VSWR

What is this formula?

VSWR calculates the voltage standing wave ratio on a transmission line from the magnitude of the reflection coefficient.

When to use it

Use this formula when evaluating impedance matching, antenna systems, RF transmission lines, microwave circuits, and signal reflection problems.

Example

A transmission line has:

Reflection coefficient magnitude = 0.20

Formula:

VSWR = (1 + |Γ|) / (1 − |Γ|)

Substitution:

VSWR = (1 + 0.20) / (1 − 0.20)

Result:

VSWR = 1.5

Applications

Antenna matching

RF transmission lines

Microwave engineering

Cable testing

Signal integrity analysis

Note

VSWR is valid for sinusoidal steady-state transmission line analysis. A value of 1 indicates perfect matching, while higher values indicate stronger reflections. In practice, VSWR is often measured with RF instruments and depends on frequency, cable losses, connectors, and load impedance.