Experimental observation and statistics of multipath from terrainwith application to overland height finding

Data is presented from an airborne experiment designed to evaluate electromagnetic pulse scattering from a variety of terrain types for the application of overland height finding. The one-way propagation data was collected at ultrahigh frequency (UHF) and very high frequency (VHF) frequencies using a 3-MHz pulsed CW signal with the radars mounted on two aircraft. A statistical analysis of the data shows that the probability of a detectable ground reflection and the strength of that reflection vary as a function of the terrain roughness. We introduce a broad-band synthesis technique in which Fourier theory is used to generate a time-domain response from a CW propagation model. Results from this technique agree well with the experimental observations, but the lack of detailed terrain information does not allow exact reproduction of the fine details     

Electromagnetic scattering calculated from pair distributionfunctions retrieved from planar snow sections

Electromagnetic wave scattering in dense media, such as snow, depends on the three-dimensional (3D) pair distribution function of particle positions. In snow, two-dimensional (2D) stereological data can be obtained by analyzing planar sections. In this paper the authors calculate the volume 3D pair distribution functions from the 2D stereological data by solving Hanisch's integral equation. They first use Monte Carlo simulations for multisize particles to verify the procedure. Next they apply the procedure to available planar snow sections. A log-normal distribution of particle sizes is assumed for the ice grains in snow. To derive multisize pair functions, a least squares fit is used to recover pair functions for particles with sufficient number density and the hole correction approximation is assumed for the larger particles. A family of 3D pair distribution functions are derived. These are then substituted into dense media scattering theory to calculate scattering. It is found that the computed scattering rates are comparable to those calculated under the Percus-Yevick approximation of pair distribution functions of multiple sizes