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  2. Near vertical incidence skywave - Wikipedia

    en.wikipedia.org/wiki/Near_Vertical_Incidence...

    An NVIS antenna configuration is a horizontally polarized (parallel with the surface of the earth) radiating element that is from ⁠ 1 / 20 ⁠ th wavelength to ⁠ 1 / 4wave above the ground. The optimum height of such an antenna is about ⁠ 1 / 4 ⁠ wavelength, and high angle radiation declines only slightly for heights up to about ...

  3. Antenna types - Wikipedia

    en.wikipedia.org/wiki/Antenna_types

    Paradoxically, every antenna of any type, shorter than ~ ⁠ 1 / 10 ⁠ wave in its longest dimension is approximately isotropic, but no real antenna can ever be exactly isotropic. An antenna that is exactly isotropic is only a mathematical model, used as the base of comparison to calculate either the directivity or gain of real antennas.

  4. Skywave - Wikipedia

    en.wikipedia.org/wiki/Skywave

    On October 10, the Third National Radio Conference made three shortwave bands available to U.S. amateurs [8] at 80 meters (3.75 MHz), 40 meters (7 MHz) and 20 meters (14 MHz). These were allocated worldwide, while the 10-meter band (28 MHz) was created by the Washington International Radiotelegraph Conference [ 9 ] on 25 November 1927.

  5. Waveguide (radio frequency) - Wikipedia

    en.wikipedia.org/wiki/Waveguide_(radio_frequency)

    In radio-frequency engineering and communications engineering, a waveguide is a hollow metal pipe used to carry radio waves. [1] This type of waveguide is used as a transmission line mostly at microwave frequencies, for such purposes as connecting microwave transmitters and receivers to their antennas, in equipment such as microwave ovens, radar sets, satellite communications, and microwave ...

  6. Omnidirectional antenna - Wikipedia

    en.wikipedia.org/wiki/Omnidirectional_antenna

    The quarter-wave monopole, the most compact resonant antenna, may be the most widely used antenna in the world. The five-eighth wave monopole – length 0.625 λ, or ⁠ 5 / 8 ⁠ of a wavelength – is also popular, since at that length monopoles direct the greatest proportion of their radiated power horizontally, hence the best use of ...

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  9. Whip antenna - Wikipedia

    en.wikipedia.org/wiki/Whip_antenna

    The length of a whip antenna is determined by the wavelength of the radio waves it is used with. Their length varies from compact electrically short antennas ⁠ 1 / 10 ⁠ wavelength long, up to ⁠ 5 / 8 ⁠ wavelength to improve directivity. The most common type is the quarter-wave whip, which is approximately ⁠ 1 / 4 ⁠ wavelength long.