In a new experiment a coherent radar has been operated as an interferometer in order to measure the vertical variations of electron density fluctuations in the auroral E region. This was accomplished by placing an outrigger array of yagis in front of the permanent receiving array at the Scandinavian Twin Auroral Radar Experiment radar site in Malvik, Norway. The radar was operated in a mode that allowed the measurement of cross-correlation coefficients between the outrigger antenna and several beams of the receiving array for 25 consecutive backscatter ranges. This provided, for the first time, the capability of studying the backscatter altitude and the dynamic height variations of 1-m auroral irregularities in the E region. In addition, autocorrelations for a number of lags in each of the beams were determined. In this paper we discuss the technique and several experimental details and present results obtained in both the westward and eastward electrojets. We conclude that useful information on relative backscatter altitudes can be obtained from midradar ranges during spatially homogeneous electrojet conditions. Preliminary results show the mean backscatter layer altitude and width undergoing regular variations which often are closely related to concurrent changes observed in the echo intensity and irregularity phase velocity.