Reflectarray composed of 23 x 23 elements covering an area of 276 x 276 cm2 is constructed. The unit cell consists of rectangular DRA, a slot in the ground plane, a dielectric layer, and a conducting ground plane. The full phase of 360 degree of the array elements can be obtained by using two slot-ground plane sizes. The reflectarray is centred fed by linearly polarized pyramidal horn antenna. Full-wave analysis using the finite integration technique is applied. The mutual coupling between the feeding horn and the elements of the reflectarray are considered. At 10 GHz, the antenna provides a 3-dB beamwidth of 6 degree with a gain of 28 dB. The antenna bandwidth within 1dB gain variation is found to be 13% and aperture efficiency of 59%.