Performance comparison of different element shapes used in printed reflectarrays

A systematic study of the performance of reflectarrays with different element shapes is presented. The reflection properties of the printed elements versus their geometrical dimensions are calculated by using the method of moments (MoM)/boundary integral-resonant mode expansion (BI-RME) method, which permits the analysis of arbitrarily shaped elements. In order to compare the element performance, four parameters are defined as "figures of merit": the range of the reflection phase; the sensitivity to fabrication tolerances; the bandwidth; the cross-polarization level. Both classical (e.g., rectangles and rectangles with tuning stubs) and novel element shapes (e.g., ridge, dogbone) are considered in the case of single-layer structures; the novel proposed shapes exhibit a good tradeoff of all the figures of merit. Double-layer structures are also analyzed, which prove their superior performance at the cost of an increased fabrication complexity.