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The power standing wave ratio (PSWR) is defined as the square of the VSWR, [3] however, this deprecated term has no direct physical relation to power actually involved in transmission. SWR is usually measured using a dedicated instrument called an SWR meter .
An SWR meter does not measure the actual impedance of a load (the resistance and reactance), but only the mismatch ratio. To measure the actual impedance requires an antenna analyzer or other similar RF measuring device. For accurate readings, the SWR meter itself must also match the line's impedance (typically 50 or 75 Ohms).
The blue circle, centred within the chart, is sometimes called an SWR circle (short for constant standing wave ratio). The characteristic impedance of a transmission line is the ratio of the amplitude of a single voltage wave to its current wave. Since most transmission lines also have a reflected wave, the characteristic impedance is generally ...
The voltage standing wave ratio (VSWR) at a port, represented by the lower case 's', is a similar measure of port match to return loss but is a scalar linear quantity, the ratio of the standing wave maximum voltage to the standing wave minimum voltage.
The impedance match between the feedline and antenna is measured by a parameter called the standing wave ratio (SWR) on the feedline. Consider a half-wave dipole designed to work with signals with wavelength 1 m, meaning the antenna would be approximately 50 cm from tip to tip.
An impedance mismatch can be also quantified with the standing wave ratio (SWR or VSWR for voltage), which is connected to the impedance ratio and reflection coefficient by: = | | | | = + | | | |, where | | / are the minimum and maximum values of the voltage absolute value, and the VSWR is the voltage standing wave ratio, which value of 1 ...
Input port will mean the input port of the two-port. Output port will mean the output port of the two-port. Symmetric means a case where the source and load have equal impedance. Loss means the ratio of power entering the input port of the pad divided by the power absorbed by the load.
Standing wave ratio (SWR or VSWR) is a basic parameter and the one most commonly measured on a slotted line. This quantity is of particular importance for transmitter antennae. A high SWR indicates a poor match between the feed line and the antenna, which increases wasted power, can cause damage to components in the transmission path, possibly ...