| Carbon nanotubes have assumed significant attention due to the wide spectrum of exciting properties they possess. Applications involving the use of carbon nanotubes extend from dc to terahertz frequency range. However, very limited work involving systematic studies of nanotubes has been reported over the microwave frequency range. Single-walled nanotubes (SWNTs) show superior behavior and are therefore the preferred choice when selecting nanotubes. Present work is therefore aimed at studying the high frequency characterization of single-walled carbon nanotubes (SWNTs) over the frequency range of 50 MHz to 12 GHz.;A shielded open-circuited coaxial probe, based on non-resonant technique, was used for broadband frequency analysis of surfactant (Pluronic) stabilized SWNT suspension. Excellent correlation observed for the results obtained from this method and another pair of DRs suggests the validity of our results for these randomly oriented SWNTs. The SWNT and Pluronic conductivity was determined to be 1.6x105 S/m and 6x10-2 S/m, respectively.;A microwave measurement system involving the use of split-post dielectric resonator (SPDR), a variant of the dielectric resonator (DR) technique, was designed, developed, and implemented in this work to probe the tensors of complex permittivity and permeability for anisotropic samples. XY scanning was performed to image the interaction of the electromagnetic field from SPDR with the sample, and cavity perturbation theory was used to extract the material parameters. SWNTs are expected to show different dielectric responses along and perpendicular to their axis because of their unique high aspect ratio geometry. Macroscopic SWNT fiber, comprising of a bunch of well-aligned individual SWNTs, was selected as the sample. Dielectric constants of 19 and 2.76 along and perpendicular to the fiber axis, respectively, were extracted for the SWNT fiber, thus proving their anisotropic behavior. Measurement sensitivity and applicability of electromagnetic field imaging based on DR technique were addressed. |
