What VSWR is acceptable for most applications?

Below 2:1 is acceptable for most systems. Below 1.5:1 is good. Antenna systems often specify 1.3:1 or better.

Can VSWR damage equipment?

High VSWR reflects power back to the transmitter, causing heating. Most transmitters reduce power automatically above VSWR 3:1.

What is the relationship between VSWR and return loss?

They are different ways to express the same mismatch. Return loss = 20 x log10((VSWR+1)/(VSWR-1)) dB.

VSWR Calculator

Calculate the Voltage Standing Wave Ratio from load and characteristic impedance, or from reflection coefficient.

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Load Impedance

Characteristic Impedance

VSWR

1.50

Reflection Coefficient0.2000

Return Loss14.0 dB

Mismatch Loss0.18 dB

Power Reflected4.0 %

VSWR vs Load Impedance

View formula & how it works →

What is VSWR?

VSWR (Voltage Standing Wave Ratio) measures impedance mismatch between a transmission line and its load. A perfect match is 1:1.

Formulas

Gamma = Z_load - Z_0/Z_load + Z_0

VSWR = (1 + Gamma) / (1 - Gamma)

Return Loss = -20 x log10(Gamma) dB

Interpretation

VSWR 1.0: Perfect match (0% reflected)

VSWR 1.5: Good match (4% reflected)

VSWR 2.0: Acceptable (11% reflected)

VSWR 3.0+: Poor match (25%+ reflected)

Example Calculation

75 ohm load on a 50 ohm transmission line.

01Gamma = |75 - 50| / |75 + 50| = 25 / 125 = 0.2000
02VSWR = (1 + 0.2) / (1 - 0.2) = 1.2 / 0.8 = 1.50
03Return loss: -20 x log10(0.2) = 13.98 dB
04Power reflected: 0.04 = 4.0%

Frequently Asked Questions

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Ohm's Law Guide

A complete guide to Ohm's Law. Learn the relationship between voltage, current, and resistance, with practical examples, the power triangle, and circuit analysis tips.

VSWR Calculator

What is VSWR?

Formulas

Interpretation

Example Calculation

Frequently Asked Questions

Ohm's Law Guide

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Return Loss Calculator

Impedance Matching Calculator

Transmission Line Impedance Calculator