User manual

Reference ILX34-AENWG ♦ Point I/O Platform
User Manual Wireless POINT I/O Adapter
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Page188of209 ProSoftTechnology,Inc.
 September19,2011
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6.5.2 Antenna Gain
Antennagainisameasureofhowstronglyanantennaradiatesinitsdirectionofmaximum
radiationintensitycomparedtohowstrongtheradiationwouldbeifthesamepowerwere
appliedtoanantennathatradiatedallofitspowerequallyinalldirections.Usingtheantenna
pattern,thegain
isthedistancetothefurthestpointonthepatternfromtheorigin.Foran
omnidirectionalpattern,thegainis1,orequivalently0dB.Thehighertheantennagainis,the
narrowerthebeamwidth,andviceversa.
Theamountofpowerreceivedbythereceivingantennaisproportionalto
thetransmitterpower
multipliedbythetransmitantennagain,multipliedbythereceivingantennagain.Therefore,the
antennagainsandtransmittingpowercanbetradedoff.Forexample,doublingoneantennagain
hasthesameeffectasdoublingthetransmittingpower.Doublingbothantennagainshasthe
sameeffectasquadrupling
thetransmittingpower.
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6.5.3 Antenna Polarity
Antennapolarizationreferstothedirectioninwhichtheelectromagneticfieldlinespointas
energyradiatesawayfromtheantenna.Ingeneral,thepolarizationiselliptical.Thesimplestand
mostcommonformofthisellipticalpolarizationisastraightline,orlinearpolarization.Ofthe
transmittedpowerthatreachesthereceiving
antenna,onlytheportionthathasthesame
polarizationasthereceivingantennapolarizationisactuallyreceived.Forexample,ifthe
transmittingantennapolarizationispointedintheverticaldirection(verticalpolarization,for
short),andthereceivingantennaalsohasverticalpolarization,themaximumamountofpower
possiblewillbe
received.Ontheotherhand,ifthetransmitantennahasverticalpolarizationand
thereceivingantennahashorizontalpolarization,nopowershouldbereceived.Ifthetwo
antennashavelinearpolarizationsorientedat45°toeachother,halfofthepossiblemaximum
powerwillbereceived.
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6.5.4 Whip antennas
Youcanusea1/2wavestraightwhipor1/2wavearticulatingwhip(2dBi)antennawithILX34‐
AENWGradios.Theseantennasarethemostcommontypeinusetoday.Suchantennasare
approximately5incheslong,andarelikelytobeconnectedtoaclientradio(connecteddirectly
tothe
radioenclosure).Theseantennasdonotrequireagroundplane.Articulatingantennasand
non‐articulatingantennasworkinthesameway.Anarticulatingantennabendsatthe
connection.
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