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In telecommunications, the effective height of an antenna is the height of the antenna's center of radiation above the ground. In low-frequency applications involving loaded or nonloaded vertical antennas, the effective height is the moment of the current distribution in the vertical section, divided by the input current. For an antenna with a ...
The Friis transmission formula is used in telecommunications engineering, equating the power at the terminals of a receive antenna as the product of power density of the incident wave and the effective aperture of the receiving antenna under idealized conditions given another antenna some distance away transmitting a known amount of power. [1]
An antenna designer must take into account the application for the antenna when determining the gain. High-gain antennas have the advantage of longer range and better signal quality, but must be aimed carefully in a particular direction. Low-gain antennas have shorter range, but the orientation of the antenna is inconsequential.
G: the antenna gain; is the magnetic constant; is the electric constant; For antennas which are not defined by a physical area, such as monopoles and dipoles consisting of thin rod conductors, the effective length (units: meter) is used to measure the ratio between voltage and electric field.
Height above average terrain (HAAT), or (less popularly) effective height above average terrain (EHAAT), is the vertical position of an antenna site above the surrounding landscape. HAAT is used extensively in FM radio and television , as it is more important than effective radiated power (ERP) in determining the range of broadcasts ( VHF and ...
h is the height of the antenna, λ is the wavelength, and I 0 is the RMS input current in amperes. This formula shows that the radiated power depends on the product of the base current and the effective height, and is used to determine how many metre-amps are required to achieve a given amount of radiated power.
For a given frequency, the antenna's effective area is proportional to the gain. An antenna's effective length is proportional to the square root of the antenna's gain for a particular frequency and radiation resistance. Due to reciprocity, the gain of any antenna when receiving is equal to its gain when transmitting.
It can be used for base-station antenna heights ranging from 30–1000 m. Okumura developed a set of curves giving the median attenuation relative to free space (A mu), in an urban area over a quasi-smooth terrain with a base station effective antenna height (hte) of 200 m and a mobile antenna height (hre) of 3 m. These curves were developed ...