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A circularly polarized wideband reflectarray is presented using a monofilar single-turn helical antenna as reflecting element. An <inline-formula> <tex-math notation="LaTeX">$11\times 11$ </tex-math></inline-formula> elements reflectarray is designed, simulated and measured in X-band which demonstrates a wide bandwidth and large-angle beam-scanning performance. Phase range of 360&#x00B0; is obtained by rotating off-centred reflecting elements. Full wave simulations show that 1-dB bandwidth of 29.1&#x0025; is achieved at the center frequency of 10 GHz with a maximum gain of 23.9 dB at normal angle of incidence (<inline-formula> <tex-math notation="LaTeX">$\boldsymbol {\phi }$ </tex-math></inline-formula> &#x003D; 0&#x00B0;, <inline-formula> <tex-math notation="LaTeX">$\boldsymbol {\theta }$ </tex-math></inline-formula> &#x003D; 0&#x00B0;) where the measured gain for the focused beam is 23.6 dB with an aperture efficiency of 51.7&#x0025;. Simulated and tested axial ratio is less than 3 dB from 8.9 GHz to 10.7 GHz. Moreover, large-angle beam scanning performance is verified by changing the angle of incidence from &#x002B;30&#x00B0; to &#x2212;30&#x00B0; in both orthogonal planes and maximum gain loss is tested to be less than 1.3 dB at all scanned angles. Feasibility of design is demonstrated by the measured radiation performance and the results are in good agreement with the simulations.