Broadband Optimization of Reflectarray Antennas

This paper presents the broadband design method for reflectarray (RA) antennas. The differential evolution (DE) algorithm has been applied to balance the spatial phase delay errors in the whole work band. A RA antenna consisted of split ring elements has been proposed to validate the method. Numerical analysis and simulation results suggest this optimization an appropriate method to improve bandwidth for RAs. The 1-dB gain bandwidth exhibits a promotion from 8.9% to 15.6%.