9409890 Han The objective of this program is to develop an improved data interpretation algorithm for the synthetic aperture imaging technique. A composite scheme for retrieving the host medium property is integrated into the coherent focusing algorithm for buried object imaging. The final goal is to establish a general yet reliable microwave imaging system that can be used for inspecting targets embedded in stratified random media. Applications to ground-penetrating operations and nondestructive evaluation of civil engineering structures are addressed. Under this system, data carrying information on the property of the host medium and that of embedded targets will be acquired concurrently but processed separately. A two-stage date processing scheme is designed to achieve this purpose. First, the distinction between the spatial spectra of signals produced by localized targets and that by stratified structures will be used as the mechanism for isolating the signal from the host medium. Then, the extracted information on the host material will be used in the imaging algorithm to provide the correct phase compensation for signals from the targets. The following studies are included: (i) surface echo isolation, (ii) subsurface profile inversion, (iii) model application to signal and noise prediction, (iv) development of imaging algorithm, (v) construction of target detection scheme, and (vi) experiments. ***
