As you know we live in the era of technology therefore, communication is developing. Needing for radars and wireless communication systems for making communications with far distances has been increasing. One of the main elements of these systems is high-gain antenna so parabolic reflectors or arrays are suitable choices. Parabolic reflectors need uniqe curve to creat every special pattern, obtaining curve equations and manufacturing are very complicated. On the other hand these type of antennas don’t have wide angle beam scanning capability. The array antennas have the ability to scan electronically with controllable phase shifters. They are not economical due to expensive amplifier modules and phase shifters. Finally by presenting the “Reflectarray”,combination of reflector antenna and array antenna these problems are solved. Primary types of such antenna were not acceptable because of huge and heavy structure. Since the reflectarrays use printed microstrip, they are welcomed and it makes possible achieving reflectarray surface with low mass,volume and cost. But the reflectarrays has disadvantages such as narrow bandwidth that caused by narrow bandwidth of microstip patch elements and the differential spatial phase delays. In order to overcome this problem a more compact configuration called “Folded Reflectarray Antenna” has been proposed. In this thesis at first simulation of a reflectarray antenna in 12.5GHz that fed by rectangular horn has been done. Then a novel element is designed which compared to the element of reflectarray antenna have better polarization isolation. So we use it to design a folded reflectarray antenna in 13.5GHz. Also we design and simulate two polarizer in 13.5GHz and 60GHz for two folded reflectarray antennas that are simulated too. Key Words :Reflectarray, Folded Reflectarray Antenna, Printed Antenna, Polarizer