  In this paper, we discuss the low frequency spectrum of SN 1993J with GMRT.
We observed SN 1993J at several epochs in 20cm, 50cm, 90cm and 125cm
wavelengths and achieved near simultaneous spectra. We fit synchrotron self
absorption (SSA) and free-free models to the data. We compare the size of SN
obtained using SSA fits to that of size extrapolated from VLBI measurements at
various epochs using public data at earlier epochs. We find that the
synchrotron self absorption process is insufficient to reproduce the observed
size of the supernova under the assumption of equipartition between magnetic
fields and relativistic electrons. We also derive the evolution of spectral
index and magnetic field at several epochs.
