Multi–frequency analysis of the two CSS quasars 3C 43 & 3C 298

We present and discuss observations made with MERLIN and VLBI at 1.7 and 5 GHz of the two CSS quasars 3C 43 and 3C 298. They show quite dierent morphologies, the former being a very distorted triple radio source, the latter a small FRII type object. Relativistic eects and structural distortions are discussed. Source ages are evaluated to be of the order of 10 5 years, therefore 3C 43 and 3C 298 can be considered fairly "young" radio sources. Some inference is also derived on the properties of the medium surrounding the radio emitting regions in these sub-galactic objects, whose density could be as low as 10 3 cm 3 .