Method of calculation of electroweak characteristics of mesons in the Poincaré invariant quantum mechanics

On the basis of the point form of Poincaré-invariant quantum mechanics, a method for calculating the formsfactors and the decay constants of mesons, as relativistic coupled quark systems, is presented. As an example of the developed technique, an integral representation of the radiative decay constant of a vector meson $V\to P\gamma$ is obtained.