The paper deals with a study of diffraction on dielectric wedge (building corner) in millimeter frequency band, both theoretically and experimentally, to provide knowledge support for ray tracing/launching calculations of MWS interference issues in urban areas. The main motivation was to find balance between reasonably reliable results and necessary demands on calculation complexity and input d...

The effective dielectric constant of the top grounded coplanar waveguide with a liquid crystal (LC) superstrate for phase shifting applications is investigated in the frequency range of 30–60 GHz. Two nematic LC mixtures, namely E7 and MDA-00-3506, are used as the superstrate. The measurements show that MDA-00-3506 offers higher values of phase shift per millimeter than its E7 counterpart. In p...

Surface oxidation and porosity variation play significant roles in the dielectric performance of porous silicon (PS) yet discriminating the contribution of these events is a challenge. Here we present an analytical solution that covers contributions from the components of silicon oxide surface, silicon backbone and voids using a serial–parallel capacitance structure. Agreement between modeling ...

Unlike silicon and traditional III-V semiconductors, the III-nitrides exhibit high spontaneous and piezoelectric polarization charges at epitaxial polar heterojunctions. In the process of investigating scaling properties of gate-stacks consisting atomic-layer deposited Al2O3/III-Nitride heterojunctions, we find interface charges that appear closely linked to the polarization charges of the unde...

Ultra-low-noise microwave oscillators are often required to serve as reference signals in precision phase modulation (PM) noise measurement systems and in a host of other applications. We have significantly improved the spectral purity of NIST’s traditional cavity-stabilized microwave oscillator design, which uses a conventional air-dielectric cavity resonator as a frequency discriminator. We d...

Transmission ellipsometry measures the real and imaginary parts of the ratio τ = t(p)/t(s), where t(s), and t(s) are the transmission amplitudes for thep and s polarizations. For a homogeneous layer, the unknowns to be determined are the layer dielectric constant ε = n(2) and the layer thickness Δz. For nonabsorbing films the thickness can be eliminated, and an algebraic equation for e results....

In 1984 Decker et al.' reported the measurement of thermal conductivity for freestanding thin films of Si02 and A1203. Values were found to be one to two orders of magnitude lower than those for the corresponding bulk materials. The authors attributed this difference to the unique microstructure of dielectric thin films (primarily columnar for vapor-deposited coatingsz), which, along with defec...

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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 ...