On Describing the Radiation and Diffraction of Electromagnetic Waves by the Eigenfunction Method

We consider applicability of the eigenfunctions of the integral operator to solution of the inner problem of electrodynamics (finding the source function of the electromagnetic field) by the method of moments. It is shown that the eigenfunctions can be determined on the basis of solving the complete eigenvalue problem for the moment matrix. In this case, this procedure has a better computation stability compared with the procedure for calculating the characteristic modes of the integral operator, which is based on the same scheme and has gained a wider spread at present. As an example, we consider the problem of diffraction of a plane electromagnetic wave by a helical particle, which is solved by the eigenfunction method. The results of numerical modeling are presented.