As wireless systems expand from sub-6 GHz to millimeter-wave and sub-THz bands, the propagation channel exhibits distinct frequency-dependent behaviors driven by wave-material interactions. While distance-dependent path loss remains constant, Friis transmission formula indicates that overall path loss increases with the square of the frequency due to antenna effects. Higher frequencies experience significantly greater attenuation from diffraction and penetration through obstacles like walls and foliage, while atmospheric absorption creates sharp loss peaks around 60 GHz and 300 GHz due to oxygen and water vapor resonance. Conversely, reflection from smooth surfaces remains largely frequency-independent, though scattering behavior becomes complex as obstacle sizes relative to wavelength change. Ultimately, while dominant multipath routes often persist across bands, the signal strength and reliability degrade at higher frequencies due to these cumulative loss mechanisms.
Source: https://www.6gflagship.com/news/how-does-a-radio-channel-change-with-frequency/
Keywords: millimeter-wave, sub-THz, atmospheric absorption, path loss, wave-material interactions