Enterasys-networks ROAMABOUT RBT-1602 Manuel d'utilisateur télécharger pdf (Page 17)

Determining the Antenna Locations

RoamAbout Antenna Site Preparation and Installation Guide 1-5

Line of Sight

Theshapeoftheradiobeam,definedastheFresnelZone,iswidestinthemiddle.TheFresnel

ZoneisshownasthegrayareabetweentheantennasinFigure 1‐1.Theexactshapeandwidthof

theFresnelZoneisdeterminedbythedistancebetweentheantennaandfrequency

oftheradio

signal.

Theradiusoftheradiobeam,shownasthelowerhalfoftheFresnelZone,isthedistancefromthe

centerofthebeamoutwardinanydirection.Thelengthoftheradiusisnotbasedonthedatarate

andthetypeofantenna.

Figure 1-1 Fresnel Zone and Line of Sight Clearance

Ifa

significantpartoftheFresnelZoneisobstructed,aportionofradioenergyislost,resultingin

reducedperformance.Foroptimalperformance,ensurethattheantennaproductsyouchoose,in

combinationwiththeheightoftheantennainstallationaboveground,providesufficientclearance

toallowyourantennainstallationtocover

thedistancebetweenthetwosites.

Obstacleswithinthelineofsightcansignificantlyreducethedistanceandperformance.

Obstructionsincludeneighboringbuildings,trees,andpowerlines,asshowninFigure 1‐2.

Total Distance

Radius

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 91 92

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