General exam question G4E05
Subelement G4, AMATEUR RADIO PRACTICES· Group G4E
Which of the following most limits an HF mobile installation?
- A.“Picket fencing”
- B.The wire gauge of the DC power line to the transceiver
- C.Efficiency of the electrically short antenna (correct answer)
- D.FCC rules limiting mobile output power on the 75-meter band
WhyThe efficiency of the electrically short antenna most limits an HF mobile installation. A mobile HF antenna is necessarily physically short compared to a wavelength, and that shortness drives down its radiation efficiency, which is the dominant factor limiting how well an HF mobile installation actually performs, answer C. Picket fencing (multipath flutter on FM/mobile VHF) and DC wiring gauge are real but secondary concerns, and there's no FCC power-limit rule specific to mobile 75-meter operation, so A, B, and D don't identify the primary limitation.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.
Related questions
- G4E01What is the purpose of a capacitance hat on a mobile antenna?
- G4E02What is the purpose of a corona ball on an HF mobile antenna?
- G4E03Which of the following direct, fused power connections would be the best for a 100-watt HF mobile installation?
- G4E04Why should DC power for a 100-watt HF transceiver not be supplied by a vehicle’s auxiliary power socket?
- G4E06What is one disadvantage of using a shortened mobile antenna as opposed to a full-size antenna?