Back Scattering from Water and Land at Centimeter and Millimeter Wavelengths

The back scattering from water and several land terrains has been measured at wavelengths of 3.2 cm, 1.25 cm, and 8.6 mm using vertical polarization only. σ°, the average radar cross section of water or land echo per unit area of the surface, has been plotted as a function of the angle of incidence for the three wavelengths. A family of curves at each of the three wavelengths shows the change in σ° with wind velocity for the water surface. σ° is also shown as a function of the angle of incidence for several land terrains. In general, σ° increases with frequency and also with wind velocity in the case of the water surface.