vertical incidence

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• Near Vertical Incidence Skywave — An NVIS antenna configuration is a horizontally polarized radiating element. Near Vertical Incidence Skywave, or NVIS, is a radio wave propagation method that provides usable signals in the range between groundwave and skywave distances (usually… …   Wikipedia

• Vertical axis wind turbine — Vertical axis wind turbines (VAWT) are a type of wind turbine where the main rotor shaft runs vertically. Among the advantages of this arrangement are that generators and gearboxes can be placed close to the ground, and that VAWT do not need to… …   Wikipedia

• Incidence structure — In combinatorial mathematics, an incidence structure is a triple :C=(P,L,I)., where P is a set of points , L is a set of lines and I subseteq P imes L is the incidence relation. The elements of I are called flags. If :(p,ell) in I,we say that… …   Wikipedia

• Ionosphere — The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner …   Wikipedia

• geomagnetic field — Magnetic field associated with the Earth. It is essentially dipolar (i.e., it has two poles, the northern and southern magnetic poles) on the Earth s surface. Away from the surface, the field becomes distorted. Most geomagnetists explain the… …   Universalium

• Loop antenna — A shortwave loop antenna A loop antenna is a radio antenna consisting of a loop (or loops) of wire, tubing, or other electrical conductor with its ends connected to a balanced transmission line. Within this physical description there are two very …   Wikipedia

• Skywave — is the propagation of electromagnetic waves bent (refracted) back to the Earth s surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station… …   Wikipedia

• Jindalee Operational Radar Network — The Jindalee Operational Radar Network (JORN) is an over the horizon radar network that can monitor air and sea movements across 37,000km2. It has an official range of 3,000 km but depending upon certain atmospheric conditions has a range up to… …   Wikipedia

• NVIS — Le N.V.I.S. (Near Vertical Incidence Skywave), en Français: onde radio ionosphèrique à incidence quasi verticale, est un mode de propagation utilisé pour des radiocommunications locales et régionales dans la bande des moyennes fréquences et… …   Wikipédia en Français

• 80-meter band — The 80 meter or 3.5 MHz band is a core amateur radio frequency band, allocated frequencies from 3.5 to 4.0 MHz in IARU Region 2, and generally 3.5 to 3.8 or 3.9 MHz in Regions 1 and 3 respectively. The portion of the band used for voice… …   Wikipedia

• Critical frequency — In telecommunication, the term critical frequency has the following meanings: In radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, and above which it penetrates through, an… …   Wikipedia