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).
Within the transmission we can define co-polar diagram that represents the communication from to a desired polarity and polarized radiation pattern with the opposite polarity to that you already have. The most important parameters of the radiation pattern are: pointing direction: The maximum radiation. Directivity and Gain. Main lobe constitutes angular range around the direction of maximum radiation. Side lobes are other relative maxima, lower the principal value.
This relationship also can be seen from another point of view, indicating how good the antenna in the rejection of signals from the rear. Rarely is really important, because the interference from the rear do not usually happen, but it can happen. The F / B ratio is not a very useful number because often varies greatly from one channel to another. Of course, if it is the radiation pattern, then the F / B is not needed.
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.
Within the transmission we can define co-polar diagram that represents the communication from to a desired polarity and polarized radiation pattern with the opposite polarity to that you already have. The most important parameters of the radiation pattern are: pointing direction: The maximum radiation. Directivity and Gain. Main lobe constitutes angular range around the direction of maximum radiation. Side lobes are other relative maxima, lower the principal value.
This relationship also can be seen from another point of view, indicating how good the antenna in the rejection of signals from the rear. Rarely is really important, because the interference from the rear do not usually happen, but it can happen. The F / B ratio is not a very useful number because often varies greatly from one channel to another. Of course, if it is the radiation pattern, then the F / B is not needed.
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.
About the Author:
You can visit www.hascall-denke.com for more helpful information about Form Of And Function Of Military Antennas.
Aucun commentaire:
Enregistrer un commentaire