A radar measurement apparatus works according to the FMCW principle and includes a radar transmission unit, and a radar receiving unit, which is designed to receive a radar received signal reflected on a surface of the medium or other target in a pipe or tube, to convert the received signal into an intermediate frequency signal by mixing with the transmission signal, or a signal derived therefrom, and based on an intermediate signal to determine distance to the surface of the medium or other target. The radar receiving unit applies a phase correction to the intermediate signal produces a phase corrected, intermediate frequency signal, wherein the phase correction lessens or removes a dispersion dependent phase fraction in the phase of the intermediate signal and adds a non-dispersion effects dependent phase fraction. The radar receiving unit is designed based on the phase corrected intermediate signal to determine the target frequency components in the intermediate frequency signal and based on the target frequency components to determine distance to the surface of the medium or other radar.