  We seek to compute the fraction of the volume of the Universe filled by
expanding cocoons of the cosmological population of radio galaxies over the
Hubble time as well as the magnetic field infused by them, in order to assess
their importance in the cosmic evolution of the Universe. Using N-body
$\Lambda$CDM simulations, radio galaxies distributed according to the observed
radio luminosity function are allowed to evolve in a cosmological volume as
using well defined prescriptions for their expansion. We find that the radio
galaxies permeate $10 - 30%$ of the total volume with $\sim 10^{-8}$ G magnetic
field by the present epoch.
