Analysis of a reflectarray antenna using microstrip patches of variable size

Microstrip reflectarrays tyically use tuning stubs on each element to adjust the phase of the reflected field. This Letter describes a new approach in which the need for tuning stubs is eliminated and phase control is achieved simply by adjusting the resonant length of the patch elements. The advantages of this approach are described, as are a full-wave analysis technique for computing the phase of the reflected field as a function of patch size and a design curve giving the change in patch size for a desired reflected field phase shift.