Why is the height a vhf radio antenna important?
VHF signals are essentially Line of sight transmissions (LOS).
Like all radio waves they are attenuated by objects in their path.
Raising the aerial above the level of the interferring objects
while still maintaining an integral waveform (Usually using an
artificial ground plane or aerials less than 1/2 lambna), reduces
the attenuation and prevents distortion of the polarization pattern
thus leading to an efficient transmission path.