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.

Cancellation system for frequency reuse in microwave communications

Abstract: Substantial improvements in frequency reuse in microwave communications systems is achieved by canceling co-channel interference and transmitter leakage Interferometric beam-narrowing reduces beamwidth without reducing peak magnitude of the beam pattern Frequency-dependent beam-shaping compensates for frequency-dependent distortions of the beam pattern thereby improving bandwidth A spatial demultiplexing technique utilizes spatial gain distributions of received signals to separate signals, even from co-located transmit sources, and uses microwave lensing to enhance received spatial gain distributions Predetermined cross-polarization interference is used to separate differently-polarized receive signals A reference branch provides a cancellation signal to a receiver to cancel transmitter leakage signals An error signal controls an impedance-compensation circuit that is responsive to changes in antenna impedance but not to receive signals A dc bias magnetic field applied to a magnetic permeable material adjusts non-linear distortion in a cancellation circuit for canceling distortion in a transmitter leakage signal Discreet impedance elements approximate a circuit having distributed impedance

Control of externally induced current in an implantable pulse generator

Abstract: The present invention takes the form of a current limiting apparatus and method for limiting current flow, induced when the level of an external signal is greater than an external signal threshold signal level, in a conductive loop formed by a medical device implanted within a living organism having electrically excitable tissue. The system includes an implantable pulse generator (IPG) system having a housing, a signal generator disposed in the housing that generates an electrical signal, and at least one lead extending from the housing to convey electrical signal to the patient. To limit the induced current flow, the IPG includes current limiting componentry, an impedance increasing element, and/or alternating current blocking elements. These components provide an alternating current impedance path to the electrical ground from a lead coupled to the capacitive element. Also disclosed are techniques for reducing the effective surface area of the current inducing loop caused by the IPG system.

Variable frequency current control device for discharge lamps

Abstract: A control circuit for starting and operating a gas discharge lamp comprising a variable frequency waveform generator coupled to the discharge lamp via a non-resonant coupling network that includes a reactance type ballast impedance. The lamp current is monitored to automatically vary the frequency of the variable frequency generator as a function of the lamp current so as to vary the reactance of the ballast impedance in a sense to regulate or limit the lamp current.

Universal active filter using current conveyors

Abstract: A universal second-order active filter network employing CCII-type current conveyors is reported. The circuit offers wide bandwidth, high input impedance and independent control of ?0, Q and voltage gain with separate grounded resistors. The circuit also uses grounded capacitors and is therefore ideal for integration.