Microwave Measurement of the Complex Dielectric Tensor of Anisotropic Slab Materials

摘要

A linearly polarized electromagnetic wave incident on an anisotropic material suffers attenuation, phase change, and depolarization upon transmission through or reflection from the material. Here it is shown how the measured electrical properties of a wave transmitted through dimension lumber can be used to determine the complex dielectric tensor. The theory which applies equally to other lossy and anisotropic materials such as man-made composites having a 2 x 2 uniaxial tensor, is couched in terms of the measurable attenuation, phase change, and depolarization. A microwave measurement system has been developed for measuring these parameters. Results are given for extensive experiments conducted at 4.81 GHz on Douglas fir for moisture contents ranging from dry to complete saturation. The technique shows considerable promise as an accurate nondestructive diagnostic tool for evaluating the electrical, and hence, the physical and mechanical properties of semi-transparent anisotropic materials. (ERA citation 09:046533)