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Dielectric loss
About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.
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TL;DR: In this paper, the effect of temperature, frequency and composition on the dielectric behavior and ac electrical conductivity were studied for a series of Zn-substituted Ni-Mg ferrite samples prepared using the usual ceramic technique.
123 citations
TL;DR: The results indicate that the strong microwave absorption property is achieved through a balancing of dielectric loss and magnetic loss, which presents a new strategy for the future design of MAMs.
Abstract: Lightweight, broad-band, and highly efficient microwave-absorbing materials (MAMs) with tunable electromagnetic properties are in high demand. However, the absorption properties are limited by the simple loss mechanism in commonly used absorbing materials. Here, we tested the microwave-absorbing properties of Fe-NiS2/NiS/poly(vinylidene fluoride) (PVDF) in the frequency range of 2-18 GHz. For the 2.5% Fe-NiS2/NiS/PVDF with the filling content of 20 wt %, the maximum reflection loss can reach -61.72 dB at 14.88 GHz, and the bandwidth can reach 3.8 GHz with the reflection loss value below -10 dB. Loss mechanisms of different composites were analyzed on the basis of their magnetic and dielectric properties using both experimental and computational methods. The results indicate that strong microwave absorption property is achieved through a balancing of dielectric loss and magnetic loss. These findings present a new strategy for the future design of MAMs.
123 citations
TL;DR: In this paper, an analytical expression for the energy loss suffered by a fast electron passing near a homogeneous dielectric sphere is derived within a fully relativistic approach, and the variation of the energy-loss spectra with both the radius of the sphere and the impact parameter of the electron trajectory is studied in detail.
Abstract: An analytical expression for the energy loss suffered by a fast electron passing near a homogeneous dielectric sphere is derived within a fully relativistic approach. The sphere is described by a frequency-dependent dielectric function. The electromagnetic field induced by the passage of the electron is then obtained by expressing the solution of Maxwell’s equations for this geometry in terms of the scattering of the multipole expansion of the incoming electromagnetic field at the sphere. The energy loss is derived from the induced field acting back on the electron. The variation of the energy-loss spectra with both the radius of the sphere and the impact parameter of the electron trajectory is studied in detail. Part of the energy loss is transformed into radiation, which is also investigated. For spheres characterized by real dielectric functions, like those of ionic materials in the transparency-frequency region, it is shown that the entire energy loss is transformed into radiation. Examples of loss spectra and radiation emission spectra are given for a material described by a Drude-like dielectric function ~e.g., Al! and for SiO2 . @S0163-1829~99!12103-9#
123 citations
TL;DR: In this article, the authors investigated propagation in dielectric loaded rectangular waveguide for varying slab thickness and dielectrics constant and found that power handling capacities which are double or triple that of standard waveguide are achievable using the dielectoric loaded waveguide.
Abstract: Propagation in dielectric loaded rectangular waveguide is investigated theoretically for varying slab thickness and dielectric constant. The slabs are placed across the center of the waveguide in the E plane. This geometry is found to offer bandwidths in excess of double that of rectangular waveguide for dielectrics having dielectric constants of approximately 18. Power handling capacities which are double or triple that of standard waveguide are achievable using the dielectric loaded waveguide. In addition to the theory, design curves of bandwidth, guide wavelength, cutoff wavelength, impedance, power handling capacity, wall losses, and dielectric losses are presented and compared to experiment where possible.
123 citations
TL;DR: In this paper, the dielectric properties of asphalt pavement were studied in the process of developing a roller mountable microwave asphalt pavement density sensor as part of the National Cooperative Highway Research Program IDEA project.
Abstract: This paper describes dielectric properties of asphalt pavement that were studied in the process of developing a roller mountable microwave asphalt pavement density sensor as part of the National Cooperative Highway Research Program IDEA project. This new sensor involves simultaneously measuring reflected microwave signals from the asphalt pavement in front of and behind the vibratory roller. As the reflected signal and penetration depth of microwaves depend on the dielectric properties of asphalt pavement, temperature, and frequency dependencies of the permittivity and loss of asphalt, samples of different densities were studied in the frequency range from 100 Hz to 12 GHz. Results show that (1) permittivity and loss depend on frequency and temperature; (ii) the higher the pavement density, the higher the permittivity; (iii) permittivity slightly increases with temperature; (iv) moisture strongly increases permittivity and loss at low frequencies and only slightly at microwave frequencies; and (v) the penetration depth of microwaves in asphalt pavement is about 1214 cm at 8 GHz and only about 4 cm at 30 GHz.
123 citations