Reflectarray antenna is realized by rectangular dielectric resonators with fixed height, width and variable length for linear polarization in X-band. The reflectarray is center-fed by linearly polarized pyramidal horn antenna. The reflectarray is designed based on the analyses of a single cell of a periodic array. The full-wave analyses are based on the finite integration technique. In these analyses the mutual coupling between array elements and the feeding horn and the edge diffraction from the ground plane are considered. At 10 GHz, the antenna provides a 3-dB beamwidth of 8 degree with a gain of 27 dB. The antenna bandwidth within 1dB gain variation is found to be 8%.