Return loss is a measure the the power level obtained from an rf bridge network when compared to the output of the same bridge terminated in a short circuit or an open circuit. Simply put, the bridge is balanced and has no output when terminated in a 50 ohm load (1:1 VSWR) and has maximum output (infinite VSWR) when the bridge is terminated with a short or open circuit. The return loss value is the value of attenuation of the reflection signal.. For example, a 1.5:1 VSWR is the equivalent of a 14 dB return loss value. In this case the rf bridge output is 14 dB less power than if it were directly shorted or open at the "test" port.