User's Manual Part 2

Human Exposure to RF
InterReach Fusion Wideband Installation, Operation, and Reference Manual Page 207
D-620616-0-20 Rev H • TECP-77-044 Issue 7 • May 2013 © 2013 TE Connectivity Ltd.
HUMANEXPOSURETORF
TheU.S.FederalCommunicationsCommission(FCC)hasdevelopedguidelinesforevaluationof
humanexposuretoRFemissions.TheguidelinesincorporatelimitsforMaximumPermissible
Exposure(MPE)forpowerdensityoftransmittersoperatingatfrequenciesbetween300kHzand
100GHz.Limitshavebeensetforportable,mobile,andfixedequipment.TEproductsfallinthe
categoryoffixedequipment;productsintendedtobepermanentlysecuredandexposuresare
evaluatedfordistancesgreaterthan20cm(77/8”).Portabledevicesfallintoexposuresofless
than20cm,areSARevaluationsareused.
Antennagainisrestrictedto1.5
WERP(2.49WEIRP)inordertosatisfyRFexposurecompliance
requirements.Ifhigherthan1.5WERP,routineMPEevaluationisneeded.Theantennasshould
beinstalledtoprovideatleast20cmfromallpersonstosatisfyMPErequirementsofFCCPart2,
2.1091.
BasicMPEevaluationisperformedbytakingthemaximumpoweroutputofthe
equipment,the
gainoftheantennatobeused,anddistancefromtheantenna,referencedinFCCOETBulletin65
“EvaluationCompliancewithFCCGuidelinesforHumanExposuretoRadioFrequencyforElectric
Fields”.
TEproductstransmitwellbelowtheFCCpowerdensitylimits.FCCdefinesp
oweroutputlimits
at20cmdistanceforvariousfrequencyranges:
• Ov
er300mHzto1.5GHzthelimitisdeterminedbyfrequency/1500
• Above
1.5GHzthelimitis1mW/cm2
Thebasicequationfordeterminingpowerdensityis:
S = PG / 4R
2
WhereSispowerdensityinmW/cm2
PG,
thetransmittedpowerfromtheantennaidentifiedasEIRP(EquivalentIsotropicallyRadiated
Power),istheproductofpoweroutputofdeviceandantennagain,inmW.
Risthedistanc
eofinterestfromtheantenna.
TypicalInstallationExample:
Assuminganantennaisplacedona10footceiling,foraperson6
feettall,thedistancefrom
antennatobodyis4feet(112cm.).
ForaPCS1900remoteunit,themaximumpoweroutput,ac
cordingtothepowertablein
Section6.3MaximumOutputPowerperCarrier6‐4,is16.5dB.
Assuminga7dBiantennaisused,PGinth
eequationisequalto23.5dB(224mW)EIRP.
UsingS=PG/4
R
2
S=224/(4x3.14)x(122)
2
=0.001mW/cm
2
Also,assumingaminimumdistanceof20cmaccordingtoFCCregulations:
S=224/(4x3.14)x(20)
2
=0.04mW/cm
2