Modelling X-band sea clutter with the K-distribution: Shape parameter variation

Performance modelling techniques for maritime radar target detection problems typically make use of a parametric probability distribution for the background ocean backscatter. In this paper, measured X-band sea clutter is analysed by fitting a K-distribution and the variation of its parameters with radar resolution, polarisation, viewing grazing and azimuth angles and ocean wind and wave conditions is examined. Grazing angles lie in the range 10° to 45°. Earlier work has already characterised the variation in the mean of the distribution. Here, the shape parameter υ is studied. Surprisingly, it is found that υ exhibits a sinusoidal like variation with azimuth angle which is aligned with the direction of the wind waves rather than the swell.