This letter deals with the design of a pair of metasurfaces made of dense periodic arrays of electric dipoles laid on thin metal-backed dielectric substrates, capable of maintaining out-of-phase reflection coefficients over a wide frequency band. Our design is based on the genetic optimization of the dipole dimensions and spacings, and the substrate thickness. For performance assessment and illustration of potential applications to reduction/control of radar cross-section signatures, we present an example involving Bragg-scattering suppression in strip arrays.