An adaptive coherent multifrequency radar system has been developed for several applications. By means of this the velocity distribution (Doppler spectrum) and spectral intensity of 15 different irregularity scales (waves and turbulence) can be measured simultaneously. Changing the azimuth angle of the antennas at regular intervals, the direction of the wave/turbulence pattern on the sea surface can also be studied. Using this radar system, series of measurements for different air/sea conditions have been carried out from a coast-based platform in southern Norway. Experiments in the Atlantic were also performed with the same equipment, making use of the NASA Electra aircraft. There are many air/sea phenomena that play a role in relation to backscattering of radio waves in the microwave region: gravity waves ''modulate'' the capillary wave structure, overturning wave crests produce focusing effects and also periodic regions of strong turbulence, and the boundary layer wind field with strong turbulence amplified by the ocean waves will conceivably leave a patchy and even periodic footprint on the sea surface. Internal waves originating from density gradients in this ocean further complicates the sea surface irregularity pattern. By virtue of the fact that the multifrequency radar allows one to measure the velocity distribution (''coherent and incoherent component'') associated with 15 different ocean irregularity scales simultaneously for several azimuth directions, it is possible to study the different air/sea mechanisms in some degree of detail.