“Unlocking” the Ground: Increasing the Detectability of Buried Objects by Depositing Passive Superstrates

Abstract

One of the main problems when trying to detect the position and other characteristics of a small inclusion into lossy Earth via external measurements is the object's poor scattering response due to attenuation. Hence, increasing the scattered power generated by the inclusion when using not an active but a passive material is of great interest. To this direction, we examine a procedure of “unlocking” the ground by depositing a thin passive layer of conventional material atop of it. The first step is to significantly enhance the transmission into a lossy half-space, in the absence of the inclusion, by covering it with a passive slab. The redistribution of the fields into the slab and the infinite half-space, due to the interplay of waves between the interfaces, makes it possible to determine the thickness and permittivity of an optimal layer. The full boundary value problem (including the inclusion and the deposited superstrate) is solved semianalytically via integral equation techniques. Then, the scattered power of the buried inclusion is compared to the corresponding quantity when no additional layer is present. We report a substantial improvement in the detectability of the inclusion for several types of ground and burying depths by using conventional lossy materials. Implementation aspects in potential applications as well as possible future generalizations are also discussed. The developed technique may constitute an effective “configuration (structural) preprocessing” which may be used as a first step in the analysis of related problems before the application of an inverse scattering algorithm concerning the efficient processing of the scattering data.