Development of a dual band circularly polarized microstrip reflectarray

The development of a dual-band circularly polarized microstrip reflectarray in Ka-band is presented. This reflectarray is composed of a set of cross dipole cell elements for each band that are etched in an interlaced lattice configuration. Two reflectarrays based on single and double layer configurations are introduced. Adjusting the length of orthogonal dipoles of the same cell element to maintain 90° relative phase shift between their re-radiated fields, will result in a reflectarray that converts an E-field that is linearly polarized along the bisector of the orthogonal dipoles into a circularly polarized field. Measurement results demonstrated 36% radiation efficiency and axial ratio better than 2.0 dB for 3% bandwidth for both bands and for both configurations.