Spectral problem in a generalized theory of electromagnetic waves

It is shown theoretically that electromagnetic process is potentially-vortex. This extends Maxwell's theory. We detected four-dimensional vector potential which is a fundamental characteristic of the electromagnetic field. It has been shown that it describes unambiguously a velocity field of physical vacuum in the selected frame. As in the theory of elasticity, an electromagnetic wave process is described by a superposition of two vectors and two scalar functions. It solved the problem of generating a spectral electromagnetic signal with a predetermined frequency range.