Dielectric constant values of the samples of powders (at various moist states) have been calculated using wave guide cell method at a single microwave frequency 9.78 GHz at 330C. The Backscattering coefficients for rough and bare soil surfaces soil σ are calculated by Small Perturbation Model (SPM). Fresnal reflectivity of the soil surfaces which is an input parameter for SPM is calculated using the values of dielectric constant of the soil (at different wetness) and observation angle as input parameters. The roughness of soil in SPM is characterized by RMS height and correlation length and isotropic Gaussian auto correlation function. The radar backscattering coefficient of vegetative soil surface is determined by water cloud model. The total back scattering coefficient is calculated adding the contribution of the vegetation, veg σ and that of the modified effect of underlying soil. The effect of vegetation canopy on the backscattering from bare soil surface is modified by a parameter vegetation transmissivity τ. The present study reveals that radar backscattering coefficient for bare soil surface soil σ and vegetative soil surface σ has a respective correlation with SMC of the soil. Further, soil σ and σ decrease as the angle of observation increases.

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References

1. Attema, E.P.W. and Ulaby, F.T. 1978. Vegetation modeled as a water cloud. Radio Science, 13, pp.357–364.
2. Bindlish, R. and Barros, A.P. 2001. Parameterization of vegetation backscatter in radar-based soil moisture estimation, Rem. Sensing of Env, Vol. 76, pp. 130–137 Engman, E.T. and Wang J.R. 1987. Evaluating roughness model for radar back scatter, IEEE Trans. Geosci. And Remote sensin, Vol GE–25, No 6.
3. Hui, L., Toshio, K., Hiroyuki, T., Tobias G. and David.,A. 2008, Monitoring Winter Wheat Growth With Ground Based Microwave Radiometers (GBMR) 2008. IEEE International Geoscience & Remote Sensing Symposium July 6–11, 2008 Boston, Massachusetts, U.S.A.
4. Jangid, R.A., Neeru, Bhatnagar, D. and Gandhi, J.M. 1996. Microwave probing to study particulate behaviour of basic powdered materials. Indian J. of Pure and Appl .Phys ,34, pp. 316–18.
5. Kong, J.A. 1990. Electromagnetic Wave Theory. Wiley. 2nd Ed. New York.
6. Paloscia S., Macelloni G., Pampaloni P. and Sigismondi S.,1999. The potential of Cand L-Band SAR in estimating vegetation biomass: The ERS-1 and JERS-1 experiments C-and X-band, IEEE Trans. Geosci. Remote Sens. 37. pp. 2107–2110.
7. Ulaby, F.T., Moore, R.K. and Fung, A.K. 1986. Microwave remote sensing: active and passive, Vol. III, from theory to application. Artech House, Dedham, MA. website:http://hydrolab.arsusda.gov/washita94/wash94.html, Hydrology and Rem. Sensing Lab., USDA, 2002, Accessed in Jan 2004.
8. Yadav ,J.S. and Gandhi, J.M. 1992. Simple microwave technique for measuring the dielectric parameters of solids and their powders. Indian J. of Pure and Appl. Phys, 30, pp. 427–432.

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