Deep Dive: G3B11
The correct answer is A: Propagation via ordinary skywave communications is not possible over that path. What happens to HF propagation when the LUF exceeds the MUF is that propagation via ordinary skywave communications is not possible over that path. If LUF is higher than MUF, there's no usable frequency range - all frequencies are either too low (below LUF, too much absorption) or too high (above MUF, pass through). For amateur radio operators, this means the path is closed. Understanding this helps explain when paths are unusable.
Why Other Answers Are Wrong
Option B: Incorrect. HF communications aren't enhanced when LUF exceeds MUF - the path is closed, not enhanced. No frequencies work. Option C: Incorrect. Double-hop propagation isn't more common - the path is closed, so no propagation occurs. Multiple hops don't help if LUF > MUF. Option D: Incorrect. Propagation on all HF frequencies isn't enhanced - the path is closed. No frequencies work when LUF exceeds MUF.
Exam Tip
LUF exceeds MUF = propagation not possible. Think 'L'UF > 'M'UF = 'L'owest > 'M'aximum = 'N'o usable frequency. If LUF exceeds MUF, there's no frequency range that works - path is closed. Not enhanced, not double-hop, not all frequencies - just no propagation possible.
Memory Aid
LUF exceeds MUF = propagation not possible. Think 'L'UF > 'M'UF = 'N'o usable frequency. If LUF exceeds MUF, there's no frequency range that works - path is closed. Propagation via ordinary skywave is not possible.
Real-World Example
LUF for a path is 15 MHz, and MUF is 12 MHz. Since LUF (15 MHz) exceeds MUF (12 MHz), there's no usable frequency - frequencies below 15 MHz are too low (below LUF, too much absorption), and frequencies above 12 MHz are too high (above MUF, pass through). The path is closed - no skywave propagation is possible.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G3B
Reference: 2023-2027 Question Pool · G3 - Radio Wave Propagation
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G3B topic.