Design and implementation of a broadband center-fed single-layer reflectarray antenna is studied in this letter. Each element in the proposed reflectarray consists of a circular patch attached to a variable-length single phase-delay line to achieve more than 1000° linear phase range within 10.8~12.8-GHz frequency band. The main characteristic of the proposed element is its large linear phase range, which increases the bandwidth and performance in reflectarrays. Using a special arrangement of elements enables the reflectarray to achieve a low cross polarization. Measurement results show a maximum gain of 26.2 dB at 11.8 GHz, and 17% 3-dB gain bandwidth in the range 10.8~12.8 GHz.