Professor Vincent P. Drnevich was recently recognized at Purdue for U.S. Patent No. 7,040,145 issued on May 9, 2006 for "Method and Apparatus for Measuring Density and Water Content of Soil." He is co-inventor with Xiong Yu, a former doctoral student who is now an assistant professor at Case Western Reserve University in Cleveland, Ohio. This is the fourth patent for his work on Time Domain Reflectometry with the previous three for work that was done earlier with Dr. Shafiqul Siddiqui as co-inventor. The early work on this research was sponsored by the Joint Transportation Research Program at Purdue in conjunction with the Indiana Department of Transportation and the Federal Highway Administration. The more recent research was sponsored by the National Science Foundation. Purdue News article.

This current TDR patent is a method and apparatus for measuring dry density and gravimetric water content of soil includes the steps of providing a plurality of spikes adapted to be driven into the soil and driving the spikes into the soil in spaced relationship. An electrical signal is applied to the spikes and a reflected signal is analyzed using time domain reflectometry to determine an apparent dielectric constant and the bulk electrical conductivity of the soil. With these parameters, the dry density and gravimetric water content of the soil can be calculated using a predetermined relationship between apparent dielectric constant, bulk electrical conductivity, dry density and gravimetric water content.