This bachelor thesis is dealing with matters of data communication after power line. The thesis is including the PLC systems history, current possibilities of utilization and different types of modulations being used, interference sources and parameters of a transmission line. We will elaborate on methods of transmission line modeling and one of them will be used in the practical part of the thesis. The practical part consists of modeling of different types of topology and impedance endings applying generation of random transmission parameters and sizes of typology. We analyze results from practical measurement which are incorporated in a model. The model is then being compared with another one in terms of fixed parameters