**Abstract**

A finite-length segment of filamentous relativistic electron beam (REB), moving uniformly in vacuum, radiates hybrid electromagnetic waves, compound of potential and vortex electric fields, as well as a vortex magnetic field. The strengths of electric and magnetic fields radiated by the segment edges have the opposite signs. The electromagnetic fields in the wave zone are considered as superposition of the electromagnetic waves radiated by the beginning and the end of the REB segment, which, in particular, leads to formation of the field's interference components*.* In both the near and the intermediate zones, there is a flow of electrical energy due to the electric potential field and the field of displacement current.

**Keywords:** relativistic electron beam or REB segment, potential field, vortex field, radiation of EM waves, near field zone, intermediate zone and far field (wave) zone, EM energy flux
