Doppler Spectra in Microwave Scattering from Wind Waves

Doppler spectra in microwave scattering from wind waves have been measured at X band (3.2 cm) and K band (1.25 cm) in a short fetch wind wave tank. The scattering cross sections, mean frequency shifts, and bandwidths obtained are compared with results of measurements of the directional slope spectra, mean drift, and particle velocities of the wind waves. The scattering is attributed to low order Bragg scattering, the phase speeds of the wind waves are deduced and the dependence of the Doppler bandwidth on wind speed and Bragg wavenumber is given.