A systematic study of the electron Bernstein wave (EBW) emission from either overdense plasmas or plasmas with moderate electron temperatures is presented. Starting from description of the bare electrons microscopic thermal radiation we finally arrive at the macroscopic expression for the radiation temperature. The latter is shown to be a sum of the electron temperature and a fluctuating piece caused by the fluctuations of both the EBW emission source and the EBW damping rate within the ECR layer. It is shown that the correlation measurements of the EBW emission at two separate frequencies reveal information on the correlation length of the low frequency turbulence.