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helical antenna การใช้

ประโยคมือถือ
  • In most cases, helical antennas are mounted over a ground plane.
  • The prominent helical antenna received telecommands from a ground station.
  • Helical antennas can operate in one of two principal modes  normal mode or axial mode.
  • A common form of normal-mode helical antenna is the " rubber ducky antenna " used in portable radios.
  • A "'helical antenna "'is an antenna consisting of a conducting wire wound in the form of a helix.
  • One application that has used heatshrink in large quantities since the early 1970s is the covering of fibreglass helical antennas, used extensively for 27 MHz CB Radio.
  • In the " axial mode " or " end-fire " helical antenna, the dimensions of the helix are comparable to a wavelength.
  • In radio transmission, circular spacecraft communications, or where the polarisation of the signal may change, so end-fire helical antennas are frequently used for these applications.
  • For television broadcasting specialized vertical radiators that are mostly modifications of the slot antenna or helical antenna are used : the slotted cylinder, zig-zag, and panel antennas.
  • There are many ways to make a high-gain antenna-the most common are parabolic antennas, helical antennas, yagi antennas, and phased arrays of smaller antennas of any kind.
  • In the " normal mode " or " broadside " helical antenna, the dimensions of the helix ( the diameter and the linearly polarised parallel to the helix axis.
  • Lunokhod 1 was equipped with a cone-shaped antenna, a highly directional helical antenna, four television cameras, and special extendable devices to impact the lunar soil for density measurements and mechanical property tests.
  • In an axial-mode helical antenna the direction of twist of the helix determines the polarisation of the radio waves : a left-handed helix radiates gain when receiving right-circularly-polarised signals, and vice versa.
  • In order to receive HRPT transmissions a high gain antenna is required, such as a small satellite dish, a helical antenna, or a dish tracking controller are required to steer the Azimuth-Elevation unit controlling the parabolic dish.