The antennas are characterized by a number of parameters. Radiation pattern is a graphic representation of radiation characteristics of an antenna according to direction (azimuth and elevation coordinates). Most often represent the radiated power density, but also can find diagrams or phase bias (military antennas). Considering the radiative pattern, we can make a general classification of types of antenna and we can define the directivity of a receiver (isotropic antenna, directional, bi-directional, omni).
This parameter is defined as the ratio between the maximum radiated power in a geometric direction and power radiated in opposite direction. When this relationship is reflected in dB scale, the ratio F / B (Front / Back) is the difference in dB between the maximum radiation level and radiation level of 180 degrees. This parameter is especially useful when interference back is critical in choosing the antenna that we use.
Beamwidth: The angular range of directions in which the radiation of a beam takes a value 3 dB below the maximum. The direction in which the radiated power is halved. Ratio at the secondary main lobe (SLL): The ratio in dB between the maximum value of main lobe and the maximum value of secondary lobe. Front-back ratio (FBR): The ratio in dB between the value of maximum radiation and the same direction and opposite direction.
Loops are only effective at resonance, and must therefore be geared to operate, high q, very narrow bandwidth. All within about 10 wavelengths (near field) of an antenna may affect its radiation patterns. An antenna is the most "sensitive" in its main cones, there where it has "gain" in a free field radiation pattern.
If the antenna is replaced by the radiation resistance, this would do their job, ie, would produce the same amount of power that the antenna would radiate. The radiation resistance is equal to the ratio of the power radiated by the aerial divided by the square of the current in its feed point. One could obtain an mast efficiency, given that is the ratio of the radiated power and the dissipated power.
The antenna location should have unrestricted access to just above the the sky. Earth would reflect more or less of radio waves. This depends on: mast placed as high as possible so that there are no obstructions between the transmitter and receiver. Satellite or interstellar radio propagation (Earth to satellite, space shuttle) or (satellite, space shuttle to Earth). There must be no obstructions between the satellite and ground transmitters.
Every day use of aerials to transmit and receive signals (data) throughout the world by millions of people is ordinary. General: Everything is connected without cables using in some degree antennas for the exchange of information (data). An aerial is a (metal wire) device designed for the purpose of emitting or receiving electromagnetic waves into free space. A transmitter antenna transforms electrical energy into electromagnetic waves, and a receiver performs the inverse function.
The wire transmitters are analyzed from the electrical currents of the conductors. Aperture aerials are those that use surfaces or openings to direct the electromagnetic beam which concentrate their transmission and reception antenna system in one direction.
This parameter is defined as the ratio between the maximum radiated power in a geometric direction and power radiated in opposite direction. When this relationship is reflected in dB scale, the ratio F / B (Front / Back) is the difference in dB between the maximum radiation level and radiation level of 180 degrees. This parameter is especially useful when interference back is critical in choosing the antenna that we use.
Beamwidth: The angular range of directions in which the radiation of a beam takes a value 3 dB below the maximum. The direction in which the radiated power is halved. Ratio at the secondary main lobe (SLL): The ratio in dB between the maximum value of main lobe and the maximum value of secondary lobe. Front-back ratio (FBR): The ratio in dB between the value of maximum radiation and the same direction and opposite direction.
Loops are only effective at resonance, and must therefore be geared to operate, high q, very narrow bandwidth. All within about 10 wavelengths (near field) of an antenna may affect its radiation patterns. An antenna is the most "sensitive" in its main cones, there where it has "gain" in a free field radiation pattern.
If the antenna is replaced by the radiation resistance, this would do their job, ie, would produce the same amount of power that the antenna would radiate. The radiation resistance is equal to the ratio of the power radiated by the aerial divided by the square of the current in its feed point. One could obtain an mast efficiency, given that is the ratio of the radiated power and the dissipated power.
The antenna location should have unrestricted access to just above the the sky. Earth would reflect more or less of radio waves. This depends on: mast placed as high as possible so that there are no obstructions between the transmitter and receiver. Satellite or interstellar radio propagation (Earth to satellite, space shuttle) or (satellite, space shuttle to Earth). There must be no obstructions between the satellite and ground transmitters.
Every day use of aerials to transmit and receive signals (data) throughout the world by millions of people is ordinary. General: Everything is connected without cables using in some degree antennas for the exchange of information (data). An aerial is a (metal wire) device designed for the purpose of emitting or receiving electromagnetic waves into free space. A transmitter antenna transforms electrical energy into electromagnetic waves, and a receiver performs the inverse function.
The wire transmitters are analyzed from the electrical currents of the conductors. Aperture aerials are those that use surfaces or openings to direct the electromagnetic beam which concentrate their transmission and reception antenna system in one direction.
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