A new radar technique suitable for high resolution studies of narrow scattering layers in the atmosphere is introduced. The positions of the layers within the radar scattering volume are deduced from the phase differences between radar returns at two distinct transmitter frequencies. Initial mesospheric observations demonstrate the applicability of the technique, and show that the scattering layers are often a few hundred meters thick and widely separated in the mesosphere. Their vertical motions are generally consistent with vertical Doppler velocity estimates.