  We report the results of flux density measurements in the extended components
of thirteen giant radio galaxies, made with the RATAN-600 in the centimeter
range. Supplementing them with the WENSS, NVSS and GB6 survey data we
constructed the spectra of the studied galaxy components. We computed the
spectral indices in the studied frequency range and demonstrate the need for a
detailed account of the integral contribution of such objects into the
background radiation.
