Materials Measurement Phil Bartley Shelley Begley

NRL (Naval Research Lab) ArchTo Port 1 ofnetworkanalyzerTo Port 2 ofnetworkanalyzerαMeasure s 21 with the network analyzerNRL arch is used usually to measure absorbingmaterials. For absorbers is desired to know thefrequency response of reflectivity at a given angle.Another free-space measurement of interest is reflectivity. It is often desiredto know the reflectivity at a given angle. The material of interest may be anabsorber as illustrated of a material intended to be applied to a metalsurface.Reflectivity measurements are often performed on a NRL (Naval ResearchLaboratory) Arch. The arch allows the user to adjust the angle of theantennas being used while maintaining a constant distance to the sample.The material being measured is placed on the table. Prior to making ameasurement the system is calibrated. The most commonly used calibrationis an isolation-response cal. Time-domain gates are often employed toeliminate unwanted transmission paths.75