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 

                                                 F­_n =  (( nλd₁d₂ / (d₁ + d₂ ))^1/2

Here n is the nth Fresnel zone

F­­_{n  ­} 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 1^st 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 .