User's Manual
Table Of Contents
RF Integration
Rev 1.8.1 May.08 Proprietary and Confidential 17
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Note: The module shields must NOT be removed.
Antenna and cabling
Note: Values in this guide are
taken from the appropriate
product specification documents
(PSDs) (listed in
Related
documents
, page 8) — in the
case of a discrepancy between
this document and the relevant
PSD, use the value listed in the
PSD.
Whenselectingtheantennaandcable,itiscriticaltoRFperfor‐
mancetomatchantennagainandcableloss.
Choosing the correct antenna and cabling
Considerthefollowingpointsforpropermatchingofantennas
andcabling:
• Theantenna(andassociatedcircuitry)shouldhavea
nominalimpedanceof50
Ωwithareturnloss≤ 10dB
acrosseachfrequencybandofoperation.
• Thesystemgainvalueaffectsbothradiatedpowerand
regulatory(FCC,IC,CE,etc.)testresults.
Developing custom antennas
Considerthefollowingpointswhendevelopingcustom‐
designedantennas:
• AskilledRFengineershoulddothedevelopmenttoensure
thattheRFperformanceismaintained.
• Identifythebandsthatneedtobesupported,particularly
whenboththeMC57xxandMC87xxwillbeinstalledinthe
sameplatform.Inthiscase,youmaywanttodevelop
separateantennasformaximumperformance.
Determining the antenna’s location
Considerthefollowingpointswhendecidingwheretoputthe
antenna:
• AntennalocationmayaffectRFperformance.Althoughthe
moduleisshieldedtopreventinterferenceinmostapplica
‐
tions,theplacementoftheantennaisstillveryimportant—
ifthehostdeviceisinsufficientlyshielded,highlevelsof
broadbandorspuriousnoisecandegradethemodule’s
performance.
• Connectingcablesbetweenthemoduleandtheantenna
musthave50
Ωimpedance.Iftheimpedanceofthemodule
ismismatched,RFperformanceisreducedsignificantly.
• Antennacablesshouldberouted,ifpossible,awayfrom
noisesources(switchingpowersupplies,LCDassemblies,
etc.).Ifthecablesarenearthenoisesources,thenoisemay
becoupledintotheRFcableandintotheantenna.