Accurate electromagnetic modeling of liquid crystal cells for reconfigurable reflectarrays

An electromagnetic modeling has been presented for an accurate analysis of reconfigurable reflectarray cells based on liquid crystals (LC). The proposed modeling considers both the inhomogeneity and anisotropic effects, which are calculated by using a simplified molecular model for the behavior of the LC when it is excited by an electrostatic field. The inhomogeneity of the LC is analyzed by dividing the LC volume in several homogeneous building blocks. The convergence of the number of blocks required to provide an stable phase-shift is discussed, and the errors produced when the conventional assumptions are used for the behavior of the LC (homogeneity and isotropy) are also analyzed. For printed dipoles, which are suitable to minimize the capacitive coupling between cells and to get a wider phase range, it has been proved that these errors can exceed 60°, and therefore are not negligible in the most common applications.