Fresnel Zone

This definition page has been automatically generated. You can help ExoDictionary by expanding, updating, or correcting it.

This autostub has not yet had its initial copyediting proof and may contain significant formatting and even factual errors. You can improve Exodictionary by cleaning up the page markup and verifying that the definition is correct and then removing this tag.

This autostub has not yet had its initial categorization proof and may be categorized incorrectly. You can improve Exodictionary by removing inappropriate categories and then removing this tag.

Fresnel Zone </dt>
Any one of the array of concentric surfaces in space between transmitter and receiver (or between radar antenna and target) over which the increase in distance over the straight line path is equal to some multiple of one-half wavelength. Also called half-period zone. See interference region. </dd>
''Outside of rather unusual multipath transmission of radio energy in the free atmosphere, Fresnel zones are of importance primarily in studying the interference lobes produced by the interaction of a direct and a surface-reflected wave. Thus, for a given path, reflected radio energy arriving at the receiver from any point along any of the surface Fresnel zones will be some multiple of 180� out of phase with the direct wave, thereby producing destructive or constructive interference as the multiple is odd or even, respectively. </dd>

References

This article is based on NASA's Dictionary of Technical Terms for Aerospace Use