Technician exam question T3C05
Subelement T3, RADIO WAVE PROPAGATION· Group T3C
Which of the following effects may allow radio signals to travel beyond obstructions between the transmitting and receiving stations?
- A.Knife-edge diffraction (correct answer)
- B.Faraday rotation
- C.Quantum tunneling
- D.Doppler shift
WhyKnife-edge diffraction may allow radio signals to travel beyond obstructions between the transmitting and receiving stations. Knife-edge diffraction lets a radio wave bend around the sharp edge of an obstruction, a ridgeline or a building edge, letting some signal reach a receiver that has no direct line of sight to the transmitter, answer A. Faraday rotation (B) affects polarization, not obstruction bypass, quantum tunneling (C) is a subatomic-scale phenomenon irrelevant to macroscopic radio propagation, and Doppler shift (D) affects frequency due to relative motion, not the ability to get around an obstacle.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2026-2030 NCVEC Element 2 pool (public domain); the explanation above is original writing, see our methodology.
Related questions
- T3C01Why are simplex UHF signals rarely heard beyond their radio horizon?
- T3C02What is a characteristic of HF communication compared with communications on VHF and higher frequencies?
- T3C03What is one characteristic of VHF signals received via auroral backscatter?
- T3C04Which of the following types of propagation is most commonly associated with occasional strong signals on the 10-, 6-, and 2-meter bands from beyond the radio horizon?
- T3C06What type of propagation is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?