Topic
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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TL;DR: In this paper, the current distribution, input impedance, and radiation pattern of wire antennas printed on a dielectric substrate are computed by solving Pocklington's equation by moment methods.
Abstract: Printed dipole antennas find increasing use in microwave as well as far infrared frequencies. The current distribution, input impedance, and radiation pattern are computed for wire antennas printed on a dielectric substrate. The current distribution is obtained by solving Pocklington's equation by moment methods. The Green's function pertinent to the problem involves improper Sommerfeld-type integrals. These integrals are computed by a real-axis integration technique which involves analytical and numerical steps. The effect of surface modes is carefully taken into account.
227 citations
28 Dec 2001
TL;DR: This article focuses on the type of EIT called adaptive current tomography (ACT) in which currents are applied simultaneously to all the electrodes, where a number of current patterns are applied, where each pattern defines the current for each electrode, and the subsequent electrode voltages are measured to generate the data required for image reconstruction.
Abstract: Methods and apparatus for obtaining a representation of the distribution of electrical impedance within a multiphase flow with an electrically continuous or discontinuous principle flow (3) contained within an electrically conductive solid ring electrode (1), comprising providing a plurality of mutually spaced electrical contacts (2) mounted at the outside wall of the ring and electrically contacted with the ring, applying currents or voltages (4) to the ring from the electrical contacts (2), generating a more homogeneous electric field distribution within the material (3), measuring voltage or current (5) distribution along the ring from other electrical contacts (2), relatively intensifying the imaging sensitivity at the central area of the sensing domain using a π/2 angle sensing strategy and reconstructing the representation of the impedance distribution using CG method with an error processing strategy.
227 citations
TL;DR: In this paper, a frequency-selective surface (FSS) with high in-band transmission at high frequency and wideband absorption at low frequency is presented. But the PLC structure is not considered.
Abstract: This communication presents a novel frequency-selective surface (FSS) with high in-band transmission at high frequency and wideband absorption at low frequency. It consists of a resistive sheet and a metallic bandpass FSS separated by a foam spacer. The resistive element is realized by inserting a strip-type parallel $LC$ (PLC) structure into the center of a lumped-resistor-loaded metallic dipole. The PLC resonates at the passband of the bandpass FSS and exhibits an infinite impedance, which splits the resistive dipole into two short sections per the surface current; this setup allows for high in-band transmission at high frequency. Below the resonance frequency, the PLC becomes finite inductive and the entire FSS performs as an absorber with the metallic FSS as a ground plane. The surface current distribution on the resistive element can be controlled at various frequencies via the PLC structure. The wideband absorption and high in-band transmission of the proposed design are verified by both numerical simulation and experimental measurements. The potential extension to polarization-insensitive designs is also discussed.
224 citations
Patent•
25 Apr 2000
TL;DR: In this paper, an automatic circuit that controls a surgical instrument having a pair of bipolar electrodes is described, which consists of means for measuring the current between the pair of electrodes, an impedance detection circuit in electrical communication with the current measuring means, a comparator in electrical communications with the impedance detector, and a controller electrically connected to the comparator.
Abstract: An automatic circuit that controls a surgical instrument having a pair of bipolar electrodes. The circuit comprises means for measuring the current between the pair of electrodes, an impedance detection circuit in electrical communication with the current measuring means, a comparator in electrical communication with the impedance detection circuit and a controller electrically connected to the comparator. The impedance detection circuit calculates the impedance between the electrodes based on the measured current and generates a first signal indicative of the calculated impedance. The comparator processes the first signal and generates an activation signal if the calculated impedance falls within a predetermined range of impedance values and generates a deactivation signal if the calculated impedance exceeds a deactivation threshold. The controller receives the activation and deactivation signals and transmits a first control signal to a radiofrequency energy output stage to activate the electrodes in response to the activation signal and transmits a second control signal to the radiofrequency output stage to deactivate the electrodes in response to the deactivation signal.
224 citations
01 May 1989
TL;DR: In this paper, the relationship between antenna directivity and load effective receiving area is derived, and the role of the load impedance is clarified, where the connection between antenna indirectivity and the load effective receive area is also derived.
Abstract: The field scattered by an antenna contains a component that is the short circuit scattered field normalized by the short circuit current and a second component that is the radiation field normalized by the transmitting current and multiplied by a factor (1- Gamma ). The RCS is the magnitude squared of the difference between two terms, one being the square root of a complex 'structural' cross section, and the other (1- Gamma ) times the square root of a complex 'antenna' cross section. These relationships, and the role of the load impedance are clarified. The connection between antenna directivity and load effective receiving area is also derived. >
222 citations