A design of a directive antenna based on a Fabry-Pérot cavity is described, using a single metallic partially reflecting surface (PRS) in front of a coaxial-fed patch antenna. The main features of this type of antennas are their low profile and single feeding point. The design is initially carried out following an approximate ray model analysis using the extracted PRS characteristics from electromagnetic simulations. The antenna performance is also simulated, obtaining a directivity of 20.6 dBi for 15.25 GHz, and verifying its predicted behaviour. Furthermore, a prototype is manufactured at the group premises and some preliminary measurements are presented.