| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 87 === In this thesis, geometrical optics (GO) and physical optics (PO) are applied, and a vector network analyzer is used to measure the complex dielectric constants of the building structures. Those objects include a red masonry brick (BK) wall, reinforced concrete (RC) wall, plywood, and hollow brick wall. Transmission, reflection and physical optics methods are used to analyze single and multiple layers of slab structures. Each layer is modeled as a slab with uniform thickness and homogeneous dielectric properties to obtain the equivalent dielectric constant. The frequencies are between 0.5GHz and 3GHz, and different incident angles and polarizations are tested. In the transmission method, two antennas are employed and positioned at different side of the wall to obtain the direct-path transmission signals for determining the equivalent complex dielectric constant. The time-gating function of the network analyzer (VNA, HP8753B) is applied to obtain those transmission signals. As to the reflection method, two antennas are positioned at the same side, and a metal plate is placed over the other side to reflect the signals. One antenna can also be used to perform the reflection measurements, and cables can be placed over the same side. Those two methods are based on geometrical optics. However, physical optics can be applied to calculate the reflecting and scattering properties of metal plate more exactly and a smaller metal plate may be used to measure the complex dielectric constants of the building structures. The Ray-tracing technique and matrix approach are used to determine the transmitted fields through the layer, so that program executing efficiency, time—domain extracting resolution and calculation accuracy may be satisfied. The dielectric constants determined from those free-space methods can provide the electrical constitutive parameters of the building structures for simulating of wave propagations in and outside buildings.
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