A radio antenna (or just aerial) is a transducer that can send and receive radio waves (electromagnetic waves) designed for radio, TV, cell phones, radar or satellite. A radio antenna is a transducer with a usable efficiency can perform one or both of these energy conversions: marketable alternating electrical energy for transmission of radio wave energy. Marketable radio wave energy to alternating electrical energy (military antennas).
Most radio aerials today is primarily designed to be able to send or receive radio waves in a narrow frequency band, for example. FM via VHF band II (87.5-108 MHz). Masts propagate / receives radio waves through coupling with the alternating magnetic field. These types of antenna are used for long-wave, medium-wave and short-wave up to about 6MHz. It is possible to realize antennas that operate according to this principle, up to 60 MHz.
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.
Bandwidth is a frequency range in which the antenna parameters meet certain characteristics. Can define impedance bandwidth, polarization, gain or other parameters. Directivity is the impedance of masts at its terminals. It is the relationship between the voltage and the input current. Z = frac V I. The impedance is a complex number. The real part of an impedance is called mast resistance and the imaginary part is reactance.
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 dimensions are generally a maximum wavelength. It is widely used in the bands of MF, HF, VHF and UHF. You can find wire antenna arrays. Examples of wire antennas are: the vertical monopole, the dipole and its evolution, the Yagi, loop antenna and the helical antenna is a special type of antenna that is used primarily on VHF and UHF. It describes a helix conductor, thereby producing a circular polarization.
The characteristics of an antenna depends on the relationship between the dimensions and the wavelength of a signal transmitted or received radio frequency. If the masts dimensions are much smaller than the wavelength are called elementary antennas, whether they have dimensions of order of a half wavelength resonating and if its size is much larger than the wavelength are directives.
Most radio aerials today is primarily designed to be able to send or receive radio waves in a narrow frequency band, for example. FM via VHF band II (87.5-108 MHz). Masts propagate / receives radio waves through coupling with the alternating magnetic field. These types of antenna are used for long-wave, medium-wave and short-wave up to about 6MHz. It is possible to realize antennas that operate according to this principle, up to 60 MHz.
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.
Bandwidth is a frequency range in which the antenna parameters meet certain characteristics. Can define impedance bandwidth, polarization, gain or other parameters. Directivity is the impedance of masts at its terminals. It is the relationship between the voltage and the input current. Z = frac V I. The impedance is a complex number. The real part of an impedance is called mast resistance and the imaginary part is reactance.
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 dimensions are generally a maximum wavelength. It is widely used in the bands of MF, HF, VHF and UHF. You can find wire antenna arrays. Examples of wire antennas are: the vertical monopole, the dipole and its evolution, the Yagi, loop antenna and the helical antenna is a special type of antenna that is used primarily on VHF and UHF. It describes a helix conductor, thereby producing a circular polarization.
The characteristics of an antenna depends on the relationship between the dimensions and the wavelength of a signal transmitted or received radio frequency. If the masts dimensions are much smaller than the wavelength are called elementary antennas, whether they have dimensions of order of a half wavelength resonating and if its size is much larger than the wavelength are directives.
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