Figure - available from: IET Microwaves, Antennas & Propagation
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The geometry of (top) the soft‐hard strip and (bottom) the hard‐soft strip illuminated by the incident plane wave with (top) Ez‐polarisation and (bottom) Hz‐polarisation
Source publication
Diffraction at a strip with one face soft (electric) and the other hard (magnetic) is studied. New results obtained by the method of moments (MoM) are compared with the asymptotic theory of edge diffraction (TED) for the totally soft and hard strips. Attention is given to diffraction of oblique incident waves including the grazing diffraction. Nove...
Citations
... As a result, two-dimensional problems play a critical role in the initial validation of the proposed methodology or design [8]. The study points out that previous studies have primarily focused on various geometries, boundary conditions, sources, polarisations, surface characteristics and edge conditions in two-dimensional scattering problems [9][10][11][12][13][14][15]. Traditionally, the perfect electric and magnetic conducting surfaces have been studied with the Dirichlet and Neumann boundary conditions, respectively [16]. ...
... When the source is located inside the circular strip, the comparison with the PEC case is provided in Figure 4. In Figure 5, the validation of convergence is demonstrated by increasing the truncation of the number of unknowns (p) in Equations (13), (15), (16), and (17) for the cases when the source is inside and outside the circular strip, respectively. For Perfect Magnetic Conductor (PMC) cases or situations close to PMC, the tangential component of the H-field on the surface of the circular arc should be zero (Figure 5a,b). ...
... Consequently, the ratio between the total field and the incident tangential components approaches zero as well on the surface. As observed, the convergence is slower for the case of the source inside the circular strip, and truncation of p in Equations (13) and (15) should be greater than 10 to achieve an error of less than 7%. However, the analytical-numerical method possesses an advantage in that the convergence is rapid for the approximate solution. ...
The authors investigate electromagnetic scattering by a circular strip with impedance boundary conditions in detail. The excitation is obtained by the H‐polarised line source and the impedance boundary condition with different impedance values on each surface of the circular strip is imposed. Electromagnetic scattering from circular strips is formulated employing an integral equation approach including the orthogonal polynomials while expressing the current densities on inner and outer surfaces. To consider the edge condition, the current density on the scatterer is expressed in terms of Gegenbauer polynomials with the weighting function. Unlike the previous studies, the authors investigate the behaviour of the EM field regarding the location of the cylinder source, the size of the aperture and the different impedance values. The convergence of the proposed approach, which is one of the analytical–numerical methods, is investigated for different impedance values; considering the results, resonators with impedance surfaces of certain complex values and certain locations of the cylinder source perform better than the known PEC and PMC resonators for some specific resonance cases. An effective analytical–numerical approach is proposed for such geometry with the impedance boundary condition. An extensive analysis and comparison with other methods are provided. The limit cases of the impedance boundary condition (Dirichlet and Neumann boundary conditions) are validated.
... The method of Moments has a singularity problem when the boundary conditions are required on the surface. To avoid the singularity, Method of Moments uses the regularization technic or tries to find an analytical solution for the self-terms in the matrix equation [1][2][3][4]. On the other hand, the method of auxiliary sources for example considering the analytical nature of the field at the boundary and by the analytical continuation of the scattered field, the sources are shifted inside or outside of the corresponding surface [5][6][7]. ...
... where 0 (1) − is Hankel's function of zero-order and the first kind and corresponds to the Green's function of the equation, ( ′ , ′) stands for the source point, = 2 / is wavenumber and stands for the magnetic permeability. To solve (1), there are many methods are developed [1][2][3][4]. Here, the Method of Moments (MoM) approach is employed [1,2]. ...
... Similarly, the scattered Electric field can be found with (4). It is clear that for each ( , ) in the double integral above, the value of the integral would be the same since −( √( ′ − ) 2 +( ′ − ) 2 ) 2 is constant because the integration is taken around ( , ) . ...
In the present study, a new methodology for solving an eigenvalue problem and the two-dimensional E-polarized electromagnetic wave diffraction by the arbitrary shaped perfect electric conducting (PEC) scatterers is proposed. The approach is based on the Gaussian basis function and the Regularized Hankel's function. The study provides the theoretical background of the newly proposed approach in detail. By expanding the current density on the surface with the summation of Gaussian functions and approximating the Hankel function with regularization leads to having a simpler, compact, and novel approach to investigate the behavior of the electromagnetic field in the vicinity of the obstacles. Also, the numerical results including the comparison with the other methods are provided. The outcomes reveal that the proposed method can be employed for such a class of diffraction problems to solve the problem, numerically.
