coastal refraction


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coastal refraction

[′kōs·təl ri′frak·shən]
(electromagnetism)
An apparent change in the direction of travel of a radio wave when it crosses a shoreline obliquely. Also known as land effect.

coastal refraction

coastal refractionclick for a larger image
Aircraft at A will get erroneous reading while that at B will have no error. Alternatively, A should utilize a beacon located near coast line.
One of the errors in a direction finder resulting from the change in the direction of travel of a radio ground wave as it passes from one medium to another (i.e., from land to sea or from sea to land). Also called land effect, shoreline effect, and shoulder effect. This effect can be minimized by use of coastal beacons, in which the radio beam will leave the coast at 90°, resulting in nil refraction.
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