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L networks for narrowband matching a source or load impedance Z to a transmission line with characteristic impedance Z 0. X and B may each be either positive (inductor) or negative (capacitor). If Z / Z 0 is inside the 1+jx circle on the Smith chart (i.e. if Re( Z / Z 0 )>1), network (a) can be used; otherwise network (b) can be used.
To match the termination at 800 MHz, a series capacitor of 2.6 pF must be placed in series with the transmission line at a distance of 29.6 mm from the termination. An alternative shunt match could be calculated after performing a Smith chart transformation from normalised impedance to normalised admittance.
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 ...
An L-network is the simplest circuit that will achieve the desired transformation; for any one given antenna and frequency, once a circuit is selected from the eight possible configurations (of which six are shown above) only one set of component values will match the in impedance to the out impedance. In contrast, the circuits described below ...
The quarter wave transformer is an alternative to a stub; but, whereas a stub is terminated in a short (or open) circuit and the length is chosen so as to produce the required impedance transformation, the λ/4 transformer is in series with the load and its length and characteristic impedance are designed to produce the required impedance ...
Mismatch loss in transmission line theory is the amount of power expressed in decibels that will not be available on the output due to impedance mismatches and signal reflections. A transmission line that is properly terminated, that is, terminated with the same impedance as that of the characteristic impedance of the transmission line, will ...
An actual wide-band L pad used to match 50 ohms to 75 ohms. An L pad is a network composed of two impedances that typically resemble the letter capital "L" when drawn on a schematic circuit diagram. It is commonly used for attenuation and for impedance matching.
A time-domain reflectometer; an instrument used to locate the position of faults on lines from the time taken for a reflected wave to return from the discontinuity.. A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line, or if ...