OneSDR contains affiliate links and is a member of the Amazon Services LLC Associates Program, eBay affiliate program, Etsy Affiliate Program. If you make a purchase using one of these links, we may receive compensation at no extra cost to you. This helps support our research, testing and writing.

VSWR to dB Return Loss Calculator

This tool computes the Return loss (in dB) from Voltage Standing Wave Ratio (VSWR).

arrow dB to VSWR

Formula

Γ = (VSWR – 1)/(VSWR + 1)

Return Loss (dB) = -20*Log10(|Γ|)

Example Calculation

A good value of VSWR is 1.5, where 96% of the power is transmitted forward and only 4% is reflected back (mismatch loss calculator) In this case, the return loss is calculated to be 14 dB.

A higher numerical value of VSWR represents a poor match. Conversely a lower VSWR value represents a good match.

As well, a higher value of VSWR converts to a lower dB value of return loss. For instance a VSWR of 2.5 translates to a return loss of 7.4 dB.

The ideal value of VSWR is 1 where none of the power is reflected back. It represents an excellent match. Note that the minimum value of VSWR is 1 – i.e. VSWR cannot be less than 1. There is no maximum value of VSWR and so it is designated as infinity  .

Mcbazel Surecom SW-102 Digital VHF/UHF 125-525Mhz Antenna Power & SWR Meter