The development of a microwave radiometer for use as a highway ice detector

A system capable of detecting snow, ice, frost, or slush over a highway bridge deck area greater than 4 x 2 feet (1.2 x 0.6 m) was developed and a valid alarm signal to warn motorists of a hazard was determined. The detection system selected was a microwave radiometer operating at 10 GHz which continuously samples a reference noise source and internal amplifier noise to provide measurement corrections of radiated power received from the road surface being observed. Principal radiometer components are: rectangular horn antenna; sensitive receiver; and signal processor/alarm unit. The successive program phases were: (1) design optimization and system tradeoffs; (2) breadboard model laboratory and field tests; and (3) prototype model design, fabrication and test. Test results on asphalt and concrete roadway simulators, as well as actual asphalt roads, correlated with previously published radiometric temperatures for similar surfaces.