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- Reflective_array_antenna abstract "In telecommunication and radar, a reflective array antenna is a class of directive antennas in which multiple driven elements are mounted in front of a flat surface designed to reflect the radio waves in a desired direction. They are often used in the VHF frequency band, and these versions often resemble a highway billboard, so they are sometimes called "billboard antennas". The curtain array is a larger version used by shortwave radio stations.Reflective array antennas usually have a number of identical driven elements, fed in phase, in front of a flat, electrically large reflecting surface to produce a unidirectional beam, increasing antenna gain and reducing radiation in unwanted directions. The individual elements are most commonly half wave dipoles, although they sometimes contain parasitic elements as well as driven elements. The reflector may be a metal sheet or more commonly a wire screen. A metal screen reflects radio waves as well as a solid metal sheet as long as the holes in the screen are smaller than about one-tenth of a wavelength, so screens are often used to reduce weight and wind loads on the antenna. They usually consist of a grill of parallel wires or rods, oriented parallel to the axis of the dipole elements. The driven elements are fed by a network of transmission lines, which divide the power from the RF source equally between the elements. This often has the circuit geometry of a tree structure.".
- Reflective_array_antenna thumbnail SCR-270-set-up.jpg?width=300.
- Reflective_array_antenna wikiPageID "41643".
- Reflective_array_antenna wikiPageRevisionID "587755874".
- Reflective_array_antenna align "left".
- Reflective_array_antenna caption "A modern form of reflective array is the "bow tie" UHF television antenna. This example has two dipole driven elements in front of a grill reflector. The "bow-tie" dipoles, consisting of two V-shaped elements, have a larger bandwidth than ordinary dipoles, allowing the antenna to cover the wide UHF television band.".
- Reflective_array_antenna caption "An ALLISS antenna, a modular type of curtain array used by international shortwave stations for broadcasting to distant areas by skywave.".
- Reflective_array_antenna caption "Enormous reflective array antenna of the Duga-3 or "Steel Yard" over-the-horizon radar system, Chernobyl, Ukraine, part of the Soviet early-warning network. It transmits at frequencies between 7 and 19 MHz. The pairs of cylindrical cages at right are the half wave dipole driven elements, fed at their center by vertical feed lines. Behind them is a reflector screen of horizontal wires, just visible in center.".
- Reflective_array_antenna direction "horizontal".
- Reflective_array_antenna hasPhotoCollection Reflective_array_antenna.
- Reflective_array_antenna image "2007.11".
- Reflective_array_antenna image "6".
- Reflective_array_antenna image "Woodpecker array.jpg".
- Reflective_array_antenna width "230".
- Reflective_array_antenna width "245".
- Reflective_array_antenna width "279".
- Reflective_array_antenna subject Category:Radio_frequency_antenna_types.
- Reflective_array_antenna comment "In telecommunication and radar, a reflective array antenna is a class of directive antennas in which multiple driven elements are mounted in front of a flat surface designed to reflect the radio waves in a desired direction. They are often used in the VHF frequency band, and these versions often resemble a highway billboard, so they are sometimes called "billboard antennas".".
- Reflective_array_antenna label "Reflective array antenna".
- Reflective_array_antenna sameAs m.0bfnl.
- Reflective_array_antenna sameAs Q7307317.
- Reflective_array_antenna sameAs Q7307317.
- Reflective_array_antenna wasDerivedFrom Reflective_array_antenna?oldid=587755874.
- Reflective_array_antenna depiction SCR-270-set-up.jpg.
- Reflective_array_antenna isPrimaryTopicOf Reflective_array_antenna.