Asymptotic boundary conditions for strip-loaded scatterers applied to circular dielectric cylinders under oblique incidence

This paper describes an asymptotic boundary condition which can be used to model grids of metal strips which are located in free space, inside a material or at a material interface. The boundary condition is asymptotic in the sense that it becomes more accurate the smaller the period of the grid is in terms of the wavelength. The boundary condition is very simple to implement in existing computer programs for calculation of scattering or radiation based on any numerical technique. The method replaces the use of complicated Floquet-mode expansion of the fields scattered by the grid. As an example, we show how to apply the method to calculate the plane-wave scattering from two circular dielectric cylinders under oblique incidence, one loaded with circumferential strips and the other with longitudinal strips. In both cases, analytic series solutions are derived. The results are verified with measurements on cylinders with finite strip periods and widths.