Scattering by a Two-Dimensional Periodic Array of Vertically Placed Microstrip Lines

Scattering by a two-dimensional (2-D) array of vertically placed microstrip lines is important for a number of recently proposed interesting applications. We investigate this scattering problem using an efficient full-wave mode-matching method. Our analysis comprises two parts. First, the propagation characteristics of the 2-D array are studied by solving a unit-cell of this structure, which is a microstrip line sandwiched between two periodic boundaries. In the second part, an air-to-array discontinuity is solved using Floquet modes in the air-region. Based on our full-wave analysis, we then present two frequency selective surfaces using this array, which exhibit stable quasi-elliptic filtering response under a large variation of the angle of incidence. Results of our full-wave analysis are in excellent agreement with those obtained from measurements and CST Microwave Studio.