Improved Propagation Models for Discrete Random Media
Abstract
This report developed an exact spectral-domain formulation for characterizing wave propagation in continuous random media. The formulation consists of a pair of coupled first-order differential equations for waves propagating in the forward and backward directions. These generalized transmission line equations fully accommodate backscatter, and they impose no restriction on scattering angle. In our first application of these equations, the models that are commonly used for propagation of light in the atmosphere and radiowaves in ionized media are generalized to accommodate backscatter. The backscatter enhancement predicted by the cumulative forward scatter single backscatter approximation does not occur unless the finite correlation between the forward and backward propagating waves is included. The model is extended to discrete random media. A similar pair of differential equations is derived that characterize the propagation of vector waves in sparse discrete random media. The equations are exact for small numbers of particles, and can be used to compute the mutual interaction among scattering objects whose free-space scattering characteristics are known. From this model we generalized the effective wave number that is commonly used for coherent wave propagation to include both backscatter and cross polarization terms. When generalized to second order, our equations can be cast in the same form as equations of vector radiative transport, but they are derived directly from Maxwell's equations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1989
- Accession Number
- ADA211085
Entities
People
- C. L. Rino