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Yet the Yagi's higher gain compared to the LPDA makes it the best for fringe reception, and complicated Yagi designs and combination with other antenna technologies have been developed to permit its operation over the broad television bands. The Yagi–Uda antenna was named an IEEE Milestone in 1995. [10]
The output indicates that the antenna has a maximum gain of 9.75 dBi, a little over three times the gain of an isotropic antenna. However, as the signal moves even five degrees to the side, this has dropped to 9.5. When you reach 75 degrees off the front, the antenna begins to have negative gain.
An antenna array consisting of two such antennas, one above the other and driven in phase has a gain of up to 17 dBi. Being log-periodic, the antenna's main characteristics ( radiation pattern , gain, driving point impedance ) are almost constant over its entire frequency range, with the match to a 300 Ω feed line achieving a standing wave ...
The addition of parasitic elements gives a diminishing improvement in the antenna's gain. [2] Adding a reflector to a dipole, to make a 2 element Yagi, increases the gain by about 5 dB over the dipole. Adding a director to this, to give a 3 element Yagi, gives a gain of about 7 dB over a dipole.
Since it is constructed from dipoles, often its antenna gain is expressed in dB d, but listed only as dB. This ambiguity is undesirable with respect to engineering specifications. A Yagi–Uda antenna's maximum directivity is 8.77 dB d = 10.92 dB i. Its gain necessarily must be less than this by the factor η, which must be negative in units of dB.
A high-gain antenna (HGA) is a directional antenna with a focused, narrow beam width, permitting more precise targeting of the radio signals. [1] Most commonly referred to during space missions , [ 2 ] these antennas are also in use all over Earth , most successfully in flat, open areas where there are no mountains to disrupt radiowaves.
Omnidirectional radiation patterns are produced by the simplest practical antennas, monopole and dipole antennas, consisting of one or two straight rod conductors on a common axis. Antenna gain (G) is defined as antenna efficiency (e) multiplied by antenna directivity (D) which is expressed mathematically as: =.
When considering an antenna's directional pattern, gain with respect to a dipole does not imply a comparison of that antenna's gain in each direction to a dipole's gain in that direction. Rather, it is a comparison between the antenna's gain in each direction to the peak gain of the dipole (1.64). In any direction, therefore, such numbers are 2 ...