The work in this thesis focuses on the study of rectangular printed antennas operating at the frequency fr=3.5 GHz. These structures can be used in 5G systems, which represent an interesting revolution in mobile technology. To this end, we first clarified the location of patches in 5G systems, presenting the general structure of such a system, the frequencies used for this generation and the various applications developed thanks to the advantages posed. We then turned our attention to patch antennas, focusing on structure, feed types and the theoretical microstrip study that determines the initial antenna dimensions we can use for design.Finally, we moved on to the design of a rectangular patch antenna at the frequency fr=3.5 GHz, following the steps required to build the structure: dimensioning, model drawing, boundary conditions and circuit excitation. For the simulation, we used the HFSS software.