Electromagnetic Characterization of White Spruce at Different Moisture Contents using Synthetic Aperture Radar Imaging

摘要

Detection and quantification of moisture content inside wood (timber) is key to ensuring safety and reliability of timber structures. Moisture inside wood attracts insects and fosters the development of fungi to attack the timber, causing significant damages and reducing the load bearing capacity during their design life. The use of non-destructive evaluation (NDE) techniques (e.g.. microwave/radar, ultrasonic, stress wave, and X-ray) for condition assessment of timber structures is a good choice. NDE techniques provide information about the level of deterioration and material properties of timber structures without obstructing their functionality. In this study, microwave/radar NDE technique was selected for the characterization of wood at different moisture contents. A 12 in-by-3.5 in-by.1-.5 in. white spruce specimen (picea glauca) was imaged at different moisture contents using a 10 GHz synthetic aperture radar (SAR) sensor inside an ancchoic chamber. The presence of moisture was found to increase the SAR image amplitude as expected. Additionally, integrated SAR amplitude was found beneficial in modeling the moisture content inside the wood specimen.