Question
What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?
Answer Options
- A) 112
- B) 50
- C) 19
- D) 12
Correct Answer: C
Explanation
This requires a calculation using a specialized formula for a quarter-wavelength antenna in feet: L \text{ (feet)} \approx 234 / f \text{ (MHz)}. For 146\text{ MHz}, L \text{ (feet)} \approx 234 / 146 \approx 1.6\text{ feet}.
To convert this length to inches, you multiply by 12 inches per foot: 1.6 \text{ feet} \times 12 \text{ inches/foot} \approx 19.2\text{ inches}. The closest correct answer is 19 inches. This is a common antenna size for mobile and portable operation on the 2-meter band (144-148 MHz).
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