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The electrical length of an antenna, like a transmission line, is its length in wavelengths of the current on the antenna at the operating frequency. [ 1 ] [ 12 ] [ 13 ] [ 4 ] : p.91–104 An antenna's resonant frequency , radiation pattern , and driving point impedance depend not on its physical length but on its electrical length. [ 14 ]
Free-space path loss. In telecommunications, the free-space path loss (FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). [1]
For a typical k of about 0.95, the above formula for the corrected antenna length can be written, for a length in meters as 143 / f , or a length in feet as 468 / f where f is the frequency in megahertz. [18]
For such an antenna, the near field is the region within a radius r ≪ λ, while the far-field is the region for which r ≫ 2 λ. The transition zone is the region between r = λ and r = 2 λ . The length of the antenna, D, is not important, and the approximation is the same for all shorter antennas (sometimes idealized as so-called point ...
In electromagnetics, an antenna's gain is a key performance parameter which combines the antenna 's directivity and radiation efficiency. The term power gain has been deprecated by IEEE. [1] In a transmitting antenna, the gain describes how well the antenna converts input power into radio waves headed in a specified direction. In a receiving ...
Antennas. A ferrite loopstick antenna, a small loop used for AM reception in a portable radio, consisting of a wire wound around a ferrite core; the most common type of loop antenna today. A loop antenna is a radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor, that for transmitting is usually fed by a ...
Aperture (antenna) In electromagnetics and antenna theory, the aperture of an antenna is defined as "A surface, near or on an antenna, on which it is convenient to make assumptions regarding the field values for the purpose of computing fields at external points. The aperture is often taken as that portion of a plane surface near the antenna ...
The monopole is often used as a resonant antenna. The rod functions as an open resonator for radio waves and oscillates with standing waves of voltage and current along its length. The length of the antenna, therefore, is determined based on the wavelength of the desired radio waves. The most common form is the quarter-wave monopole, in which ...