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In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Often, the desired value is selected to maximize power transfer or minimize signal reflection .
Using the Smith chart, the normalised impedance may be obtained with appreciable accuracy by plotting the point representing the reflection coefficient treating the Smith chart as a polar diagram and then reading its value directly using the characteristic Smith chart scaling. This technique is a graphical alternative to substituting the values ...
In telecommunications and transmission line theory, the reflection coefficient is the ratio of the complex amplitude of the reflected wave to that of the incident wave. The voltage and current at any point along a transmission line can always be resolved into forward and reflected traveling waves given a specified reference impedance Z 0.
The input impedance of an infinite line is equal to the characteristic impedance since the transmitted wave is never reflected back from the end. Equivalently: The characteristic impedance of a line is that impedance which, when terminating an arbitrary length of line at its output, produces an input impedance of equal value. This is so because ...
For impedance matching networks, a better match can be obtained by also setting a minimum loss. That is, the gain never rises to unity at any point. [48] Time-delay networks can be designed by network synthesis with filter-like structures. It is not possible to design a delay network that has a constant delay at all frequencies in a band.
A generator in electrical circuit theory is one of two ideal elements: an ideal voltage source, or an ideal current source. [1] These are two of the fundamental elements in circuit theory. Real electrical generators are most commonly modelled as a non-ideal source consisting of a combination of an ideal source and a resistor.
With no matching unit, Varney specified 75 Ω cable be used at the junction of the ladder line and coax (not 50 Ω); the higher 75 Ω impedance makes a closer match the end of the ladder line. An earth-grounded 4:1 voltage balun may be used to connect the coax to the ladder line, and 1:1 current balun should be used between the coax and the ...
These equations are exact, for all realisable impedance values, unlike image theory where the propagation function only predicts performance accurately when Z S and Z L are the matching characteristic impedances of the network. The equations can be simplified by making a number of assumptions.