Antenna, as indispensable part of communication system, finds its applications in various technologies area such as: mobile systems, radar systems, Internet technologies, medicine, industry, home applications, traffic etc. Functionality of an antenna hugely depends on its parameters, while they depend on the antenna geometry. This thesis first describes the antenna parameters. Then we used the program NEC2 to model and simulate several antenna structures, starting with the half-wave dipole as the simplest one, serving as a reference antenna, and ending with the more complex structures like the antenna arrays, made of several half-wave dipole located in the same plane. In order to increase the gain (one of the main antenna parameters) we put several dipoles in front of the reflector, which is made of copper panel. That way we built the antenna array which is commonly used as a sector antenna in base stations. The antenna was designed for the frequency of 2.4 GHz. After performing the simulations, we constructed the physical antenna array in the laboratory and measured its gain and impedance matching. According to the obtained and analyzed results, we found that the antenna is not matched at the designed frequency, but at a higher one. Its measured gain also deviates from the simulated model. These discrepancies may result from several factors, the imperfection of the realized geometry likely being the dominant one.