Thevenin impedance

To determine V0, we can remove circuit B and calculate the voltage drop across the terminals n and n. This voltage drop is the Thevenin voltage. To determine the impedance ZQ, we can kill all the sources in circuit A, as we did in Figure 2.33, and then calculate the impedance from n-n terminals by looking back into circuit A. This impedance Z0 is the Thevenin impedance, which is also called the output impedance of circuit A. 

An equivalent Thevenin circuit is shown in Fig. 6.72. If VL is the potential difference across the impedance of the load 2EL (e.g. the recorder in the above example), then ... 

Thevenin s theorem states that a section of a linear circuit containing one or more sources and impedances can be replaced with an equivalent circuit model containing only one voltage source and one series-connected impedance, as shown in Figure 2.35. 

It is well known that any receiving antenna can be described by a Thevenin equivalent circuit, shown in Fig. 2.13. Here the power delivered to the load impedance Zl will always correctly represent the power being absorbed by the antenna, while the power being lost in represents power being reradiated somewhere in space by the antenna. However, the antenna may actually scatter considerably more power than is being lost in Za-... 

Fig. 2.13 The Thevenin equivalent circuit for a receiving antenna always yields the correct power delivered to the load impedance Zl. The power lost in the antenna impedance Za represents power scattered somewhere, not necessarily in the back direction. Additional scattering not accounted for by Za will in general take place.

The second scheme is shown in Fig. D.13. Here aU elements are loaded directly with the same load impedances Zi and exposed to an incident plane wave (note no connectors are necessary, strictly speaking). From the Thevenin equivalent circuit shown in the insert we then have... 

J. Thevenin [1985] Passivating Films on Lithium Electrodes. An Approach by Means of Electrode Impedance Spectroscopy, Journal of Power Sources 14, 45-52. 

Thevenin s Theorem is very useful when only voltage and current at a transition (boundary) point between distributed-parameter lines are to be obtained. In Figure 1.40, the impedance seen from nodes 1 and V to the right is Zq, and the voltage across the nodes is V. ... 

When an impedance Z is connected to the nodes, a current I flowing into the impedance is given by Thevenin s Theorem as ... 

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