This tool finds the percent (%) of power that’s reflected back for a specified value of Voltage Standing Wave Ratio (VSWR).
Calculator
Enter the VSWR. The % reverse power and the reflection coefficient (Γ) will be calculated.
Reflected Power to VSWRFormula
Γ = (VSWR – 1)/(VSWR + 1)
Reverse Power% = 100*|Γ|2
VSWR is a number greater than 1.
It is often expressed as a ratio. For instance a VSWR of 2 is written as 2:1.
What does a VSWR of 1.5 mean?
Using the calculator above, for a VSWR of 1.5, the reflected power is 4%. The balance of power (96%) is transmitted forward. In most applications, this is considered a good value.
It’s not unusual however, to encounter higher values of VSWR. For instance the Local Oscillator port of the ADE mixer has a VSWR as high as 4.
One technique to improving the mismatch is to add an attenuator pad (typically 3 dB) between the signal source and LO port of the mixer. Here is a more detailed post on how to improve VSWR.
As the VSWR increases, so also does the percentage of reflected power.
An ideal value of VSWR is 1 where none of the power is reflected and all of it is transmitted forward. This is the most efficient scenario.