In this literature, scattering from a large Isosceles Right Triangle Groove (IRTG) in a perfect electric plane (PEC) is studied. An efficient Mode-Matching manner involving physical optics approximation is applied to a large IRTG. Considering two synthetic PEC walls over the groove, the tangential fields inside and outside of the groove are expanded as the sums of infinite harmonics modes. By applying the boundary conditions, the modes are matched on IRTG and a linear system of equations based on series coefficients is constructed. Since matrix elements are computed analytically, finding the inverse an N×N matrix is the most time-consuming operation in this manner. The obtained results are verified by two full numerical techniques MoM and FEM.
This study developed a generalized solution based on modal expansion for scattering by large cavities with known wave functions placed in an infinite perfect electric plane. Under the assumption of a large cavity, to reduce simulation time and simplify expressions, the half‐space above cavity with a strong singular Green's function is substituted by an arbitrary semi‐waveguide. The fields inside the cavity are expanded by the semi‐waveguide eigenfunctions. The corresponding modes are matched to create a system of linear equations for unknown expansion coefficients. To demonstrate the validity and ability of this method, it is applied to several grooves with different shapes (triangular, circular, and elliptical grooves) and then their scattering signatures are compared with each other. The results are also verified by the results obtained by the method of moment. The measured simulation time for both methods shows that this scheme can be an appropriate candidate for analysing the scattered fields by large cavities.
An asymptotic solution based on high-frequency approximations is proposed to determine the scattered waves from a wide empty isosceles triangular cavity. The modal method based on cylindrical wavefunction expansion with the physical optics technique is used to find analytical expressions for the unknown expansion coefficients and significantly improve the time efficiency of calculations. Some assumptions and simplifications are made to reduce the complexity of the problem while still being accurate for wide triangular cavities. Comparisons are achieved to illustrate the validity and time efficiency of the suggested solution.
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