title: A Q-Band Free-Space Characterization of Carbon Nanotube Composites.
abstract: We present a free-space measurement technique for non-destructive non-contact electrical and dielectric characterization of nano-carbon composites in the Q-band frequency range of 30 GHz to 50 GHz. The experimental system and error correction model accurately reconstruct the conductivity of composite materials that are either thicker than the wave penetration depth, and therefore exhibit negligible microwave transmission (less than -40 dB), or thinner than the wave penetration depth and, therefore, exhibit significant microwave transmission. This error correction model implements a fixed wave propagation distance between antennas and corrects the complex scattering parameters of the specimen from two references, an air slab having geometrical propagation length equal to that of the specimen under test, and a metallic conductor, such as an aluminum plate. Experimental results were validated by reconstructing the relative dielectric permittivity of known dielectric materials and then used to determine the conductivity of nano-carbon composite laminates. This error correction model can simplify routine characterization of thin conducting laminates to just one measurement of scattering parameters, making the method attractive for research, development, and for quality control in the manufacturing environment.
authors.affiliation: Department of Computer Science and Electrical Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Hassan
authors.affiliation: Materials Science and Engineering Division, Material Measurement Laboratory, NIST, Gaithersburg,0 MD 20899 USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Obrzut
authors.affiliation: Applied Chemicals and Materials Division, Material Measurement Laboratory, NIST, Boulder, CO 80305.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Garboczi
keywords: Microwave metrology; conducting nano-carbon composites; error-correction; free space measurement; non-contact non-destructive measurements