Efficient analysis of multi-resonant periodic structures for the improved analysis and design of reflectarray antennas

In order to design reflectarray antennas within reasonable CPU times, fast and accurate numerical tools for the analysis of periodic multilayered structures are required. In this paper the method of moments in the spectral domain (MoM-SD) based on multilayered Green´s functions (MGF) is applied to the analysis of periodic structures containing multilayered stacked patches in the unit cell. These multiresonant cells are potential elements for the design of reflectarray antennas. In the paper we show that the use of basis functions with edge singularities in the approximation of the current density on the patches leads to important computer memory and CPU time savings in the analysis of the periodic structures. Also, a rational fitting technique is introduced which makes it possible to obtain closed-form expressions for the scattering matrix of the periodic structures in terms of the dimension of the patches used to adjust the phase of the reflectarray elements.