Estimation of Electromagnetic Properties in Soil Testbeds Using Frequency and Time Domain Modeling

Contamination of underground systems causes serious detriment of the environment and can pose a serious threat to human health. The challenge of locating many common contaminants creates the need to develop technologies that enhance our ability to detect and characterize underground contamination. Cross-Well Radar (CWR) is being evaluated as a potential technology for detection of hazardous contaminants, such as Dense Non-Aqueous Phase Liquids (DNAPLs), present in underground environments. This paper addresses the development of enabling CWR technologies that rely on the use of transmission and reflection measurements to detect changes in soil electromagnetic (EM) properties caused by the presence of underground target elements, such DNAPL contamination. Time- and frequency-domain measurements and simulations are applied to assess the performance of antennas and design testbeds for proper estimation of EM properties in soil systems. Results indicate that proper development of CWR testbeds must account for wave propagation near sharp EM boundaries. Time-domain analysis shows that s-parameters measurements in a properly developed testbed can be applied to accurately estimate EM properties of bulk soil. The integrated use of soil testbeds with time- and frequency-domain EM modeling, thus, lead to enhanced CWR enabling technologies for DNAPLs detection in underground environments.