRP) characteristics and high-resolution synthetic aperture radar (SAR) images, a near-field modified iterative physical optics and facet-based two-scale model for analysis of composite electromagnetic scattering from multiple targets above rough surface have been presented. In this method, the coupling scattering of multiple targets is calculated by near-field iterative physical optics and the far-field scattering is calculated by the physical optics method. For the evaluation of the scattering of an electrically large sea surface, a slope cutoff probability distribution function is introduced in the two-scale model. Moreover, a fast imaging method is introduced based on the proposed hybrid electromagnetic scattering method. The numerical results show the effectiveness of the proposed method, which can generate backscattering data accurately and obtain high-resolution SAR images. It is concluded that the proposed method has the advantages of accurate computation and good recognition performance.

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Aiming at improving the accuracy and efficiency of scattering information from multiple targets in near-field regions, this paper proposes a near-field iterative physical optics (IPO) method based on a modified near-field Green’s function for the composite electromagnetic scattering analysis of multiple hybrid dielectric and conductor targets. According to the electric field and magnetic field integral equation, the electric and magnetic current were updated utilizing the Jacobi iteration method. Then, by introducing an expansion center lying in the neighborhood of the source point, Green’s function was modified for near-field scattering between multiple hybrid dielectric and conductor targets. To accelerate the implementation of the procedure, the multilevel fast multipole method, the fast far-field approximation, and parallel multicore programming were introduced. Numerical results indicate that there is good agreement between the results calculated by the near-field IPO method and MLFMM solver in commercial software FEKO while significantly reducing the computational burden. To fully exploit the scattering information, the high resolution range profiles (HRRP) of different targets under different conditions were analyzed, which can be further applied for automatic target detection and recognition.

The composite electromagnetic (EM) scattering characteristics from a target above a canyon/valley environment are significant. Aiming to acquire the composite EM scattering efficiently and accurately, the framework of the canyon/valley environment modeling method and modified shooting and bouncing rays (SBR) hybrid with facet-based small slope approximation (FBSSA) algorithm is investigated. Firstly, the canyon/valley environment containing two slopes and a bottom modeling method is proposed. Then, considering the environment’s roughness, the modified SBR algorithm introduced by the high-order reflection model is proposed. Combined with the FBSSA, the modified SBR-FBSSA algorithm is an efficient and accurate method to predict composite EM scattering based on numerical verification. Finally, the effects of different surface types, roughness, slope angles, and incident-pitch and azimuth angles on the composite EM scattering characteristics are further analyzed. The work presented in this article provides a way to study the composite EM scattering from a target above the canyon/valley environment. Meanwhile, the complex scattering mechanism is revealed, and some valuable conclusions are put forward based on the physical phenomena.

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