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Diameter Estimation of Cylindrical Metal Bar Using Wideband Dual-Polarized Ground-Penetrating Radar

Hai-Han SunWeixia ChengZheng Fan
Dec 2022
Ground-penetrating radar (GPR) has been an effective technology for locatingmetal bars in civil engineering structures. However, the accurate sizing ofsubsurface metal bars of small diameters remains a challenging problem for theexisting reflection pattern-based method due to the limited resolution of GPR.To address the issue, we propose a reflection power-based method by exploringthe relationship between the bar diameter and the maximum power of the barreflected signal obtained by a wideband dual-polarized GPR, which circumventsthe resolution limit of the existing pattern-based method. In the proposedmethod, the theoretical relationship between the bar diameter and the powerratio of the bar reflected signals acquired by perpendicular and parallelpolarized antennas is established via the inherent scattering width of themetal bar and the wideband spectrum of the bar reflected signal. Based on thetheoretical relationship, the bar diameter can be estimated using the obtainedpower ratio in a GPR survey. Simulations and experiments have been conductedwith different GPR frequency spectra, subsurface mediums, and metal bars ofvarious diameters and depths to demonstrate the efficacy of the method.Experimental results show that the method achieves high sizing accuracy witherrors of less than 10% in different scenarios. With its simple operation andhigh accuracy, the method can be implemented in real-time in situ examinationof subsurface metal bars.