Sea-Clutter Measurements on Four Frequencies
NAVAL RESEARCH LAB WASHINGTON DC
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The initial processing and analysis of radar backscatter data, recorded off the coast of San Juan, Puerto Rico, in July 1965, have been completed. Radar returns were collected nearly simultaneously on four frequencies 428 MHz, 1228 MHz, 4455 MHz, 8910 MHz, for both linear and cross polarizations. The data were processed to obtain the normalized radar cross section, sigma of the sea surface as a function of various parameters. In particular, the behavior of the median value of the cross section sigma was investigated as a function of wind direction, incident angle, polarization, radar wavelength, and gross surface conditions of wind velocity and wave height. Results are given for the upwind direction and the linear polarization vertical and horizontal. The polarization ratio is shown to decrease with increasing sea roughness and to be a function of radar wavelength. As surface roughness increases, sigma becomes independent of wavelength for vertical polarization but maintains an inverse wavelength dependence for horizontal polarization. The results given provide estimates of sigma as a function of the above parameters over an angular range of 4 to 90 degrees vertical incidence and from calm sea conditions to moderately rough conditions characterized by 5- to 7-foot wave heights and 10- to 20-knot winds.
- Physical and Dynamic Oceanography
- Active and Passive Radar Detection and Equipment