Saturday, 16 June 2012

Fresnel Zone

FRESNEL ZONE
Fresnel zone is the primary factor while doing the LOS surveys for radio communication links.
After calculating the 1st Fresnel zone 60% of the radius is calculated which must be clear for reliable radio communication.
Fresnel Zone is calculated by the formula 
                                                 F­n =  (( nλd1d2 / (d1 + d2 ))1/2
Here n is the nth Fresnel zone
F­­n  ­ is the radius of nth Fresnel zone.
λ is the wavelength of frequency used.
d 1 and d2 are the distance from transmitter and receiver in the path LOS between transmitter and receiver.


For LOS communication only 60 % of 1st Fresnel zone calculated  and rest are just ignored .
If there is any obstruction in the 60% of the first Fresnel zone the radio wave reflecting from the obstacle may arrive at out of phase and hence may cause the interference .

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