Analysis of Microwave Emission of Exponentially Correlated Rough Soil Surfaces from 1.4 GHz to 36.5 GHz

We analyzed the microwave emission from a rough soil surface with exponential correlation by characterizing its dependences of polarization, look angle, and frequency. Using the same set of physical surface parameters of rms height and correlation lengths, results are obtained for a wide range of frequencies at 1.4 GHz, 5 GHz, 10 GHz, 18 GHz, and 36.5 GHz. Accurate simulations for the 2-D scattering problem are conducted by Galerkin's method with the rooftop basis function, followed by near-field integration, fine discretization, and cubic spline interpolation of surfaces. The multilevel UV method was employed to accelerate the solution. Accuracy is ensured by energy conservation check. Simulation results are compared with SPM, KA and AIEM. Results suggest that there exists distinct emission characteristic between the exponential and the Gaussian correlated surface. These charcateristics should be very useful in developing retrieval algorithm of the soil moisture from emissivity measurements.