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  2. Line-of-sight propagation - Wikipedia

    en.wikipedia.org/wiki/Line-of-sight_propagation

    Line of sight (LoS) propagation from an antenna. Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. [1] Electromagnetic transmission includes light emissions traveling in a straight line.

  3. Atmospheric duct - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_duct

    Atmospheric ducting is a mode of propagation of electromagnetic radiation, usually in the lower layers of Earth’s atmosphere, where the waves are bent by atmospheric refraction. [2] In over-the-horizon radar , ducting causes part of the radiated and target-reflection energy of a radar system to be guided over distances far greater than the ...

  4. Vertical and horizontal (radio propagation) - Wikipedia

    en.wikipedia.org/wiki/Vertical_and_horizontal...

    In radio propagation, horizontal plane is used to plot an antenna's relative field strength in relation to the ground (which directly affects a station's coverage area) on a polar graph. Normally the maximum of 1.000 or 0 dB is at the top, which is labeled 0 o , running clockwise back around to the top at 360°.

  5. Radio propagation - Wikipedia

    en.wikipedia.org/wiki/Radio_propagation

    Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]

  6. High-frequency Active Auroral Research Program - Wikipedia

    en.wikipedia.org/wiki/High-frequency_Active...

    The HAARP project directs a 3.6 M W signal, in the 2.8–10 MHz region of the HF band, into the ionosphere. The signal may be pulsed or continuous. Effects of the transmission and any recovery period can be examined using associated instrumentation, including VHF and UHF radars, HF receivers, and optical cameras. According to the HAARP team ...

  7. Event Horizon Telescope - Wikipedia

    en.wikipedia.org/wiki/Event_Horizon_Telescope

    The Event Horizon Telescope (EHT) is a telescope array consisting of a global network of radio telescopes.The EHT project combines data from several very-long-baseline interferometry (VLBI) stations around Earth, which form a combined array with an angular resolution sufficient to observe objects the size of a supermassive black hole's event horizon.

  8. Index of radio propagation articles - Wikipedia

    en.wikipedia.org/wiki/Index_of_radio_propagation...

    radiation belt - radiation scattering - radio blackout - Radio direction finder - radio frequency - radio horizon - radio propagation - radio propagation beacon - radio propagation model - Radio Society of Great Britain - ray tracing (physics) - Rayleigh fading - Rayleigh–Taylor instability - rain fade - reference distance - relative ...

  9. Radio wave - Wikipedia

    en.wikipedia.org/wiki/Radio_wave

    So radio waves directed at an angle into the sky can return to Earth beyond the horizon; this is called "skip" or "skywave" propagation. By using multiple skips communication at intercontinental distances can be achieved. Skywave propagation is variable and dependent on atmospheric conditions; it is most reliable at night and in the winter.