A Graphical aid of the Smith Chart to Analyze the Linear to Circular Polarization Converter Based on Metasurfaces

A comprehensive approach to designing and analyzing the polarization converter based on metasurfaces is carried out by using full-wave simulation method, such as Finite Difference Time Domain (FDTD) and Finite Element Method (FEM). While these approachs are highly accurate, but they lack intuitiveness. In this paper, a graphical method of the smith chart is proposed. The impedance, transmission and reflection coefficients of the metasurfaces can be displayed in the smith chart. The general variation law of them is directly seen in the smith chart, which is very intuitive for designers. Before structural design, an intuitive qualitative physical analysis is performed in the smith chart to obtain a good starting point and phase conditions required by each layer. Then, full-wave simulation method is used to verify the correctness of the smith chart analysis. The best illustration of this analytic and systematic method is probably the development of the metasurfaces-based linear to circular polarization converter from single-layer design to four-layer design in this paper. The proposed method may find important applications in modern metasurfaces-based devices, such as microwave absorber, antennas, radome and so on.