Deep Dive: E3A06
The correct answer is B: Switch to a lower frequency HF band. What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness is to switch to a lower frequency HF band. Lower frequencies work better when MUF decreases. For amateur radio operators, this is important for maintaining long-distance contacts. Understanding this helps when operating HF.
Why Other Answers Are Wrong
Option A: Incorrect. Switching to higher frequency won't work - when MUF decreases, you need lower frequency. Higher frequency is wrong. Option C: Incorrect. Changing to higher takeoff angle antenna won't help - you need to switch to lower frequency. Higher takeoff angle isn't the solution. Option D: Incorrect. Changing to greater beamwidth antenna won't help - you need to switch to lower frequency. Greater beamwidth isn't the solution.
Exam Tip
MUF decreases due to darkness = switch to lower frequency HF band. Think 'M'UF 'D'ecreases = 'M'ove 'D'own in frequency. Lower frequencies work better when MUF decreases. Not higher frequency, not higher takeoff angle, not greater beamwidth - just lower frequency.
Memory Aid
MUF decreases due to darkness = switch to lower frequency HF band. Think 'M'UF 'D'ecreases = 'D'own in frequency. Lower frequencies work better when MUF decreases. Important for maintaining long-distance contacts.
Real-World Example
A long-distance contact when MUF decreases due to darkness: The Maximum Usable Frequency (MUF) drops as the ionosphere changes. To continue the contact, you should switch to a lower frequency HF band (e.g., from 20m to 40m, or 40m to 80m). Lower frequencies can still propagate when MUF decreases. This is the action - switch to lower frequency.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E3A
Reference: 2024-2028 Question Pool · E3 - Radio Wave Propagation
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E3A topic.