A Mode-Matching Technique for Analysis of Scattering by Periodic Comb Surfaces

Numerical techniques for calculating electromagnetic fields within three-dimensional surfaces are computationally intensive. Therefore, this paper presents the application of a mode-matching technique developed for analyzing electromagnetic scattering from periodic comb surfaces illuminated by a plane wave. A set of linear equations has been developed to calculate mode coefficients of the field distribution for both E- and H-polarized incident waves. Analysis is performed for two cases where the comb thickness is either infinitely thin or of a finite thickness. The technique is shown to accurately predict both field intensities within the near-field of the periodic surface and far-field scattering patterns. Results are compared to those obtained using the finite integration techniques (FIT) implemented in CST Microwave Studio. Furthermore, numerical results are compared to measurements of an aluminum prototype. Additional far-field scattering measurements using a bi-static system provide additional confidence in CST simulations and the mode-matching methods presented here.