Pole-zero matching technique for multilayered periodic structures with application to the 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, a pole-zero matching technique is applied to the determination of the scattering matrix of periodic arrays of stacked rectangular microstrip patches as a function of the dimensions of the patches. The pole-zero matching technique makes it possible to obtain closed-form equations for the scattering matrix of the periodic structures from a reduced set of full-wave data. These closed-form equations are very useful because they lead to important CPU time savings when they are applied to the design of reflectarray antennas. In fact, in this paper we present a comparison between a reflectarray design based on a full-wave analysis of each element and a reflectarray design based on the derived closed-form equations. It is shown that the CPU time required by the full-wave approach is nearly one order of magnitude larger than that required by the approach based on closed-form equations.