Radar waves penetrate deeper into materials with low dielectric constants and reflect more efficiently from those with high constants. Moist soils have values typically between 30 and 60. Thus, variation in reflected-pulse intensities may indicate differences in soil moisture, other factors being constant. Variations among rocks is generally too small to distinguish most types by this property alone. The second material property is roughness.
Materials differ from one another in their natural or cultivated state of surface roughness .
Examples include the surficial character of pitted materials, granular soils, gravel, grass blades, and other covering objects whose surfaces have dimensional variability on the order of millimeters to centimeters. Radar Penetration Radar wavelengths also influence penetrability below target tops to ground surfaces. L and P band radar penetrate deeper than K or X bands. In forests, shorter wavelengths, such as C band, reflect mainly from the first leaves encountered, thus, from the canopy tops. At longer wavelengths, most tree leaves are too small to have much influence on backscatter, although branches will interact, so that canopies are penetrated to varying degrees.