Enhanced Reflectarray Antenna Using Elements With Reduced Reflection Phase Sensitivity

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 ( $\psi _{{{\circ}}}$ ) value at the RA aperture is gradually tuned and optimized. The designed antenna with $\psi _{{{\circ}}}= \,{{- {\text{125}}^\circ }}$ has a peak gain 26.6 dBi at 10.2 GHz and aperture efficiency of 44.56%, and the 1 dB gain bandwidth is about 23.3% (9.67–12 GHz). In comparison with the conventional antenna ( $\psi_{\circ}= {{0^\circ }}$ ), the 1 dB bandwidth shows a 43% improvement.