A new Ku-band reflectarray with an artificial anisotropic slab that consists of periodic holes, backed by a planar artificial magnetic conductor (AMC) is proposed. The unit-cell of the reflectarray is a two-layered structure that consists of a dielectric with a hole on a grounded patch. The phase diagram of the proposed unit-cell is calculated by a full-wave computational technique, which uses the dyadic Green's function evaluated by an equivalent transmission line modeling in the spectral domain. The obtained dyadic Green's function is used in an integral equation formulated for the surface current densities on the metallic grating. The resultant integral equation is then solved using the method of moments. The required phase shift at Ku-band is obtained by changing the radius of holes in the artificial slab. The introduced unit cell has linear phase range between 13.95 and 14.95 GHz. It is shown that this frequency band is the usable bandwidth of AMC structure. Finally, the designed reflectarray is analyzed using a full-wave electromagnetic solver. The numerical results show a maximum gain of 27.4 dBi, and 48.09% efficiency, at 14.45 GHz with 4.15% 1-dB gain bandwidth for the designed 21 × 21 cm2 reflectarray.