Effect Of Dielectric Substrate Research Articles

Effects of Dielectric Substrates and Ground Planes on Resonance Frequency of Archimedean Spirals.

Superconducting self-resonant spiral structures are of current interest for applications both in metamaterials and as probe coils for nuclear magnetic resonance (NMR) spectroscopy for high-sensitivity chemical analysis. Accurate spiral models are available in the literature for behavior of a spiral below and up to self-resonance. However, knowledge of the higher modes is also important. We present the relationships between the spiral parameters and the multiple mode frequencies of single sided spirals on dielectric substrates as modeled by method of moments simulation. In the absence of a ground plane, we find that the mode frequency has a linear though not necessarily harmonic dependence on the mode number. The effect of a thick substrate can be approximated by an effective dielectric constant. But when the thickness is less than 20% of the spiral trace width (router - rinner) this approximation is no longer accurate. We have developed a simple empirical formula to predict the higher modes.

Intrinsic Electron Mobility Exceeding 103 cm2/(V s) in Multilayer InSe FETs

Graphene-like two-dimensional (2D) materials not only are interesting for their exotic electronic structure and fundamental electronic transport or optical properties but also hold promises for device miniaturization down to atomic thickness. As one material belonging to this category, InSe, a III-VI semiconductor, not only is a promising candidate for optoelectronic devices but also has potential for ultrathin field effect transistor (FET) with high mobility transport. In this work, various substrates such as PMMA, bare silicon oxide, passivated silicon oxide, and silicon nitride were used to fabricate multilayer InSe FET devices. Through back gating and Hall measurement in four-probe configuration, the device's field effect mobility and intrinsic Hall mobility were extracted at various temperatures to study the material's intrinsic transport behavior and the effect of dielectric substrate. The sample's field effect and Hall mobilities over the range of 20-300 K fall in the range of 0.1-2.0 × 10(3) cm(2)/(V s), which are comparable or better than the state of the art FETs made of widely studied 2D transition metal dichalcogenides.

Effect of a dielectric substrate with a subwavelength thickness on light diffraction by rectangular hole arrays on metallic film

A theoretical study of the effect of ultrathin dielectric substrate in THz wave diffraction phenomena on a subwavelength nanostructured system is conducted. The proposed system is composed of a dielectric substrate with a thickness of ∼ λ/1000 and a subwavelength-scaled rectangular hole array on a metal thin film in THz wavelength region. A modified Rayleigh diffraction theory has been developed to take into account the contribution of reflection at the air-substrate interface. A calculation of the terahertz transmission while varying the thickness shows that the effect of a thin dielectric substrate starts to vanish when the thickness becomes ∼1/100 of the incident light’s wavelength. Theoretically, the results are well explained because most electric fields are confined near the rectangular aperture, which results in the dominant existence of the field inside the thin substrate. Additionally, the effect of a thin dispersive substrate is discussed.

Dielectric substrate effect on the metamaterial resonances in terahertz frequency range

We report on the effect of dielectric substrate on the resonance shift of metallic metamaterials operating in the terahertz frequency region. The resonance frequencies for various metamaterials obtained by time-domain spectroscopy agree well with calculations based on the finite-difference time-domain method. The dependencies of the resonance frequency to substrate index are studied, and are systematically determined by introducing an effective substrate index. The relative contributions of the substrate index for various metamaterials are obtained by fitting the numerically obtained effective refractive indices as a function of substrate index, which is found to be ∼0.63 regardless of the metamaterial geometry.

Transmission and scattering on interconnects with via structures

Multivia interconnect structures for printed circuit boards (PCBs) have been analyzed by decomposing the geometry into exterior and interior structures. In this paper, we include the effects of dielectric substrates in the exterior structure. The exterior problem is solved by using the method of moments (MoM). The impedance-matrix elements are evaluated by using a fast method of calculating the layered-medium Green's function. The RWG basis functions are also utilized. Combined with the Foldy–Lax equation for solving the interior structure of a cylindrical vias problem, we analyze the transmission and scattering characteristics of interconnects with via structures. The numerical results of the scattering matrix are obtained for various via structures with a through-hole via and a single-layered via. The results obtained using commercial modeling tools such as HFSS and IE3D are also compared. The differential signaling of common and differential modes of coupled interconnects are illustrated. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 446–452, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21013

Effect of substrate on the efficiency of an arbitrarily shaped microstrip patch antenna

A general approach is presented for the determination of power radiated via the space wave and surface wave from the aperture of an arbitrarily shaped microstrip antenna. The magnetic current model is used for this, and the analysis is carried out in the Fourier domain to determine the effect of the substrate. It has been shown that, in the Fourier domain, the longitudinal components of electric and magnetic displacement vectors follow the transmission line equation and can be solved by inspection. An expression for total radiated power has been derived. The singularities of the integral for power radiation indicate the presence of surface wave modes, and the associated power has been obtained using a singularity extraction technique. The effect of the substrate on space wave power has also been determined. This theory has been applied to a rectangular patch antenna. The results are in conformity with those reported in the literature. It has been found that for the frequency range ( h/\lambda, ), the effect of dielectric substrate can be neglected.