METHOD OF DIFFERENTIATING ANOMALIES ON WATER SURFACE BY MULTI-FREQUENCY MICROWAVE RADAR Russian patent published in 2017 - IPC G01S13/88 

FIELD: radio engineering, communication.

SUBSTANCE: signals are emitted and received, scattered by the water surface in the microwave bands (LX-bands) on two polarizations (HH and VV) for two frequencies separated by not less than one and a half times at a certain observation angle. Herewith the observation angle is chosen in the range of 50-80° from the vertical. As the characteristics of the received signals, the difference of the measured specific effective scattering areas of the received signals on two polarizations for each of the two frequencies is used. The obtained values of the differences determine the experimental values of the wave intensities at the Bragg wave numbers. At the same time, the average wind speed is measured. For the measured average wind speed, theoretical background wave intensities at Bragg wave numbers are calculated using the model spectrum. Spectral contrasts of waves on the water surface are obtained as the ratio of the theoretical background values of the wave intensities at the Bragg wave numbers to the experimental values of the wave intensities at the Bragg wave numbers for both frequencies for the measured average wind speed. A decision is taken on the presence of an anomaly on the water surface on the basis of the magnitude comparison of the spectral contrast of waves on the water surface at the maximum of the Bragg wave numbers with a certain threshold value. The ratio of the obtained spectral contrasts is calculated. It is concluded that there is a film slip or a calm zone on the water surface based on the position of the contrast ratio value found for the measured value of the average wind speed relative to the semiempirical curve of the contrast ratio relationship to the wind speed at a certain observation angle: if the value is above the curve, the film slip is observed, if it is below - the calm zone is observed.

EFFECT: increasing the accuracy of anomalies on the water surface.

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