Characteristic mode analysis of reflectarray unit cell

In this work, characteristic mode analysis for unit cells of metal-only periodic structures such as reflectarrays, transmitarrays and frequency selective surfaces (FSS) is presented. Ewald’s representation of three dimensional (3-D) Green's function for two dimensional (2-D) periodicity is utilized within the Method of Moment (MoM) analysis. Modal characteristics of reflectarray antennas are investigated. Relation between characteristic modes and the reflection coefficients for reflectarray antennas is discussed. It is concluded that the theory of characteristic mode (TCM) can be exploited for the design and analysis of reflectarray antennas.