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Plane wave scattering by an infinite, three-dimensional wedge whose faces are characterized by periodic anisotropic impedances is investigated. An improved hybrid of the moment method (MM) and the physical optics (PO) is proposed to calculate the equivalent electric current on the wedge surface. As for the infinite periodic wedge surface, a periodic representation of the scattering surface is used to prevent nonphysical edge effects in the scattering evaluation. The surface of the wedge is split into an MM region and a PO region. In the implementation of MM, the evaluation of the interaction matrix elements in the MM region is simplified by deriving six universal series. Moreover, the PO-current is modified by a diffracted current to improve its accuracy. The accuracy and effectiveness of the proposed approach is validated and demonstrated by using series solution, the method in [T. B. A. Senior, “Solution of a class of impedance wedge problem for skew incident,” Radio Sci., vol. 21, no. 2, pp. 185–191, 1986], and the two-dimensional improved MM-PO approach under several canonical two-dimensional wedge cases. At last, the proposed approach is applied to analyze the scattering from the wedges with periodic anisotropic impedance faces, and the numerical results are presented. [ABSTRACT FROM PUBLISHER]

This paper presents a novel and original approach for the evaluation of electromagnetic (EM) scattering from electrically large and complex target coated with uniaxial electric anisotropic medium (UEAM) layer. The evaluation includes two indispensable aspects, the geometry modeling of the target and the determination of the surface currents. Once the equivalent surface currents (ESCs) induced on the outer surface of the coated target are determined, the scattered field could be calculated by the corresponding radiation integrals. First, the outer surface of the arbitrarily shaped target is discretized using flat triangle facets. Second, the ESCs on any facet are deduced from the surface fields, which involve a complicated coupling of type I and type II waves existing in the UEAM. Thus, the determination of the surface fields and the ESCs on the surface of the target with large radius of curvature is the crux of the whole evaluation. By making the tangent plane approximation, used in the physical optics (PO) method, any discretized flat facet could be approximated as an infinite PEC plate coated with a homogenous UEAM layer. Thereafter, the scattering from the infinite coated plate is asymptotically calculated by using the proposed spectral domain method combined with saddle point evaluation (SDM-SPE). Ultimately, comparisons of the proposed asymptotic solution with the reference solutions calculated numerically confirm the validity and efficiency of the proposed SDM-SPE. Numerical results of several canonical and complex targets coated with UEAM layer are given by the proposed approach for the first time. [ABSTRACT FROM PUBLISHER]

Adopting a method of moments/physical optics (MoM-PO) hybrid method, this communication explores the electromagnetic scattering from three-dimensional (3-D) isotropic or anisotropic impedance surface, based on an impedance boundary condition (IBC). According to the surface equivalence principle, the electromagnetic scattering can be replaced by the radiation of surface electromagnetic currents in a MoM- and a PO-region, with the currents expanded in Rao-Wilton-Glisson (RWG) vector basis functions. The simulation of impedance surface is performed with the electromagnetic parameters characterized by a surface impedance dyadic. The hybrid method allows for a substantial reduction of computation time and memory requirement, while the numerical results agree well with the exact solutions such as Mie series, which proves the validity of the proposed method. [ABSTRACT FROM PUBLISHER]