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  2. Line-of-sight propagation - Wikipedia

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

    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. The rays or waves may be diffracted ...

  3. Line of sight - Wikipedia

    en.wikipedia.org/wiki/Line_of_sight

    The line of sight, also known as visual axis or sightline (also sight line), is an imaginary line between a viewer/ observer / spectator 's eye (s) and a subject of interest, or their relative direction. [1] The subject may be any definable object taken note of or to be taken note of by the observer, at any distance more than least distance of ...

  4. Radial velocity - Wikipedia

    en.wikipedia.org/wiki/Radial_Velocity

    The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity onto the relative direction or line-of-sight (LOS) connecting the two points.

  5. Horizon - Wikipedia

    en.wikipedia.org/wiki/Horizon

    The curvature of the horizon is easily seen in this 2008 photograph, taken from a Space Shuttle at an altitude of 226 km (140 mi).. The horizon is the apparent curve that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body.

  6. Fresnel zone - Wikipedia

    en.wikipedia.org/wiki/Fresnel_zone

    A Fresnel zone (English: / freɪˈnɛl / fray-NEL), named after physicist Augustin-Jean Fresnel, is one of a series of confocal prolate ellipsoidal regions of space between and around a transmitter and a receiver. The primary wave will travel in a relative straight line from the transmitter to the receiver. Aberrant transmitted radio, sound, or ...

  7. Over-the-horizon radar - Wikipedia

    en.wikipedia.org/wiki/Over-the-horizon_radar

    The frequency of radio waves used by most radars, in the form of microwaves, travel in straight lines.This generally limits the detection range of radar systems to objects on their horizon (generally referred to as "line of sight" since the aircraft must be at least theoretically visible to a person at the location and elevation of the radar transmitter) due to the curvature of the Earth.

  8. Proportional navigation - Wikipedia

    en.wikipedia.org/wiki/Proportional_navigation

    This factor is N. Proportional navigation (also known as PN or Pro-Nav) is a guidance law (analogous to proportional control) used in some form or another by most homing air target missiles. [1] It is based on the fact that two vehicles are on a collision course when their direct line-of-sight does not change direction as the range closes. PN ...

  9. Orbital inclination - Wikipedia

    en.wikipedia.org/wiki/Orbital_inclination

    The inclination of exoplanets or members of multi-star star systems is the angle of the plane of the orbit relative to the plane perpendicular to the line of sight from Earth to the object. [5] An inclination of 0° is a face-on orbit, meaning the plane of the exoplanet's orbit is perpendicular to the line of sight with Earth.