Irregular changes in antenna height during high speed scanning as a source of essential errors in measuring the thickness of asphalt

The use of ground-based radar (GPR) to scan the subsurface pavement structure allows to diagnose the road surface, determine the thickness of pavement layers, assess the existence of structural disturbances under the road surface, and so on. Network scale GPR scanning are performed at high speed using an air-coupled (horn) antennae in order to avoid interference with traffic. The requirement of the regulator for measurements on highways at high speed contradicts the need for high-quality data collection, which causes errors in determining the thickness of the asphalt. One of the reasons for such error is the irregular changes in antenna height during the scanning at high speed. This article discusses the range of this error and shows that the accuracy of asphalt thickness measurement depends not only on the antenna height, but also on the value of dielectric permittivity and signal scattering at the reference point.