This tool uses the forward and reverse power to calculate the VSWR (Voltage Standing Wave Ratio) and reflection coefficient (Γ). Both forward and reflected power are expressed in Watt.
Formula
Reverse Power% = 100*(Reverse Power/(Reverse Power + Forward Power))
Γ = √(Reverse Power%/100)
VSWR = (1+|Γ|)/(1-|Γ|)
Example Calculations
If the forward power is 10 Watt, and reverse power is 1 Watt, this means that 10% of the power is reflected back to the source. In this case the VSWR is 1.92 and the reflection coefficient Γ is 0.32.
If the transmit power is 25 Watt and 1 Watt is reflected back – this gives a VSWR = 1.5. Any value between 1.5 and 1 is a good value.
VSWR varies between 1 and ∞.
VSWR = 1 is ideal. In this scenario none of the input power is reflected back. Reverse power = 0 and Γ = 0
VSWR = ∞ is the worst condition. All of the power is reflected back. In this situation (refer to the equations above), Γ = 1 and VSWR = 2/0 = ∞.
Related Blog Posts and Calculators
- How to improve VSWR – a simple technique to reduce mismatch
- VSWR to Reflected Power
- Impedance Mismatch Calculator
- VSWR from Forward and Reflected Power
- Return Loss to VSWR