Satellite Internet Access Limitation: Fresnel Zone

Oct 9
08:48

2012

Johnny Diaz

Johnny Diaz

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The radio signal width between any two antennas is not perfectly straight and uniform, as if it were a beam of light.

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Instead as the signal propagates away from the transmitting antenna,Satellite Internet Access Limitation: Fresnel Zone Articles it widens towards the center point between the two antennas and then narrows again as it approaches the receiving antenna. This is known as the Fresnel zone, in optics and radio communications (indeed, in any situation involving the radiation of waves, which includes electrodynamics, acoustics, and gravitational radiation), named for physicist Augustin-Jean Fresnel, a French engineer who contributed significantly to the establishment of the theory of  wave optics, one of a (theoretically infinite) number of concentric ellipsoids which define volumes in the radiation pattern of a (usually) circular aperture. 


It also limits the usefulness of satellite dish antennas in locations where there is extremely limited open sky for signal reception. The signal path through space must be clear not only for direct line of sight, but also for the expanding Fresnel zone, which may be several meters larger in diameter than the ground-based satellite dish.


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