摘要:

Microwave scattering and emission behavior of snow and soil with locally and temporally varying parameters, such as moisture content, surface roughness and subsurface structure, is determined by absorption, surface scattering and volume scattering. Various concepts in either of these regimes have been put forward during recent years. Some of them are well-supported by experimental results. More emphasis has recently been put to investigations of the dielectric properties and its relation to volume scattering. A few highlights of the recent developments in modelling of microwave scatterers, and emission properties of snow and soil are summarized in this presentation and some new investigations are discussed.

ISSN:0920-5071    

DOI:10.1163/156939387X00072

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The purpose of this paper is to review some of the inverse methods in electromagnetics for the reconstruction of one-dimensional permittivity and conductivity profiles using transient or spectral data. Two different categories of inversion schemes, viz., the differential-inverse and integral-inverse algorithms, are discussed, and their relationships to other approaches developed in the fields of quantum mechanics and geophysics are pointed out.

ISSN:0920-5071    

DOI:10.1163/156939387X00081

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A set of radiative wave equations including all four Stokes parameters is derived for vector electromagnetic wave propagation in dense nontenuous media. The derivation is based on the quasi-crystalline approximation with coherent potential on the first moment of the field, and the modified ladder approximation on the second moment of the field. These two approximations are shown to be energetically consistent for dense nontenuous media. To simplify the derivation of the radiative wave equations, the model of small spherical scatterers is used. The derived radiative wave equations assume the same form as the classical radiative transfer equations. However, the relations of the extinction rate, the albedo and the phase matrix to the physical parameters of the media include the effects of dense media and can be different from the classical relations of independent scattering.

ISSN:0920-5071    

DOI:10.1163/156939387X00090

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Mueller matrix and polarization covariance matrix are described for polarimetric radar systems. The clutter is modelled by a layer of random permittivity, described by a three-dimensional correlation function, with variance, and horizontal and vertical correlation lengths. This model is applied, using the wave theory with Born approximations carried to the second order, to find the backscattering elements of the polarimetric matrices. It is found that 8 out of 16 elements of the Mueller matrix are identically zero, corresponding to a covariance matrix with four zero elements. Theoretical predictions are matched with experimental data for vegetation fields.

ISSN:0920-5071    

DOI:10.1163/156939387X00108

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor