Design and implementation of a low cost portable material analyzer

Site-specific wave propagation simulators used for wireless channel characterization have shown promising results in the last decade. However, accuracy of predicted results by such tools relies on their input data about the environment (i.e. geometry and material properties). A low cost and portable/handheld device capable of estimating the material properties of the objects could provide valuable data about the environment for a site-specific simulator. One such device is described in [1]. The idea is to monitor the change in the reflection coefficient of an antenna when holding it against the object of interest and to transfer the measured data to a laptop for post processing and estimation of the objectpsilas material (epsiv_r, sigma) and thickness, as appropriate. When such data is combined with a building database, the geometry can be analyzed to produce a site-specific wireless channel model. Toward this vision, this paper presents the magnitude and phase measurement capability achieved by a system of directional couplers, an IC capable of measuring gain and phase and a ZigBee radio for wireless data transfers between portable material analyzer and a laptop. Its accuracy is verified with a commercial Vector Network Analyzer (VNA).