Study On The Electromagnetic Scattering From The Non-gaussian Sea Surface

Because of the widely application of microwave remote sensing, sea measurement, oversea target detection and recognition, the theory of electromagnetic scattering from the non-Gaussian rough surfaces is investigated, including part of the scale measurement. The main work is as follows:Based on the Kirchhoff approximation(KA) and the small slope approximation(SSA), the two-dimensional Gaussian rough surface are involved. The comparability of numerical result of the backscattering on the different statistical parameter is expatiated. The derivation of the first-order SSA from the non-Gaussian rough surfaces is examined. Both the corresponding correlated functions and the third- and fourth-order statistic of the skewness and the deviated peakness functions of the Elfouhaily spectrum are studied. The scattering cross sections for the non-Gaussian random surfaces are derived. And the comparison of the backscattering of cross section of the Gaussian and non-Gaussian rough surface by small slope approximation is given and analyzed.The Gram-Charlier series of the non-Gaussian statistics is introduced and the spectrum consisted with the Gram-Charlier PDF are taken into account in the calculation of the radar cross section. The decomposition of the multivariate Non-Gaussian PDF in the sum of a Gaussian PDF instead of the Gram-Charlier series is investigated to solve the appearance of negative probabilities. The theoretical formula is obtained combining with Cox-Munk PDF and the error is considered. The KA and the geometric optics(GO) based of the decomposition of the non-Gaussian are applied to the calculation of the scattering coefficients of the spectrum. The influence of short gravity waves and the long waves on the power series is involved. The diversification of normalized function on the wind speed and the azimuthal angle is also calculated.The ideal electromagnetic scaled theory is derived. The scale condition of lossy dielectric is introduced. Scale measurements of the weak lossy dielectric system are proved by SPM. The influence of variation of statistical parameters of surface on the computing the RCS is analyzed. The two-dimensional surface is simulated by the Monte Carlo method. The scale relationship about high and low wind case is also taken into consideration. The calculation of the variation of the dielectric of the sea constant with the changing of frequency, temperature and salinity is carried on. The scattering coefficients varying with the different dielectric constant is obtained in Ku, K and Ka band. The errors of the RCS resulting from the preparation of the Bruggeman model system are mentioned.