Transmission Line Impedance
Line & load
Enter characteristic (Z₀) and load impedance; reflection, VSWR and return loss appear live.
Match quality
How to use this calculator
A transmission line has a characteristic impedance Z₀ (e.g. 50 Ω for RF, 75 Ω for video). When the load ZL equals Z₀ the line is matched and nothing is reflected. This tool computes the reflection coefficient Γ = (ZL − Z₀)/(ZL + Z₀), the voltage standing-wave ratio VSWR = (1+|Γ|)/(1−|Γ|), and return loss in dB. Enter Z₀ and ZL and the match quality appears live.
What it means in a real circuit
A mismatch creates standing waves that reduce delivered power, distort pulses, and can overdrive a transmitter's output stage. RF engineers target VSWR < 1.5:1 (return loss > 14 dB) for healthy performance. This is the same math behind cable testing and antenna tuning — use it to sanity-check that your cable and load are compatible before trusting a measurement.