Eliminating common-mode clutter in data is one of the key aspects of road sensing with GPR. Common-mode interference can occur as a result of multipath propagation of an electromagnetic signal when the reflected signal from the same object arrives at the receiver from different directions and with different delays. Similar phenomena also occur when using antennas raised above the surface due to multiple reflections between the air–surface interface and the antenna. These interferences can significantly distort the data received by the GPR and interfere with the accurate determination of the parameters of the roadway. Therefore, the elimination of common-mode clutter is an important task to improve the quality of the obtained results. In this paper, we consider a method for filtering common-mode clutter in the radar data of the multichannel GPR “Terrazond”, which were obtained by sounding a test section of a highway. The results obtained during filtering can then be used to determine the thickness of the pavement layers using approaches that take into account the signal delay determined by the amplitude jump, for example, the common point method or if the permittivity of each layer is known. The obtained thicknesses of pavement layers are compared with the results obtained during core drilling by the Russian Road Research Institute.

This article discusses the possibility of using a metamaterial to focus radiation from an antenna for GPR. Composite ring conductors were used as a material for focusing radiation at frequencies of 0.5–3 GHz. The modeling of the matrix structure is presented, and the electric component of the field is considered when using a four-layer structure with a thickness of about 5 cm. Experimental studies of the focusing properties of the metamaterial and the possibility of its use in ground-penetrating radar are presented. Using the developed system, an object was detected at different depths, and the superiority of the metamaterial in relation to the use of a focusing system based on a parabolic mirror is shown.