Surface Waves Investigation and Monitoring instrument (SWIM)

Surface Waves Investigation and Monitoring (SWIM) is the rotating multi-beam Ku-band radar on CFOSAT for significant wave height and directional ocean-wave spectra.^[1][2] It operates at 13.575 GHz with 320 MHz bandwidth and on-board digital range compression for the backscattered signal.^[1][2] Six beams cover nadir through 10 degrees of incidence, at 0, 2.4, 4, 6, 8 and 10 degrees.^[1] The rotating antenna provides a 180 km swath and an approximately 18 km by 18 km footprint at 500 km altitude.^[1][2] The instrument rotation rate is 5.7 rpm, with a 5.6 rpm alternate for the same scan.^[1][2] SWIM demonstrates radar altimetry on CFOSAT, and its low-incidence rotating beams are used for wave-spectra measurement in addition to altimetric ranging.^[1][2] SWIM is active on CFOSAT, with end of life at least 2026 and follow-on use on HY-2L/CFOSAT-FO from 2030 to 2038.^[3][1]