Subelement A: RADAR Principles – 10 Key Topics – 10 Exam Questions – 8 Drawings— Topic 2: Distance and Time
Question 8-2A4
Element 8 (RADAR)If a target is 5 miles away, how long does it take for the RADAR echo to be received back at the antenna?
Explanation
A RADAR echo travels from the antenna to the target and back, meaning it covers twice the stated distance. For a target 5 miles away, the total travel distance for the pulse is 10 miles.
In amateur radio and general radar calculations, "miles" in distance problems are often interpreted as *nautical miles*. A common constant for radar range calculations states that a radio wave travels one nautical mile and returns (a round trip) in approximately 12.36 microseconds.
Therefore, for a target 5 nautical miles away, the total time for the echo to be received back at the antenna is $5 \text{ nautical miles} \times 12.36 \text{ microseconds/nautical mile (round trip)} = 61.8 \text{ microseconds}$. This value closely matches option D. Other options do not align with standard radar calculation constants.
Related Questions
8-2A2 One RADAR mile is how many microseconds?8-2A3 RADAR range is measured by the constant:8-2A5 How long would it take for a RADAR pulse to travel to a target 10 nautical miles away and return to the RADAR receiver?8-2A6 What is the distance in nautical miles to a target if it takes 308.5 microseconds for the RADAR pulse to travel from the RADAR antenna to the target and back.8-30D1 What are the usual input signals to the video amplifier?