An enhanced reflectarray (RA) antenna built of elements with reduced reflection phase sensitivity is presented. The proposed unit element is composed of a concentric, multiresonance circular-ring structure with variable sizes. By changing the outer and inner radius of the interior ring in the opposite directions, a reduction in the phase sensitivity to manufacturing inaccuracy is achieved without extra contribution to the 360° phase range and aggravating the losses in the unit element is achieved. In addition, the margin between normal and oblique incidence of a phase response for angles up to 40° is smaller than 10°, which results in a high-efficiency, wideband performance. Measurement results show the maximum gain of 26.4 dBi at 10 GHz, aperture efficiency of 44.27%, and 16.3% 1 dB gain bandwidth. In order to improve the bandwidth of antenna, the phase constant (ψ 0 ) value at the RA aperture is gradually …