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Wireless & Mobility · Advanced

Voltage Standing Wave Ratio (VSWR)

The ratio describing impedance mismatch between transmitter, cable, and antenna; 1:1 is perfect.

Definition

VSWR occurs when impedance mismatches cause some RF energy to reflect back toward the transmitter. The reflected energy reduces radiated power and can damage the transmitter. Wi-Fi systems use 50-ohm components, and a VSWR of 1.5:1 or lower is generally acceptable.

Example

Using a 75-ohm cable with a 50-ohm radio raises VSWR.

Exam tip

VSWR is caused by impedance mismatch; fix it by matching component impedance.

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