Extremely high frequency paths. They are not reflected by the ionosphere nor do they travel along the Earth as ground waves as lower frequency radio waves do. At typical power densities they are blocked by building walls and suffer significant attenuation passing through foliage. Absorption by atmospheric gases is a significant factor throughout the band and increases with frequency. However, it is maximum at a few specific absorption lines, mainly those of oxygen at 60 GHz and water vapor at 24 GHz and 184 GHz. At frequencies in the "windows" between these absorption peaks, millimeter waves have much less atmospheric attenuation and greater
Earth–Moon–Earth communication facility to rotate antennas to adjust polarization. Another component is Faraday rotation on the Earth-Moon-Earth path; the plane of polarization of radio waves rotates as they pass through ionized layers of the Earth's atmosphere. This effect is more pronounced at lower VHF frequencies and becomes less significant at 1296 MHZ and above. Some of the polarization mismatch loss can be alleviated by using a larger antenna array (more Yagi elements or a larger dish). Earth–Moon–Earth communication Earth–Moon–Earth communication (EME), also known as moon bounce, is a radio communications technique that relies on the propagation of radio waves from an Earth-based