System Description

(7)
Theantennamountingshouldbecapableofdissipatingatleast60Wofheatfromtheantenna
wheninuse.
–Theheatloadisprimarilythroughthebottommetalsurfaceoftheantenna.
–Ensurethatthemountingeitherconductstheheatawayfromtheantennaorthatthereis
sufcientairowoverthebottomoftheantennatotaketheheatout.
(8)
Theantennashouldbemountedon,andelectricallybondedto,agroundplane.
–Thegroundplaneaffectstheantennagainpattern.Thelargerthegroundplaneisthemore
reliablethesatellitesignalwillbe,particularlyforlowersatelliteelevations.
–Theminimumgroundplanesizeshouldbe18cminwidthby30cminlength.
–Thegroundplaneshouldbeaconductivesurface,levelwiththebottomsurfaceofthe
antenna.
–Thegroundplaneshouldhavearesistivityof6μΩ/cmorbetter.
–Wherethegroundplaneleavestheplaneofthebottomoftheantenna,forexamplefollowing
thecurveofafuselage,itsefciencywilldrop.
(9)TheantennahasaprovisionformountingonthetopsurfaceofaUAVfuselage
–TheholefortheRFconnectorshouldbe0.63in.(16mm)diameter.
(10)TheO-ringforsealingthefuselageagainstwateringressshouldbettedontheantenna.
(11)
OnmetalskinnedUAV’sthethermalandgroundplanerequirementsmaybemetiftheantenna
isthermallyandelectricallybondedtothesurfaceoftheaircraft.Ifthesurfacerequires
preparationtoachieveelectricalbond,refertoSAEAR1870Section5.
–Theelectricalbondbetweentheantennaandlocalstructuremustbelessthanorequalto3
milliohmdirectcurrent(DC)resistance.Complianceshouldbeveriedusingacalibrated
milliohmmeter.
–AnypaintremovedfromtheUAVskintomeetthebondingrequirementshouldhavea
corrosionresistanceprotectivecoatingappliedthatmeetsMIL-DTL-5541TYIICL3or
MIL-C-5541CL3,commonlyknownasAlodine.
–Adoublerplatefabricatedbytheinstallerisnormallyused.
(12)
OncompositeUAVs,additionalstructuremayneedtobeaddedtomeettheantennathermal
andgroundplanerequirements.
–Theelectricalbondbetweentheantennaandgroundplanemustbelessthanorequalto3
milliohmdirectcurrent(DC)resistance.Complianceshouldbeveriedusingacalibrated
milliohmmeter.
–2000seriesaluminiumorcopperisrecommendedtomeetthegroundplaneconductivity
requirements.
–Normally,carbonbrestructureshavetoohighathermalandelectricalresistancetomeet
thethermalandgroundplanerequirements.
(13)
Theantennashouldbesecuredtotheairframeusingthe4mountingscrewssupplied
(MS24693-C279:10-32UNF-2AX1.50longcrossrecessedathead100°,SST).
Page12
18 Feb 2021
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SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
SMALL SATCOM