Numerical calculation of the scattered field from a periodic deformed cylinder using the smoothing process on the mode‐matching method

The smoothing process on the mode‐matching method is applied to scattering problems for a periodic deformed cylinder with perfect conductivity. If the body is unaltered on rotation through an angle 2π/ν(ν = 2, 3, 4, …) about some axis, the polyphase wavefunction allows us to deal with the problems only in a sector region with the angle 2π/ν. Consideration of the symmetry of the scatterer reduces the dimension of the linear equations to one part of ν in comparison with the formulation without consideration. The smoothing process together with the improved point‐matching method can be regarded as the computer‐aided algorithm; the algorithm is simple and the accuracy of the solutions can be evaluated explicitly. The numerical results show that the speed of convergence of the solutions by the smoothing process is faster than that of the conventional mode‐matching method, and that for a moderately large truncation size the smoothing process highly improves the accuracy of the solutions. The radar cross section for a non‐convex body is calculated.