The mode of propagation used for the Ultra High Frequency (UHF) range is primarily "Space waves." Space waves are electromagnetic waves that propagate through line-of-sight paths in the Earth's atmosphere. This mode of propagation is suitable for UHF signals, which typically fall in the frequency range of 300 MHz to 3 GHz. Ground waves and surface waves are more commonly associated with lower frequency bands, and sky waves are typically used for much higher frequencies (such as in the High-Frequency (HF) range).