Nowadays, in practice, when it is required to calculate electromagnetic fields, the use of some mathematical model is of great importance. Because, with the help of this model, it is possible to express the propagation of electromagnetic waves in real conditions. One of them is the plane electromagnetic wave model, which can be used to calculate many wave processes. Let's first understand a little bit about the plane electromagnetic wave. In this, first of all, it is necessary to learn the concept of wave front or wavy surface.