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.
Comparing an antenna yagi with a satellite, the antenna yagi have a F / B ratio of about 15 dB (depending on model and manufacturer) while for the parabolic relationship F / B is> 35dB (depending on model and manufacturer) . This is observed as "good" antenna on rejection of signals by the rear. The higher the paramentro in parabolic antennas will be better. The 15 dB of antenna yagui it can also be interpreted as the attenuation that would have on the system, if for example a bounced capture of a building, by the rear of the wave. Radiation resistance - when power is supplied to an aerial, radiating part of it and part is converted into heat dissipating. When talking about radiation resistance, it is made taking into account that cannot be measured directly.
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.
There are three basic types of transmitters: wire, aperture and planar antennas. Also, clusters of these aerials (arrays) are usually considered in the literature as another basic type of antenna. Wire transmitters are variants whose radiating elements are wire conductors having a negligible section relative to wavelength employment.
The polarization can be linear, circular and elliptical. Linear polarization can take different orientations (horizontal, vertical, +45, -45). The circular or elliptical polarizations can be right or left (right-handed or left-handed), according to the direction of rotation of the field (observed away from the antenna). Transmitters within decoupling coefficient defined polarization. This measures the amount of power that is capable of receiving a polarized antenna of a form having an effective.
If, in each of these ports, a diplexer, which separates the frequency bands of emission and reception, it will be a feeder four ports with a single antenna will be able to send and receive both polarizations simultaneously placed. At other times, these antennas have only two ports, one for emitting a polarization and the other to receive the opposite polarization.
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.
Comparing an antenna yagi with a satellite, the antenna yagi have a F / B ratio of about 15 dB (depending on model and manufacturer) while for the parabolic relationship F / B is> 35dB (depending on model and manufacturer) . This is observed as "good" antenna on rejection of signals by the rear. The higher the paramentro in parabolic antennas will be better. The 15 dB of antenna yagui it can also be interpreted as the attenuation that would have on the system, if for example a bounced capture of a building, by the rear of the wave. Radiation resistance - when power is supplied to an aerial, radiating part of it and part is converted into heat dissipating. When talking about radiation resistance, it is made taking into account that cannot be measured directly.
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.
There are three basic types of transmitters: wire, aperture and planar antennas. Also, clusters of these aerials (arrays) are usually considered in the literature as another basic type of antenna. Wire transmitters are variants whose radiating elements are wire conductors having a negligible section relative to wavelength employment.
The polarization can be linear, circular and elliptical. Linear polarization can take different orientations (horizontal, vertical, +45, -45). The circular or elliptical polarizations can be right or left (right-handed or left-handed), according to the direction of rotation of the field (observed away from the antenna). Transmitters within decoupling coefficient defined polarization. This measures the amount of power that is capable of receiving a polarized antenna of a form having an effective.
If, in each of these ports, a diplexer, which separates the frequency bands of emission and reception, it will be a feeder four ports with a single antenna will be able to send and receive both polarizations simultaneously placed. At other times, these antennas have only two ports, one for emitting a polarization and the other to receive the opposite polarization.
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