Deep Dive: E3A01
The correct answer is D: 12,000 miles, if the moon is 'visible' by both stations. What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME is 12,000 miles, if the moon is 'visible' by both stations. EME can cover up to about 12,000 miles when both stations can see the moon. For amateur radio operators, this is important for EME operation. Understanding this helps when planning EME contacts.
Why Other Answers Are Wrong
Option A: Incorrect. 2,000 miles at perigee is too short - EME can cover up to about 12,000 miles. 2,000 miles is too short. Option B: Incorrect. 2,000 miles at apogee is too short - EME can cover up to about 12,000 miles. 2,000 miles is too short. Option C: Incorrect. 5,000 miles at perigee is too short - EME can cover up to about 12,000 miles. 5,000 miles is too short.
Exam Tip
EME maximum separation = 12,000 miles if moon visible by both stations. Think 'E'ME 'M'aximum = '1'2,000 miles. EME can cover up to about 12,000 miles when both stations can see the moon. Not 2,000 miles, not 5,000 miles - just 12,000 miles.
Memory Aid
EME maximum separation = 12,000 miles if moon visible by both stations. Think 'E'ME 'M'aximum = '1'2,000 miles. EME can cover up to about 12,000 miles when both stations can see the moon. Important for EME operation.
Real-World Example
EME (Earth-Moon-Earth) communication: The approximate maximum separation between two stations is 12,000 miles, if the moon is 'visible' by both stations. This is roughly half the Earth's circumference. When both stations can see the moon, they can communicate via EME. This is the maximum separation - 12,000 miles.
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.