Microwave deflectors are periodic structures where a periodic electromagnetic field interacts with ultra relativistic electron beams, in order to analyze the beam properties. Deflectors will be realized and used in the FERMI@Elettra project, that is a soft X-ray fourth generation light source under development at the ELETTRA laboratory (Trieste, Italy). In this paper we present the study performed to satisfy the RF requirements of the high energy deflector, considering both traveling wave and standing wave devices. For the traveling wave case we describe an efficient mode optimization process discussing three different modes, the 2π/3, 5π/6 and the quasi-π. Then we will present a 11 cells standing wave deflector, providing a complete RF design with coupling procedure, sensitivities and other technical parameters.
