page_title: Microwave transmission
section_title: Uses
hierarchical_section_title: Microwave transmission / Uses
caption_attribution_description: Deutsch: Die größte Erdfunkstelle der Welt bei Raisting (in der Nähe des Ammersees) ist eine Bodenstation für die Kommunikation mit Nachrichtensatelliten und ist mit ihren großen Parabolantennen weithin sichtbar. English: A parabolic satellite communication antenna at the biggest facility for satellite communication in Raisting, Bavaria, Germany. This type of parabolic antenna is called a Cassegrain antenna. The radio waves emerge from the hole in the center of the dish and are focussed on a convex subreflector suspended on the supports in front of the dish. The waves are reflected back toward the main dish, which reflects them forward to form the outgoing beam aimed at the satellite. Français&#160;: Le plus gros centre de communication satellitaire à Raisting, en Bavière (Allemagne).
context_page_description: Microwave transmission is the transmission of information by microwave radio waves. Although an experimental 40-mile microwave telecommunication link across the English Channel was demonstrated in 1931, the development of radar in World War II provided the technology for practical exploitation of microwave communication. In the 1950s, large transcontinental microwave relay networks, consisting of chains of repeater stations linked by line-of-sight beams of microwaves were built in Europe and America to relay long distance telephone traffic and television programs between cities. Communication satellites which transferred data between ground stations by microwaves took over much long distance traffic in the 1960s. In recent years, there has been an explosive increase in use of the microwave spectrum by new telecommunication technologies such as wireless networks, and direct-broadcast satellites which broadcast television and radio directly into consumers' homes.
context_section_description: Microwaves are widely used for point-to-point communications because their small wavelength allows conveniently-sized antennas to direct them in narrow beams, which can be pointed directly at the receiving antenna. This allows nearby microwave equipment to use the same frequencies without interfering with each other, as lower frequency radio waves do. Another advantage is that the high frequency of microwaves gives the microwave band a very large information-carrying capacity; the microwave band has a bandwidth 30 times that of all the rest of the radio spectrum below it.  A disadvantage is that microwaves are limited to line of sight propagation; they cannot pass around hills or mountains as lower frequency radio waves can.
  Microwave radio transmission is commonly used in point-to-point communication systems on the surface of the Earth, in satellite communications, and in deep space radio communications. Other parts of the microwave radio band are used for radars, radio navigation systems, sensor systems, and radio astronomy.
  The next higher part of the radio electromagnetic spectrum, where the frequencies are above 30 GHz and below 100 GHz, are called "millimeter waves" because their wavelengths are conveniently measured in millimeters, and their wavelengths range from 10 mm down to 3.0 mm (Higher frequency waves are smaller in wavelength). Radio waves in this band are usually strongly attenuated by the Earthly atmosphere and particles contained in it, especially during wet weather. Also, in a wide band of frequencies around 60 GHz, the radio waves are strongly attenuated by molecular oxygen in the atmosphere. The electronic technologies needed in the millimeter wave band are also much more difficult to utilize than those of the microwave band.
  Wireless transmission of information
  One-way (e.g. television broadcasting) and two-way telecommunication using communications satellite
  Terrestrial microwave relay links in telecommunications networks including backbone or backhaul carriers in cellular networks
  Wireless transmission of power
  Proposed systems e.g. for connecting solar power collecting satellites to terrestrial power grids
caption: A parabolic satellite antenna for Erdfunkstelle Raisting, based in Raisting, Bavaria, Germany
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