This paper presents a wideband reflectarray antenna (RA) based on a nonradiative dielectric (NRD) waveguide with an inserted metal blade for muti-bit phase quantization. The proposed design eliminates the need of resonant components that typically exist in traditional RAs. Additionally, low cross-polarization is achieved by exciting the appropriate propagation mode in NRD waveguide. The beam scanning performance based on multi-bit phase quantization is verified by a series of static prototypes. Compared to traditional rectangular waveguide RAs, the proposed design possesses collimated beam scanning up to 60° without grating lobes, due to the compact unit cell dimensions. At a collimation beam angle of 20°, a 1-dB gain bandwidth of 18 % is achieved with an aperture efficiency of over 40 % and a cross-polarization level of below −40 dB.