Home » Propagation » 27 VHF and UHF bands are frequently used for satellite communication because:   a.   waves at these frequencies travel to and from the satellite relatively unaffected by the ionosphere   b.   the Doppler frequency change caused by satellite motion is much less than at HF   c.   satellites move too fast for HF waves to follow   d.   the Doppler effect would cause HF waves to be shifted into the VHF and UHF bands.