Extra exam question E9F09
Subelement E9, ANTENNAS AND TRANSMISSION LINES· Group E9F
What impedance does a 1/4-wavelength transmission line present to an RF generator when the line is shorted at the far end?
- A.Very high impedance (correct answer)
- B.Very low impedance
- C.The same as the characteristic impedance of the transmission line
- D.The same as the generator output impedance
WhyA 1/4-wavelength transmission line shorted at the far end presents a very high impedance to an RF generator. A quarter-wavelength line inverts whatever impedance is at its far end, so a line shorted at the far end (very low impedance) presents very high impedance back at the generator, the opposite of what a half-wave line does, answer A. It doesn't present very low impedance, doesn't present the line's own characteristic impedance regardless of termination, and doesn't simply mirror the generator's output impedance.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
Related questions
- E9F01What is the velocity factor of a transmission line?
- E9F02Which of the following has the biggest effect on the velocity factor of a transmission line?
- E9F03Why is the electrical length of a coaxial cable longer than its physical length?
- E9F04What impedance does a 1/2-wavelength transmission line present to an RF generator when the line is shorted at the far end?
- E9F05What is microstrip?