Numerical computation of the scattering matrix of an electromagnetic resonator.

A method is presented to investigate diffraction of an electromagnetic plane wave by an infinitely thin infinitely conducting circular cylinder with longitudinal slots. It is based on the use of the combined boundary conditions method that consists of expressing the continuity of the tangential components of both the electric and the magnetic fields in a single equation. This method proves to be very efficient for this kind of problem and leads to fast numerical codes. The scattering matrix that is obtained from this theory can then be used in a multiscattering method to study wave propagation in square arrays of such resonators with an emphasis on the low-frequency behavior.