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An infinite SWR represents complete reflection by a load unable to absorb electrical power, with all the incident power reflected back towards the source. It should be understood that the match of a load to the transmission line is different from the match of a source to the transmission line or the match of a source to the load seen through ...
Properly designed, a bridge circuit can not only indicate a match, but the degree of mismatch – making it possible to calculate the SWR. This usually involves alternately connecting the reference wave and the reflected wave to a power meter, and comparing the magnitudes of the resulting deflections. [1]: 27‑03
where RL(dB) is the return loss in dB, P i is the incident power and P r is the reflected power. Return loss is related to both standing wave ratio (SWR) and reflection coefficient (Γ). Increasing return loss corresponds to lower SWR. Return loss is a measure of how well devices or lines are matched. A match is good if the return loss is high.
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.
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 ...
Reflected power from a badly tuned antenna can present an improper load at the transmitter which can damage it. The SWR meter requires about 5–10 watts of outgoing signal from the radio to register the reflected power (if any), and then only indicates the relative degree of mismatch, not the reactive and resistive impedance seen at the end of ...
The blue circle, centered within the impedance Smith chart, is sometimes called an SWR circle (short for constant standing wave ratio). The complex voltage reflection coefficient Γ {\displaystyle \Gamma \,} is defined as the ratio of the reflected wave to the incident (or forward) wave.
A ratio of 1:1 indicates an impedance match, meaning that the load is completely resistive so all of the power is absorbed and none is reflected. A higher ratio indicates a mismatch and reflected power. The matching network is adjusted until the SWR is below an acceptable limit.