Design of phased array microwave scatterometer with digital beam forming technique in active and passive combining observation system for sea surface salinity

Active and passive combining observation microwave instrument combines L band one dimension push-broom synthetic aperture radiometer and L band array mode microwave scatterometer to make accurate measurement for sea surface salinity. In this system, microwave scatterometer provides the information about the sea surface roughness, one of the main sources of error for salinity measurement. Phased array mode is adopted in scatterometer and the array elements are arranged between two elements with the largest baseline of radiometer. The number of array elements is set to 7 and digital beam forming technique is used to get scanning in cross azimuth direction. Then same footprints with radiometer can be obtained. Narrow band chirp signal is used to get range resolution. In this way, accurate backscattering information corresponds to observing area of radiometer can be achieved and then sea surface roughness can be derived. Finally, the error coming from surface roughness can be corrected.