VSWR to Reflected Power Calculator

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 VSWR

Formula

 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.

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.

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