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A spiral antenna is a type of radio frequency antenna shaped as a spiral, [1]: 14‑2 first described in 1956. [2] Archimedean spiral antennas are the most popular, while logarithmic spiral antennas are independent of frequency: [3] the driving point impedance, radiation pattern and polarization of such antennas remain unchanged over a large bandwidth. [4]
The antenna gain, or power gain of an antenna is defined as the ratio of the intensity (power per unit surface area) radiated by the antenna in the direction of its maximum output, at an arbitrary distance, divided by the intensity radiated at the same distance by a hypothetical isotropic antenna which radiates equal power in all directions.
Inevitably some antennas won't conveniently fit into any one basic type, so the last section on real antennas is an "everything else" category for a few peculiar antennas that don't fit cleanly into any of the categories or subcategories used in this article; for example, random wire antennas and antennas that are laid down on the ground ...
An in-building cellular enhancement system, commonly implemented in conjunction with a distributed antenna system (DAS), is a telecommunications solution which is used to extend and distribute the cellular signal of a given mobile network operator (hereafter abbreviated as an MNO) within a building.
A fractal antenna is an antenna that uses a fractal, self-similar design to maximize the effective length, or increase the perimeter (on inside sections or the outer structure), of material that can receive or transmit electromagnetic radiation within a given total surface area or volume.
The first modern horn antenna in 1938 with inventor Wilmer L. Barrow. A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz. [1]