Reflectivity and emissivity of snow and ground at mm waves

A summary is provided of the results of a test program conducted to determine the backscatter and emissivity characteristics of background clutter at millimeter wavelengths. The test was conducted during the late winter time frame to include snow and wet terrain as background types. It is pointed out that active and passive millimeter wave RF sensors are prime candidates for the role of air-to-surface anti-armor weapons applications because of certain advantages compared to microwave sensors and electro-optical sensors. However, the design, development, and evaluation of systems for such an application requires an extensive understanding of the millimeter wavelength reflectivity and emissivity characteristics of clutter and targets. It was found in the investigation that the radar reflectivity of the snow varies strongly with the diurnal freeze-melt cycle. Radar cross sections for short and tall grass are also considered.