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Complex Load VSWR Calculator
Calculate voltage standing wave ratio from a real reference impedance and a finite complex load impedance. Choose input units and calculate one value within the stated conditions.
Inputs
Calculations run in this browser. Scientific notation such as 1.2e-3 is supported. Do not group thousands.
Result
Voltage standing wave ratio VSWR
Enter values and select Calculate.
Γ = (Z_L−Z₀)/(Z_L+Z₀); VSWR = (1+|Γ|)/(1−|Γ|)
Assumptions
Required: a lossless line with positive real Z₀ and a passive load with Re(Z_L) ≥ 0. Positive reactance is inductive and negative reactance is capacitive. A short or purely reactive load gives complete reflection and infinite VSWR. An open circuit has the same limit, while this form accepts only finite complex impedances. Excluded: active negative resistance, complex reference impedances and position dependence on a lossy line.
Displayed values are floating-point approximations. Design safety factors and unprovided error contributions are not calculated.
Formula references and credits
NaNa Lab created the code, descriptions, icons and preview images. Text, figures and code from the linked references have not been reproduced.
Physical constants: NIST / CODATA 2022. The values of μ₀ and ε₀ are measured recommendations, not exact defining constants. Values and precision notes are in the source record.
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