UTD Solution For The Diffraction By An Anisotropic Impedance Wedge With Arbitrary Exterior Wedge Angle At Arbitrary Skew Incidence

The research of the diffraction from wedge with anisotropic impedance has great contribution to radar detection, electromagnetic wave propagation and design of high-frequency antenna, etc. However the high-frequency techniques can not solve the general problems, such as arbitrary skew incidence case and arbitrary exterior wedge angle case, as well as the numerical approaches. Considering the time-consuming is very important in engineering applications, in this paper, a numerical matching method which is based on the framework of the uniform geometrical theory of diffraction(UTD) is developed to build the spectral functions for computing the diffraction field by anisotropic impedance wedge at an arbitrary skew incidence. For efficiency consideration, the spectral functions of a few number of incident angles are derived with the proposed numerical matching method and set as the sampled data set. On the basis of these sampled incidence cases, the numerical interpolation and the asymptotic waveform evaluation technique are employed to deduce the spectral function at any other skew incidence in the whole angle space. Then the satisfactory UTD solutions are obtained over the whole angle space. The contents are in the four aspects below:1. The surface waves and the diffraction of the surface waves excited by an anisotropic impedance wedge at oblique incidence are obtained by using perturbative approach for making the UTD solutions completely. According to the residue theorem, the contributions of the residue of spectral function's image poles correspond to the surface wave field. Then by applying the Van der Waerden method, the diffraction of the surface wave field is given.2. A numerical matching method is proposed to obtain the spectral functions of arbitrary skew incidence angles in this paper. A few number of skew incident angles are chosen as the sampled points, the numerical matching is applied on the wedge faces for every sampled incidence case. The restriction of the boundary conditions on the wedge faces are enhanced during the solution and then an appropriate expression of the spectral function could be worked out. Then the the numerical interpolation and AWE technique are applied to get the spectral function at an arbitrary skew incidence angle. Finally the UTD solutions of the anisotropic impedance wedge scattering are obtained over the whole skew incident angle space.3. By revising the Maliuzhinets function in the skew incidence case, the satisfactory Maliuzhinets function is obtained when the skew incidence angle is large deviations from normal incidence. Then the UTD solutions of the anisotropic impedance wedge at arbitrary skew incidence can be obtained by appling the numerical matching method based on the normal incidence or based on grazing to the edge incidence only.4. The numerical matching method is also used to obtain the concise form of the Maliuzhinets special functions of arbitrary exterior wedge angle case. Then the spectral functions of arbitrary exterior wedge angle case and arbitrary skew incidence angle can be obtained by applying the numerical matching method.