Question
What is the feed point impedance of an end-fed half-wave antenna?
Answer Options
- A) Very low
- B) Approximately 50 ohms
- C) Approximately 300 ohms
- D) Very high
Correct Answer: D
Explanation
The current distribution on a half-wave antenna is minimum at the ends and maximum at the center. Feed point impedance (Z = V/I) is inversely proportional to current.
When a half-wave antenna is fed at the end (end-fed), the feed point is at a location of very low current and maximum voltage. This results in a very high feed point impedance, typically ranging from 2,500 to 5,000 \text{ ohms}. This impedance requires a specialized high-ratio matching transformer (unun) or an antenna tuner to match it to 50 \text{ ohm} coaxial cable.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!