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One technique to reduce the reflected signal from the input or output of any device is to place an attenuator before or after the device. The attenuator reduces the reflected signal two times the value of the attenuation, while the transmitted signal receives the nominal attenuation value.

To use this calculator to determine the effective VSWR/Return Loss of an attenuator/device combination, enter the attenuation, VSWR or Return Loss, and Gain of the device, then press the ‘Calculate button’. Pressing the ‘Calculate’ button with no inputs will load the example below.

vswr reduction calculator
Attenuation dB Gain dB
  Reflected Signal VSWR
Return Loss (dB)
Effective VSWR Effective Return Loss dB Effective Gain dB

An amplifier with a 2:1 Input VSWR and 16 dB gain must be reduced to below 1.5:1. A 3 dB Attenuator can be placed before the amplifier to yield an effective VSWR of 1.401 with a gain reduction to 13 dB.