VSWR Calculations
VSWR (Voltage Standing Wave Ratio) is the measure of how efficiently RF power is transmitted and is expressed as a ratio of the maximum to minimum amplitude (or the voltage or current) of the corresponding field components appearing on a line that feeds an antenna. To improve VSWR, this calculator also includes an extra input for adding an attenuator to increase or decrease the system VSWR.
Enter one parameter and press Calculate. You can also edit a result directly and press Calculate again.
Tip: You may also edit any result field below and then press Calculate.
Example: 6 for “6:1”
Reset clears values and restores placeholders.
| VSWR | : 1 | |
|---|---|---|
| Return Loss (dB) | dB | |
| Mismatch Loss (dB) | dB | |
| Loss in % | % | |
| Reflection Coefficient | (0..1) |
Notes: Reflection coefficient is the magnitude \( |\Gamma| \). Typical range: 0 to 1 (exclusive).
VSWR Reduction using a matched attenuator
Assuming a perfect 1:1 attenuator
Uses \( |\Gamma_{in}| = |\Gamma|/10^{A/10} \) (round-trip attenuation).
Computed from current reflection coefficient + attenuator.
Formulas
Core relationshipsVSWR / Return Loss / Mismatch Loss
\[
|\Gamma| = \frac{\mathrm{VSWR}-1}{\mathrm{VSWR}+1}
\]
\[
\mathrm{RL} = -20\log_{10}(|\Gamma|)
\]
\[
\mathrm{VSWR} = \frac{1+|\Gamma|}{1-|\Gamma|}
\]
\[
\mathrm{ML} = -10\log_{10}\!\left(1-|\Gamma|^2\right)
\]
\[
\mathrm{Loss}\% = 100\,|\Gamma|^2
\]
Definitions: VSWR is the ratio of maximum to minimum standing wave amplitude. Return loss is reflected power
expressed in dB. Mismatch loss is the reduction in power delivered to the load due to reflection.