Advanced Qualification · A-007 Feedlines and matching · A-007-002-003
What kind of impedance does a half wavelength transmission line present to the source when the line is open at the far end?
- A A very high impedance
- B The same as the characteristic impedance of the transmission line
- C The same as the output impedance of the source
- D A very low impedance
Correct answer: A — A very high impedance. From the official ISED question bank, verified word for word.
Why
A half wavelength transmission line acts like a mirror for electrical signals, meaning whatever happens at the far end appears exactly the same at the source. The full explanation — and one for every question — is in Pro.
Practise this section
Feedlines and matching at the advanced level: transmission line theory, impedance transformation, stubs and matching networks.