STUDY OF DOPPLER SPECTRA OF RADAR SEA-ECHO

Doppler spectra of radar sea-echo were investigated theoretically and experimentally. Electromagnetic scattering models were developed with composite rough surfaces, i.e., Bragg resonant water waves superimposed on a carrier water wave and basic concepts in hydrodynamics were developed for a gravity were of finite height. New experimental results on spectra of radar sea-echo from the Four-Frequency Radar 428 MHz, 1228 MHz, 4455 MHz, and 8910 MHz, for sea conditions which ranged from 1 to 2 ft waves and 1 to 2 knot winds to 26-ft waves and 46 to 48 knot winds, show that the bandwidth of radar sea-echo is polarization and frequency dependent, and the differential doppler, between horizontal and vertical polarization, is frequency and depression angle dependent. Both the noisiness of the spectra and the greater spectral width of the horizontal return indicate spray over the sea might be the mechanism responsible for the dependencies observed.