Summary of return loss and VSWR Loss and VSWR

Summary of return loss and standing wave ratio


Following excerpt from: http://www.soontai.com/cal_rtvswr.html


RL = 20log ((vswr+1)/(VSWR-1)) VSWR = (1+ (10^RL/20))/((10^RL/20)-1)

* RL = Return Loss

Return Loss:
This is the DB value of absolute reflection coefficient.
It is rather curious concept of transmission engineering.
This loss value becomes 0 for 100% reflection and becomes infinite for
An ideal connection.

Voltage Standing Wave Ratio (VSWR):
This is the ratio of maxmum voltage to minimum voltage
In standing wave pattern.
It varies from +1 to infinite.


following excerpt from: http://www.mscbsc.com/askpro/question87979

Return loss RL

It is the reciprocal of the reflection coefficient, expressed in decibels.

The value of RL between 0dB to infinity, the smaller the return loss means that the match is worse, conversely, the better the match.

The 0dB represents full reflection, and infinity represents an exact match.

In mobile communication, the return loss is generally more than 14dB (corresponding to vswr=1.5).

RL=10LG (Incident power/reflected power)

Standing wave ratio VSWR= (1+ reflection coefficient)/(1-reflection coefficient), reflection coefficient = reflected wave amplitude/incident amplitude.

If the feeder connector is good: The reflection coefficient is 0 (no reflection), if the joint worst reflection coefficient is 1 (the above can be seen from the reflection coefficient of the formula)

So the larger the VSWR range =1~∞,VSWR This value, the connection is not good at the connector.

Standing wave is generally less than 1.5, in terms of the feeder, standing wave is generally less than 1.5, also have to consider the project allowance, for less than 1.3, GPS feeder requirements VSWR smaller than 2.5

return Loss =-20*log10 ((VSWR-1)/( VSWR + 1))

Summary of return loss and VSWR Loss and VSWR