Radiometric measurements of the microwave emissivity of foam

Radiometric measurements of the microwave emissivity of foam were conducted in May 2000 at the Naval Research Laboratory’s Chesapeake Bay Detachment using radiometers operating at 10.8 and 36.5 GHz. Horizontal and vertical polarization measurements were made at 36.5 GHz; horizontal, vertical, +45, 45, left circular, and right circular polarization measurements were obtained at 10.8 GHz. Surface foam was generated by blowing compressed air through gas permeable tubes supported by an aluminum frame and floats. Video micrographs of the foam were used to measure bubble size distribution and foam layer thickness. A video camera was boresighted with the radiometers to determine beam-fill fraction of the foam generator.