The dielectric spectroscopy of Anabaena 7120 protoplast suspensions has been investigated over the frequency range of 40 Hz-110 MHz. The protoplast suspensions showed a complicated dielectric dispersion consisting of at least four distinct sub-dispersions with the increasing frequencies due to the Maxwell-Wagner interfacial polarization. The double-shell model, in which an equivalent shell of t...

The emerging field of communications has increased the demand of electronically tunable reflectarray antennas. Substrate material properties play at1 important role in the design of reflectamy antennas. Variable permittivity materials such as liquid crystals and fenoelectrics have received great deal of attention due to their non-linear material properties. A comparative analysis behveen the pr...

Mechanical details as well as electrical models of FDR (frequency domain reflectometry) sensors for the measurement of the complex dielectric permittivity of porous materials are presented. The sensors are formed from two stainless steel parallel waveguides of various lengths. Using the data from VNA (vector network analyzer) with the connected FDR sensor and selected models of the applied sens...

The temperature behaviour in the range 22-500 °C of the dielectric permittivity in the infrared range is investigated for CaF(2), BaF(2) and Al(2)O(3) through reflectivity measurements. The dielectric permittivity is retrieved by fitting reflectivity spectra with a model taking into account multiphonon contributions. The results extrapolated from the measurements are applied to predict a temper...

We describe a perturbation formulation for the problem of computing electrostatic capacitances of multiple conductors embedded in multiple dielectric materials. Unlike the commonly used equivalent-charge formulation (ECF), this new approach insures that the capacitances are computed accurately even when the permittivity ratios of the dielectric materials are very large. Computational results fr...

The dielectric permittivity, tunability ~De/e!, and loss tangent of Ba12xSrxTiO3 ~BST! films grown by pulsed-laser deposition are studied by near-field microwave microscopy. Based on theoretical simulations, a method is developed to measure the uniaxial dielectric anisotropy, e' /e i , in BST films grown at different oxygen pressures. The measured e' /e i decreases with the film-growth oxygen p...

This work presents a procedure to measure the effective dielectric permittivity in transmission lines. The procedure is based on an improved Frequency Domain Reflectometry (FDR) method. In this technique, the measured reflection coefficient as a function of the frequency is used to synthesize the response of a terminated transmission line to an ideal delta pulse in different finite bandwidths. ...

We report a comparative study of optical properties of 5-20 nm thick pyrolytic carbon (PyC) films, graphite, and graphene. The complex dielectric permittivity of PyC is obtained by measuring polarization-sensitive reflectance and transmittance spectra of the PyC films deposited on silica substrate. The Lorentz-Drude model describes well the general features of the optical properties of PyC from...

We present a simple method to quantitatively image the dielectric permittivity of soft materials at nanoscale using electrostatic force microscopy (EFM) by means of the double pass method. The EFM experiments are based on the measurement of the frequency shifts of the oscillating tip biased at two different voltages. A numerical treatment based on the equivalent charge method allows extracting ...

A nanocapacitor with ultra high capacitance (718 ± 0.2 pF) has been fabricated using electro-deposited Au nanowires manipulated between two Au microelectrodes by the dielectrophoresis technique. A high dc resistance value (∼100 M ) and nonlinear current–voltage characteristics indicate the formation of a dielectric interface between the nanowires. From frequency dependent conductivity, it is se...