The increasing demand of higher frequencies technologies in RF (Radio frequency) components, especially for telecommunication, create a need to develop wider and higher frequency bands filters, with optimal performances. Thus, constant effort are made to develop new resonators that outperform excited technologies mainly in terms of electromechanical coupling and quality factor. Excited Bulk Acoustic Resonator XBAR which are composed of a single piezoelectric crystal layer, with metallic electrodes on the top surface, seem to be an interesting solution. It has indeed been shown that it can achieve higher frequency than others acoustic waves propagation technologies. The different characteristics of these resonators are mainly determined by their dimensions and the properties of the piezoelectric membrane. Lithium Niobate has shown interesting piezoelectric properties such as a high phase velocity and large electromechanical coupling which enable wider filter bandwidths. Therefore, using this material in the XBAR represents an attractive way to respond to this flourishing need. The aim of this project is thus to explore the potential of using LiNbO3 substrate with a new orientation. The case of a 128° Y-cut Lithium Niobate LiNbO3 membrane is going to be studied. For that we are first going to review the proprieties of the 128° Y-cut material and how the resonator composed of this substrate has been modeled. Finally, we will search for the combination of geometrical parameters which permits the optimal performance of the resonator.