Electronically tunable reflectarrays and amplifying reflectarrays have attracted considerable research in recent years, however, little work has been done to combine these two features simultaneously in a single design. This paper focuses on the design of such a reflectarray, which can be used as a high gain, reconfigurable transmitting antenna for communication links. The reflectarray element is an aperture-coupled microstrip patch that accepts a linearly polarized wave, phase shifts and amplifies the guided-waves in the transmission lines, and then re-radiates an orthogonally-polarized wave. First, the element design, modelling, stability analysis and experimental results are presented. Then a 48 element reflectarray prototype operating at 5.7 GHz is described and its two dimensional beam steering capability and amplifying nature are successfully demonstrated and verified.