Analysis and design of dual frequency reflectarrays using microstrip stacked patches of variable size

A new stacked microstrip reflectarray based on patches of variable size has been proposed for dual frequency operation. A progressive phase distribution is achieved at both frequencies by adjusting the length of the patches in each elementary cell of the reflectarray. The phase of the reflection coefficient in each cell is computed by a full-wave method, assuming periodicity. A numerical optimization is used to find the dimensions of the patches that provides the appropriate phase distribution