Design and analysis of wideband antennas for borehole and surface ground penetrating radars: Application to soil moisture content measurements

In this paper, we have presented original wide band antenna design associated with a crosshole and a surface GPR configuration dedicated to the dielectric characterization of the subsurface. The antenna geometries defined, usually used for UWB applications at frequencies higher than 3 GHz, have been adapted to work at lower frequencies around 500 MHz to obtain a sufficient penetration depth. Moreover, size constraints have led us to design compact geometries. The overall links in both configurations have been modeled using FDTD simulations and detailed parametric studies have been made to optimize the antenna geometries for our application. First measurements associated with the crosshole radar have allowed to validate the two types of antenna designs proposed. Concerning the surface radar the experimental validation of the antennas developed on a test site is under way.