| In recent years, research of high frequency modeling method of electromagnetic scattering of anisotropic coating target becomes a local hot topic, which appled in research of electromagnetic scattering of military target, the expected military application benefit include hiding of radar target(RCS reduction), radar object re-identification and so on, some relevant modeling researches have important theoretical significance and the pratical application value.For electromagnetic scattering problem of anisotropic target, this paper studies from three aspects, first of all on the basis of the early study of electromagnetic scattering modeling method of anisotropic coating target in Wuhan University electromagnetic engineering laboratory, simulations and characteristic analysis has been done for anisotropic coating typical target and missile target, and a lot of results with reference value are acquired. Second, meticulous researches have been done in RCS reduction of anisotropic coating target, include RCS optimization of anisotropic impedance coating target, and the contrast between anisotropic result and isotropic result. Finally, this paper tries to generalize the physical optics (PO) modeling method of anisotropic material coating target to the situation of dipole (point source) excitation, rigorous solution of anisotropic coating (infinite large) plate under point source excitation is obtained, then asymptotic solution (PO solution) is obtained using saddle point method in the spectral domain. Kinds of scattering mechanism in solve process has been analyzed particularly, different physical picture has been builded and computation examples of anisotropic material coating typical target under point source excitation have been given.The main content of this paper includes the following parts:1) Several calculations of scattering characteristic analysis show the ability of anisotropic coating material that can change the electromagnetic scattering character which is different from isotropic coating. Reserches also reveal that, ? no matter the loss coating situation or weak loss coating situation, scattering difference between two orthogonal polarization of anisotropic coating target is very large, and results in two orthogonal view plane appear complementarity; ? Relative to isotropic coating situation, anisotropic coating typical target not only has ability of RCS reduction but also can enhance the RCS; ? The frequency characteristic of anisotropic coating typical target is very peculiar, in some material coating situation, scattering characteristic of shock period when frequency changes will be changed, and shock period will reduce even disappear.2) Take anisotropic material coating flate for object of study,optimization of RCS has been studied using genetic algorithm (GA), which include taking step to optimize the anisotropic parameter, and taking partition to coat with anisotropic material. Results reveal that several partitions anisotropic coating plate obtain better RCS reduction compared with non-partition anisotropic coating plate. Results conform to the expectation.3) PO solution of electromagnetic scattering of anisotropic coating target under point source excitation has been derived, which will be the basis of research of near field high frequency solution of anistropic coating target under point source excitation. For scattering model of anisotropic coating infinite plate under dipole excitation, first of all, rigorous solution of the problem in the spectral domain has been derived, which include the total field and field inside coating media and out of coating media represented in spectral integral; Then every spectral integral has been computed using sadlle point method, and which has property of ray field can derived represented by PO; Using the physical meaning of saddle point in this problem, scattered field transmitting in and out of anisotropic layer is analized and physical picture of transmitting and scattering of ray wave field is builded. |
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