User's Manual

MC5720/5725/8755/8765 Hardware Integration Guide
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Shielding
ThemoduleisfullyshieldedtoprotectagainstEMIandto
ensurecompliancewithFCCPart15‐“RadioFrequency
Devices”(orequivalentregulationsinotherjurisdictions).
Note: The module shields must NOT be removed.
Antenna and cabling
Whenselectingtheantennaandcable,itiscriticaltoRFperfor‐
mancetomatchantennagainandcableloss.
Choosing the correct antenna and cabling
Considerthefollowingpointsforpropermatchingofantennas
andcabling:
• Theantenna(andassociatedcircuitry)shouldhavea
nominalimpedanceof50 Ωwithareturnloss ≤ 10 dB
acrosseachfrequencybandofoperation.
• Thesystemgainvalueaffectsbothradiatedpowerand
regulatory(FCC,IC,CE,etc.)testresults.
Developing custom antennas
Considerthefollowingpointswhendevelopingcustom‐
designedantennas:
• AskilledRFengineershoulddothedevelopmenttoensure
thattheRFperformanceismaintained.
• Identifythebandsthatneedtobesupported,particularly
whenboththeMC5720/5725andMC8755/8765willbe
installedinthesameplatform.Inthiscase,youmaywantto
developseparateantennasformaximumperformance.
Determining the antenna’s location
Considerthefollowingpointswhendecidingwheretoputthe
antenna:
• AntennalocationmayaffectRFperformance.Althoughthe
moduleisshieldedtopreventinterferenceinmostapplica‐
tions,theplacementoftheantennaisstillveryimportant—
ifthehostdeviceisinsufficientlyshielded,highlevelsof
broadbandorspuriousnoisecandegradethemodule’s
performance.
• Connectingcablesbetweenthemoduleandtheantenna
musthave50 Ωimpedance.Iftheimpedanceofthemodule
ismismatched,RFperformanceisreducedsignificantly.
• Antennacablesshouldberouted,ifpossible,awayfrom
noisesources(switchingpowersupplies,LCDassemblies,