- Fresnel zone
In
optics andradio communications, a Fresnel zone (pronounced "FRA-nel Zone"), named for physicistAugustin-Jean Fresnel , is one of a (theoretically infinite) number of concentricellipsoid s of revolution which define volumes in theradiation pattern of a (usually) circular aperture. Fresnel zones result fromdiffraction by the circular aperture. [where,
Fn = The nth Fresnel Zone radius in metres
d1 = The distance of P from one end in metres
d2 = The distance of P from the other end in metres
lambda = The wavelength of the transmitted signal in metres
The cross section radius of the first Fresnel zone is the highest in the center of the RF LoS which can be calculated as:
:r = 72.05 sqrtD} over {4 f
where
* "r" =radius in feet
* "D" = total distance inmile s
* "f" = frequency transmitted inGigahertz .Or even:
:r = 17.32 sqrtD} over {4 f
where
* "r" = radius in metres
* "D" = total distance inkilometres
* "f" = frequency transmitted in gigahertz.ee also
*
Augustin-Jean Fresnel
*Diversity scheme
*Fresnel integral
*Fresnel number
*Fresnel diffraction
*Microwave
*Near field
*Path loss
*Rain fade
*Weissberger's Model
*Zone plate References
External links
* [http://wisp-router.com/wirelesscalculators.php#fresnel FEN Fresnel Zone Calculator]
* [http://www.maxstream.net/support/knowledgebase/article.php?kb=90 More Fresnel Zone Details]
* [http://www.searchanddiscovery.net/documents/geophysical/sheriff/index.htm R.E. Sherriff, Understanding the Fresnel zone]
* [http://www.tapr.org/ve3jf.dcc97.html VHF/UHF/Microwave Radio Propagation: A Primer for Digital Experimenters]
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