A free space approach for extracting the equivalent dielectric constants of the walls in buildings

To simulate the wave propagation in buildings for wireless indoor communications, one needs to know the reflection and transmission properties of the building structures. Since those properties depend not only on the constitutive parameters of the buildings but also on the thicknesses of the structures, the determination of the constitutive parameters for different building structures is useful in computer simulations for predicting the indoor propagation. A free-space approach is developed to measure the dielectric constants of the walls in buildings. For indoor propagation modeling, the overall effects of the walls are more important, since large areas of the walls will be illuminated by the incoming waves. Other methods such as open-ended coaxial probes measure the local material properties near the contact points of the probes, and local variations of the properties may have significant influences on the measured results. Therefore, the free-space approach is more suitable for determining the material properties of the compound walls for equivalent dielectric constants by modeling the walls as dielectric slabs with uniform thicknesses and material properties.