Future fifth-generation (5G) of cellular systems will use millimeter-wave frequencies and it is expected to offer an extremely wide spectrum and multi-Gigabit-per-second (Gbps) data rates to mobile communications. Hence, mobile devices applied for fifth generation such as antennas seem to be a challenging task. In this article, a single microstrip antenna for the future 5G mobile networks is designed using Rogers RT5880 substrate with dielectric constant of 2.2, which has a simple rectangle shape with small size. The designed structure is proved to achieve large bandwidth and to improved reflection coefficient. Furthermore, simulated results on VSWR, surface current and 3D radiation patterns are presented. Design and simulations in this work are carried out using Computer Simulation Technology (CST) Microwave Studio (CST Suite 2018). This antenna can be considered a good candidate for applications in 5G.