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STEP 05 / 06 · ABOUT 5 MIN

Separate SWR from loss

A good match alone does not prove good efficiency.

Standing wave ratio describes matching at the point being considered. SWR 1:1 means no reflected wave there. It does not say what fraction of input power is radiated as the wanted radio wave. A suitable termination can also show good SWR.

Feed-line loss reduces power at the antenna and also attenuates the returning wave. A reading at the shack end of a long lossy line can therefore look better than at the feed point. Check the measurement setup, reference and line before altering the antenna.

Your turn.

Calculate SWR 2:1: reflected power is approximately 11.1%. Then open the high-SWR check path and start with the measurement setup.

Explore SWR 2:1 →Check the measurement setup systematically →
UNDERSTAND & APPLY

Check your understanding

What does SWR 1:1 alone prove?

Sources & further documentation

Your learning path— / 6
  1. Start with the purpose
  2. Turn frequency into length
  3. Divide the dipole
  4. Include the return path
  5. Separate SWR from loss
  6. Explain your design

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