Why is a 19-inch-long vertical antenna often used on 2 meters?
It has high gain
It is a resonant half-wave
It is a resonant quarter-wave✓Correct answer
It has low RF radiation exposure
Explanation
At 146 MHz the wavelength is about 2.05 metres, so a quarter wavelength is roughly 0.51 metres, which is close to 19 or 20 inches once normal end effects are allowed for. A half wave on 2 metres would be about twice that length.