Investigation of bistatic scattering using numerical techniques and novel near -field measurements.

Abstract

Currently there exists a desire to pursue novel measurement, numerical, and analytical techniques for characterization of bistatic response of point and distributed targets. This thesis strives to incorporate aspects from each of these electromagnetic (EM) strategies and to apply these techniques to further the understanding of remote sensing of point and distributed targets through bistatic measurements and theoretical scattering models. A planar near-field scanning system is proposed, built, and tested that performs bistatic scattering measurements from both point and distributed targets with a high degree of accuracy. Also, numerical techniques are pursued for advancing the knowledge of EM scattering from rough surfaces using computational electromagnetics by looking at the two major limiting factors of such analysis-time and memory requirements. Through the use of wavelet basis functions, it is found that the moment matrix of the Method of Moments can be made significantly sparse (up to 99% sparse) when a threshold is applied. Efficient sparse matrix solvers now can be used without sacrificing accuracy of the scattering pattern. Using an Iterative Physical Optics approach allows significant time reduction in analysis for 1-Dimensional and 2-Dimensional random rough Perfectly Electrically Conducting (PEC) or impedance boundary surfaces with physical characteristics that have a root mean square (rms) slope less than 0.5. Finally, the performance of a parasitic GPS multi-static radar system is investigated. A feasibility study is conducted with the desire of applying such a system to the remote sensing of the earth without launching high cost satellites, but rather using existing satellites already in orbit. The results of this feasibility study concluded that current GPS satellites do not transmit enough power to accurately measure incoherent bistatic scattering from the earth, but the next generation GPS satellites may be more applicable to this endeavor.