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Electrical impedance

About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.


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Journal ArticleDOI
TL;DR: In this paper, a macroscopic theory is developed to describe the motion of the mobile charge carriers (ionic defects) which exist in AgBr at elevated temperatures, which contain the effects of conduction and diffusion currents, space charge, and formation and recombination.
Abstract: Alternating current impedance measurements on samples of silver bromide with silver and with gold electrodes show the presence of polarization effects. These effects appear as a capacitive component of the impedance and a slight dependence of the resistance on the frequency of the measurement, and their dependence on temperature, frequency, pressure, voltage, and impurity content has been investigated. A macroscopic theory is developed to describe the motion of the mobile charge carriers (ionic defects) which exist in AgBr at elevated temperatures. The general equations contain the effects of conduction and diffusion currents, space charge, and formation and recombination. Since these equations are nonlinear, an approximation procedure is developed, which is valid for small values of the applied voltage. The results of the theory with appropriate boundary conditions give semiquantitative agreement with the temperature and frequency dependence of the observed results and afford a good qualitative descripti...

172 citations

Journal ArticleDOI
TL;DR: In this paper, a lumped-element Josephson parametric amplifier with strong coupling to the environment is presented, which allows for frequency dependent variation of the external impedance at a given frequency.
Abstract: We present a lumped-element Josephson parametric amplifier designed to operate with strong coupling to the environment. In this regime, we observe broadband frequency dependent amplification with multi-peaked gain profiles. We account for this behavior using the “pumpistor” model which allows for frequency dependent variation of the external impedance. Using this understanding, we demonstrate control over the complexity of gain profiles through added variation in the environment impedance at a given frequency. With strong coupling to a suitable external impedance, we observe a significant increase in dynamic range, and large amplification bandwidth up to 700 MHz giving near quantum-limited performance.

171 citations

Journal ArticleDOI
H.J. Riblet1
TL;DR: In this article, the authors presented the general synthesis of a radio frequency impedance transformer of n quarter-wave steps, given an insertion loss function of permissible form, for maximally flat and Tchebycheff performance.
Abstract: This paper presents the general synthesis of a radio frequency impedance transformer of n quarter-wave steps, given an "insertion loss function" of permissible form. This procedure parallels that of Darlington for lumped constant filters by providing the connection between Collin's canonical form for the insertion loss function and Richards' demonstration that a reactance function may always be realized as a cascade of equal length impedance transformers terminated in either a short or open circuit. In particular, it is shown that insertion loss functions of the form selected by Collin are always realizable with positive characteristic impedances, and that the synthesis procedure, for maximally flat and Tchebycheff performance, involves the solution, at most, of quadratic equations. In addition, this procedure permits the proof of Collin's conjecture that, for his insertion loss function, the resulting reflection coefficients are symmetrical. Finally, closed expressions are given for the coefficients of the input impedance of a given n section transformer in terms of the n characteristic impedances and vice versa.

171 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a new impedance spectrometer based on the four-point measurement method and offers a measurement range from 1 mHz to 45 kHz with a phase accuracy better than 0.1 mrad.
Abstract: Spectral impedance measurements are receiving increased attention with regard to the characterization of soils, sediments and rocks, particularly in terms of the internal rock structure, the mineralogical composition and the chemistry of fluids contained in porous rocks. In fluid-saturated, porous sedimentary rocks, which are of particular relevance for many hydrological and environmental problems, the polarization processes that give rise to an observed phase shift between input current and output voltage signals are caused by the interaction of the electrolyte in the pores of the rock with electrically charged mineral surfaces. However, this phase response is relatively weak, typically smaller than 10 mrad and sometimes even of the order of only 1 mrad. In order to reliably measure such phase responses in the relevant frequency range, a high-accuracy impedance spectrometer is required. This system must allow phase measurements between 1 mHz and 1 kHz with a phase accuracy better than 0.1 mrad. In this paper, we present a new impedance spectrometer which meets these requirements. It is based on the four-point measurement method and offers a measurement range from 1 mHz to 45 kHz. Furthermore, we present design information for the sample holder and the electrodes, and methods for performing numerical corrections to reduce measurement errors. The overall accuracy of the setup was validated using water and sand with well-defined polarizable objects.

170 citations

Journal ArticleDOI
TL;DR: In this article, an infinite array of arbitrarily oriented identical elements with arbitrary identical currents is considered, and the mutual impedance between the array elements and an exterior arbitrarily oriented element is derived, particularly useful when the array is located adjacent to a dielectric interface.
Abstract: An infinite array of arbitrarily oriented identical elements with arbitrary identical currents is considered. The field from this array is expanded into plane inhomogeneous waves, and the mutual impedance between the array elements and an exterior arbitrarily oriented element is derived. The formulation is particularly useful when the array is located adjacent to a dielectric interface. Numerical examples are given and the relationship to earlier formulations pointed out. It is further shown that the impedance of a single element can be obtained as the average of the scan impedance taken over the entire hemisphere (called the array scanning method (ASM)). This technique has a clear physical interpretation which greatly facilitates its uses, which include the moment method solutions of wire antennas as applied to the Sommerfeld integral. Numerical evaluation is straightforward when the dipole is in the lossy half-space, and the utility of the method is demonstrated by the presentation of results for the input impedance of dipoles in a variety of half-space environments. Solution is by Galerkin's method with a piecewise sinusoidal expansion for the current. Computer time is proportional to d^{-1} , where d is the distance of the dipole to the interface. For conducting media and low frequencies an approximation is made to reduce computation time. The moment method solution of a dipole buried at a depth as small as 1/150000 wavelength in the earth is presented.

170 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,514
20223,479
20211,009
20201,579
20191,924
20181,809