T3A01

Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet?

1. AThe signal path encounters different concentrations of water vapor
2. BVHF ionospheric propagation is very sensitive to path length
3. CMultipath propagation cancels or reinforces signals
4. DThe Doppler effect causes slight frequency shifts which result in changes in signal strength

Pick an answer to check it.