Characterization of dielectric constant of masonry wall using synthetic aperture radar imaging

Masonry structures are widely used for their low cost, durability, fire-resistance, sound isolation and other properties in civil engineering and architecture. Inspection of masonry structures is vital for maintaining their structural performance and long-term safety. Many traditional inspection technologies (e.g., acoustic/ultrasonic, thermographic, electromagnetic) have been applied for the structure health monitoring of masonry structures. The objective of this paper is to apply a synthetic aperture radar (SAR) system for characterizing the dielectric constant of masonry specimens. A 10-GHz imaging radar system was used. A masonry wall was selected, and five ranges (150 cm, 250 cm, 500 cm, 1000 cm and 1500 cm) were considered in collecting SAR images of the masonry wall. From our result, it was found that attenuation of integrated SAR amplitude exhibits a nonlinear pattern as a function of range. An algorithm was developed to estimate the dielectric constant of the masonry wall. Field collected SAR images were compared with a portable 1.6-GHz ground penetrating radar (GPR) system. It was demonstrated that SAR images can be used to estimate dielectric constant of masonry structures in the field.