Dielectric loss

About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.

Dielectric plug-loaded two-port transmission line measurement technique for dielectric property characterization of granular and liquid materials

Abstract: There are numerous dielectric property characterization techniques available in the microwave regime each with its own uniqueness, advantages and disadvantages. The two-port completely-filled waveguide (transmission line) technique is a robust measurement approach which is well suited for solid dielectric materials. In this case, the dielectric material can be relatively easily machined to fit inside the waveguide and the subsequent measurement of the scattering parameters of this two-port device renders the dielectric properties of the material filling the waveguide. However, this technique is not well suited for measuring the dielectric properties of granular and liquid materials. These materials are used in the production of various composites which are increasingly replacing the use of metals in many environments. If this technique is directly applied to these types of materials, several approximations either in the measurement apparatus or the formulation must be made. To overcome this problem, this paper describes a modification to this measurement technique utilizing two dielectric plugs which are used to house the granular or the liquid dielectric material. In this approach no approximation to the measurement apparatus is made while the presence of the plugs are fully accounted for in the derivations. Using this technique, the dielectric properties of cement powder, corn oil, antifreeze solution and tap water, constituting low- and high-loss dielectric materials (granular and liquid) were measured. In addition, the important issue of measurement uncertainty associated with this technique is also fully addressed. The issue of optimal choice of various measurement parameters is also discussed as it relates to the measurement uncertainty.

High-Speed Computation of Single and Coupled Microstrip Parameters Including Dispersion, High-Order Modes, Loss and Finite Strip Thickness

Abstract: Based on an optimized rigorous hybrid mode solution for covered/open zero thickness microstrip patterns the following frequency dependent single and coupled line data are evaluated with very short CP-times: The characteristic impedances of the even and odd quasi-TEM modes, the propagation/attenuation constants and associated strip current density components of these and the higher order modes, the loss of the dominant modes under consideration of nonuniform strip current, substrate surface roughness and dielectric loss tangent. Finite strip thickness is introduced by a correction of the strip width input values.

Dielectric relaxation in polymeric solids Part 1. A new model for the interpretation of the shape of the dielectric relaxation function

Abstract: A model is proposed which explains the shape of the dielectric relaxation function at the glass transition of polymers. The model is based on the idea that the molecular mobility at the glass transition is controlled by intra- and intermolecular interaction. In addition, a specific model for the local chain dynamics in amorphous polymer systems is used. According to the scaling hypothesis of molecular dynamics the model relates the high frequency dependence of the dielectric loss curve to the local chain dynamics and the low frequency dependence to the intermolecular correlation.

Dielectric ceramic composition

Abstract: PURPOSE:To obtain a dielectric ceramic composition allowing reduced sorts of additives, achieving a high dielectric constant and a low dielectric loss, each of which has an extremely small voltage dependence and deterioration with time by adding a specified wt.% of Mn-based compound to a main composition consisting of SrTiO3, Bi2O3, and TiO2 as an additive. CONSTITUTION:A dielectric ceramic composition consists of 100wt.% a main composition consisting of 50.0-90.5wt.% SrTiO3, 2.0-29.5wt.% Bi2O3, and 5.6-20.5wt.% TiO2 to which a sort of Mn-based compound is added by 0.05-0.20wt.%. A dielectric ceramic composition obtained by molding and baking this composition achieve a high dielectric constant and a low loss, and the voltage dependence and time change of these properties are extremely reduced.

High-Temperature Dielectrics in the BiScO3–BaTiO3–(K1/2Bi1/2)TiO3 Ternary System

Abstract: Perovskite solid solution in the (1−x)[0.4BiScO3–0.6BaTiO3]+x (K1/2Bi1/2)TiO3 [BSBT–KBTx] system was synthesized using conventional sintering and hot-isostatic pressing. Dielectric properties of BSBT ceramics with different dopant levels of KBT were characterized as a function of temperature and frequency for potential use of high-temperature capacitors. The BSBT ceramics with KBT exhibited high dielectric permittivities (ɛr) (>1700 at RT) and low dielectric loss over the temperature range from 100° to 300°C, with flat temperature coefficients of permittivity (TCɛs). In addition, BSBT ceramics with increasing KBT were observed to possess dielectric relaxation characteristics at temperatures (>RT) as observed in lead-based relaxors. Furthermore, high energy densities, being on the order of 4.0 J/cm3 at 220 kV/cm was observed for the BSBT–KBT20 ceramics from the electric-field polarization behavior.