Search results
Results from the WOW.Com Content Network
See also Non-line-of-sight propagation for more on impairments in propagation. It is important to take into account the curvature of the Earth for calculation of line-of-sight paths from maps, when a direct visual fix cannot be made. Designs for microwave formerly used 4 ⁄ 3 Earth radius to compute clearances along the path.
To set a sight line 13 feet (4.0 m) above the water, and thereby reduce the effects of atmospheric refraction. To add a pole in the middle of the length of canal that could be used to see the "bump" caused by the curvature of the Earth between the two end points.
Unfortunately there are two different definitions of this coefficient. One is the ratio of the radius of the Earth to the radius of the line of sight, [27] the other is the ratio of the angle that the line of sight subtends at the center of the Earth to the angle of refraction measured at the observer. [28]
s is along the surface of the Earth, d is the straight line distance, and ~d is the approximate straight line distance assuming h << the radius of the Earth, 6371 km. In the SVG image, hover over a graph to highlight it. If the observer is close to the surface of the Earth, then it is valid to disregard h in the term (2R + h), and the formula ...
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.
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]
The visibility from an elevated observation point down to the surface of the sea can be calculated using the Pythagorean theorem, since the line of sight and the radius of the Earth form the two legs of a right triangle. The height of the elevated point plus the Earth radius form its hypotenuse. If both the eyes and the object are raised above ...
When atmospheric refraction is considered, ray tracing becomes necessary (Kivalov 2007), and the absolute air mass integral becomes [7] = where is the index of refraction of air at the observer's elevation above sea level, is the index of refraction at elevation above sea level, = +, = + is the distance from the center of the Earth to a ...