Application of Cylindrical Near-Field Measurement Technique to The Calibration of Spaceborne Radar Antennas: NASA Scatterometer and SeaWindsModern spaceborne radar scatterometers such as the NASA Scatterometer (NSCAT) and SeaWinds radar instruments require precise determination of the normalized backscattered radar cross section within a few tenth of a decibel in order to achieve the desired wind velocity and direction measurement accuracy of 2 m/s and 20 degrees respectively.