Automation of Advanced Scanners for RF Metrology

Abstract

The characterization of the constitutive properties of materials is an important step in the development of modern RF devices, especially at mm-wave frequencies or in systems that incorporate materials whose performance varies with frequency or the angle of the impinging electrical eld. This thesis discusses the implementation of three material characterization systems designed by the Phased Array Antenna Research and Development (PAARD) group at the Advanced Radar Research Center (ARRC) for taking material measurements under di erent test con gurations. For each system, the majority of the work done was in creating a graphic user interface (GUI) in Labview that would facilitate rapid measurements by providing an intuitive control software for the user. The three systems work for a variety of di erent applications: an S-band waveguide setup for measuring isotropic materials, a C-band three-probe free-space system for measuring anisotropic materials, and a W-band free-space system. All three systems utilize the Nicolson-Ross-Weir (NRW) or Smith algorithm for material parameter extraction. Various other methods exist for material characterization but the NRW method provides relatively precise measurements over a broad band with minimal computational requirements. The importance of material parameters and the de nitions of isotropy/anisotropy will be discussed rst, followed by the method through which the material parameters are calculated. After this the speci cations for each system that was developed are discussed including the physical test setup, the algorithm(s) that are used, the formation of the control software, the calibration techniques used, and the results of material tests.