Topic

# Image impedance

About: Image impedance is a research topic. Over the lifetime, 2135 publications have been published within this topic receiving 30979 citations.

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01 Jan 1994

TL;DR: In this paper, the authors present a model for estimating the Impedance of Transmission Lines and the Capacitance of Transformer Lines in the presence of Symmetrical Faults.

Abstract: 1 Basic Concepts 2 Transformers 3 The Synchronous Machine 4 Series Impedance of Transmission Lines 5 Capacitance of Transmission Lines 6 Current and Voltage Relations on a Transmission Line 7 The Admittance Model and Network Calculations 8 The Impedance Model and Network Calculations 9 Power Flow Solutions 10 Symmetrical Faults 11 Symmetrical Components and Sequence Networks 12 Unsymmetrical Faults 13 Economic Operation of Power Systems 14 Zbus Methods in Contingency Analysis 15 State Estimation of Power Systems 16 Power System Stability

2,157 citations

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TL;DR: In this article, the authors considered the problem of matching an arbitrary load impedance to a pure resistance by means of a reactive network and derived necessary and sufficient conditions for the physical realizability of a function of frequency representing the input reflection coefficient of a matching network terminated in a prescribed load impedance.

Abstract: This paper deals with the general problem of matching an arbitrary load impedance to a pure resistance by means of a reactive network. It consists primarily of a systematic study of the origin and nature of the theoretical limitations on the tolerance and bandwidth of match and of their dependence on the characteristics of the given load impedance. Necessary and sufficient conditions are derived for the physical realizability of a function of frequency representing the input reflection coefficient of a matching network terminated in a prescribed load impedance. These conditions of physical realizability are then transformed into a set of integral relations involving the logarithm of the magnitude of the reflection coefficient. Such relations are particularly suitable for the study of the limitations on the bandwidth and tolerance of match. Definite expressions for these quantities are obtained in special cases. The practical problem of approaching the optimum theoretical tolerance by means of a network with a finite number of elements is also considered. Design curves are provided for a particularly simple but very important type of load impedance. In addition, a very convenient method is presented for computing the values of the elements of the resulting matching network.

852 citations

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TL;DR: In this article, a new forbidden region for impedance ratio Z/sub o/Z/sub i/ on the S-plane is proposed as the system stability margin requirement, based on which the impedance specifications of individual loads are established.

Abstract: In a DC distributed power system, the interaction between individually designed power modules/subsystems may cause the instability of the whole system. In a small-signal sense, system level stability is determined by the impedance ratio Z/sub o//Z/sub i/. Here, Z/sub o/ is the output impedance of the source module/subsystem, and Z/sub i/ is the input impedance of the load module/subsystem. As a result, an effective way to prevent system instability is defining impedance specifications for modules/subsystems. This paper briefly summarizes existing works and introduces the authors' contribution in defining impedance specifications. A new forbidden region for impedance ratio Z/sub o//Z/sub i/ on the S-plane is proposed as the system stability margin requirement. Based on this proposed forbidden region, the impedance specifications of individual loads are established. Further, a very practical measurement approach is developed to examine whether or not the system stability margin requirement of the forbidden region is satisfied.

538 citations

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20 Jun 1993

TL;DR: In this paper, a forbidden region for the polar plot of the ratio of impedances at the interface between two cascaded power subsystems is determined, and a method of transforming the forbidden region into a load impedance specification for a given source impedance is developed.

Abstract: By applying the loop gain analysis technique, a forbidden region for the polar plot of the ratio of impedances at the interface between two cascaded power subsystems is determined. A method of transforming the forbidden region into a load impedance specification for a given source impedance is developed. The method assures system stability and minimal performance degradation of the distributed power system, while allowing impedance overlap at the interface. >

504 citations

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18 Oct 2010TL;DR: A software-defined radio (SDR) receiver with baseband programmable RF bandpass filter (BPF) and complex impedance match is presented and 8-phase mixing is shown to provide significant benefits such as impedance matching range, rejection of blockers at LO harmonics, and lower noise figure.

Abstract: A software-defined radio (SDR) receiver with baseband programmable RF bandpass filter (BPF) and complex impedance match is presented. The passive mixer-first architecture used here allows the impedance characteristics of the receiver's baseband circuits to be translated to the RF port of the receiver. Tuning the resistance at the baseband port allows for a real impedance match to the antenna. The addition of "complex feedback" between I and Q paths allows for matching to the imaginary component of the antenna impedance. By implementing both real and imaginary components with resistors in feedback around low noise baseband amplifiers, noise figure is also kept low. Tunable sampling capacitors on the baseband side of the passive mixer translate to tunable-Q filters on the RF port which allow for very good out-of-band linearity. Furthermore, the concept of in-band and out-of-band must be redefined as the impedance match and BPF center frequency move with the LO frequency, such that matching and filtering track the receive frequency. Additionally, 8-phase mixing is shown to provide significant benefits such as impedance matching range, rejection of blockers at LO harmonics, and lower noise figure (NF). Measurements from the receiver implemented in 65 nm CMOS show 70 dB of gain, NF as low as 3 dB, and 25 dBm out-of-band IIP3. Furthermore, tunable impedance matching shows that S11 <;- 30 dB can be achieved at any receive frequency from 0.1-1.3 GHz.

410 citations