a five element parasitic rotatable vertical yagi for 160 ... · • the array can be built around...
TRANSCRIPT
A Five Element Parasitic Rotatable Vertical Yagi for
160 meters JoelHarrison,W5ZN
2018DaytonHamventionAntennaForum
The Need for a New TX Array • 10yearsperfectingRXarraysatW5ZN
• 260DXCCcountriesconfirmedbutbecamestagnate• Thecountriesneededaremuchmoredifficulttowork
• NeededextraTXgainanddirectivitytoadvancemyDXstandingsfromArkansas
W5ZN
The Search for the Right Array at W5ZN • Spentwellovertwoyearsfrettingoverwhattodo• Revisitedthesectiononverticalarrayswithparasiticelementsin“LowBandDX’ing”• Chapter13,Section3.9,page13-39FifthEdition
• Studiedthedesignforabout2weeks• Literallybecameobsessedwiththisdesign
• K3LR’sversionisdescribed• TraveledtoK3LRtoseehisinstallation• FurtherdiscussionwithK3LRatSixMeterBBQinAustininSept2017
• BecameconvincedthiswastheperfectarrayfortheW5ZNstationW5ZN
Why a Vertical Yagi Array with Parasitic Elements Over a 4 Square? • ThearraycanbebuiltaroundanexistingsingleTXvertical
• Donotneedfullsizeelements
• ExistinglandareaaroundthesingleTXverticalcanbeutilized
• SamebasicgainandF/Bisrealizedin4rotatabledirection
• Verysimplefeedsystem.Nophasingorcomplicatedschemes.Theexistingmatchingnetworkonmysingleverticalisallthatisrequired
• Slightlysmallerelementfootprintthan4Square
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HorizontalPatterat20degreeselevation
25dBF/B5dBForwardGain
EquivalentForwardGainandF/B
Why a Vertical Yagi Array with Parasitic Elements Over a 4 Square?
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The Vertical Yagi Array with Parasitic Elements • PopularizedbyBillHohnstein,K0HA
• Comprisedof3ormoreverticalelementswithoneactivedrivenelementandtherestparasitic
• CurrentlyinuseatAA1K,VE3EJ,K3LR,NR5M&K9CT• AA1Khasa2ndDirectortoEuropeonhisarrayforatadmoregain
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• Toploadedverticalparasiticelementsareextremelyeffective
• ElementscanbeeasilysuspendedwithcatenaryropesfromtheexistingTXvertical
The Top Loaded Vertical Element
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The Top Loaded Vertical Element • Resonantwithashorterverticallength
• NoFarFieldhorizontalcomponentasthetoploadwireissymmetricaltoverticalwire.
• Slopingtoploadingwireis~65ft.
• Verticalwireis~75ft.
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Constructing the Array • Constructioneffortorganizedinto5Phases
1. PhysicalLayout2. RadialSystem
3. ElementConstruction&Erection
4. Tuning5. ParasiticArraySwitching
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Physical Layout • VerysimpleProcess–30minsorless
• Elementsspaced66ft.fromDrivenElement
• 4parasiticelementsspaced90degreesaroundadrivenelement
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Radial System • Themostcomplicatedandtimeconsumingpartoftheproject• ItisMOSTimportant!!!!
• Parasiticarrayshaveagreaterimpactfromapoorgroundsystem
• Elevatedradialssimplywon’twork• ON4UN’smodelingshowssignificantpatterndistortion
• Withaphasedarray(e.g.4Square)currentdistributionisforcedintoeachelement
• Propercurrentdistributionandthusgaininaparasiticelementisimpactedbygroundresistancesoaneffectiveradialsystemismandatory
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Radial System • Gainof3elementarrayasafunctionofgroundlossresistance
• CaseAisforadrivenelementwithafixed1Ωlossresistancebutwithvaryinggroundlossresistanceattheparasiticelements
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Radial System • 120radialsusedundereachelement
• Radialsaretiedtogetheratintersectingpoints
• 13.7miles(22KM)ofwireusedinradialsystem
0.18λ
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• W5ZNconstructionprocedure1. Install120radialsfromdriven
elementto48ft.perimeterwire
2. Installradialsfromeachelementthatintersect48ft.diameterperimeterwire
3. Installallradialsfromeachelementthatintersectthecrossbusswire
4. Installallremaining1/4λlengthradialstocompleteatotalof120ateachelement
Radial System
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Radial System • 48ft.diameterperimeterwire(#4solidcopper)arounddrivenelement
• 120radialsfromthedrivenelementtiedtothisperimeterwire
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Radial System • Perimeterwirelaidina48ft.diametercirclearounddrivenelement
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Radial System • Radialwiresfromthedrivenelementaresolderedtotheperimeterwire
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Radial System • Radialwiresfromeachelementthatintersecttheperimetercirclearesolderedtotheperimeterwire.
• Allconnectionsarethencoatedwithliquidtape
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Radial System • Someoftheradialwiresfromanelement.
• IdoNOTburyradialwires!
• Mowgrassveryshort(don’tscalp)andlayradialsontheground.Securewithradialstaples
• Newgrassgrowthinspringwillcoverthewires.
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Radial System • Youcanuseanysoundmethodforattachingradialswiresattheelements.IprefertheDXEngineeringRadialPlates
• Icrimp&soldertheradialwirestoringterminallugsthencoatthejointwithliquidtape.
• IusePenetroxtomaintainagoodconnectionovertimeandpreventgalvaniccorrosionwithdifferentmetalsoftheplateandterminals
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Radial System • Completedradialsystemunderoneelement
• Iusebiodegradablestaplestoholdradialsinplacepriortonewgrassgrowth
• Totalradialsystemarea<2acres
• Totalconstructiontimeforradialfield-4weeks
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Element Construction • Eachelementwillneedtofunctionasadirectorandareflectorfordifferentdirections
• Toaccomplishthis,theelementisswitcheddirectlytotheradialsystemasadirector,orthrougha4uHinductortofunctionasareflector
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Element Construction & Erection • Vertical&toploadexactlengthsareachievedbytrial&error
• Buildoneelement,erectitandthentunetothetargetfrequency.Theremainingelementsshouldbethesame.
• Usearopeandpulleyonthefirstelementunlessyouenjoyclimbing135ftmultipletimes!!!!
• Distancefromdrivenelementtofirstinsulatoronthetoploadingsegmentwillbeapprox.45ft.
• Distancefromdrivenelementtoendtiepointwillbeapprox.265ft.
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Element Construction
ON4UNModel
K3LRSystem
W5ZNInitial
W5ZNFinal
TopLoad 64.7ft. 58.3ft. 58.3ft. 65ft.Vertical 75.5ft. 64.2ft. 64.2ft. 75ft.Director 1935KHz 1904KHz 2070KHz 1904KHzReflector 1778KHz 1800KHz 1950KHz 1800KHz
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Tuning - Each Element • Connectanantennaanalyzerbetweentheverticalelementandtheradialsystem
• Switchintheverticalwiredirectlytotheradialsandadjustthelengthtothedesireddirectorfrequency
• Switchintheverticalwireandinductortotheradialsandadjusttheturnsspacingontheinductorforthedesiredreflectorfrequency
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• Thesystemhasan“Omni”modewhenallfourparasiticelementsarefloatinghoweverthereisadifferenceinfeedpointimpedancecharacteristicswhenthearrayisactive.• TheOmnimodesprimarypurposeisRXsignalcomparison
• MakefinalSWRtuningadjustmentswiththe“array”active
• Shouldrealizeaverylow1.1:1SWRwitha1.5:1bandwidthofapproximately40KHz
Tuning – As an Array
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Tuning – As an Array
40KHzBandwidthFinalAdjustmentProduceda1.1:1SWRat1.825MHzW5ZN
Tuning – Fine Tweaking • Driveoutapproximately1to2milesineachofthefourdirectionswithalowlevelsignalsource
• AdjustformaximumF/B–Procedure:1. Drivetotheoppositedirection,e.g.SWfortheNEdirection2. SelecttheNEDirectionforthearray3. Transmitfromthedistantlowlevelsignalsource4. Adjusttheturnsspacingonthereflectorelementinductorforlowestsignal
(maxF/B)
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Array Switching
• GregOrdy,W8WWVdesignedacircuitboardforK3LR
• Onceassembleditcontainstworelaysandinductor
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Array Switching • A5positionswitchboxisusedtoswitcharraydirection
• Foronedirection,relay1isenergizedontheforwarddirectorelementandrelay2ontherearreflectorelement
• Unusedelementsarenotconnectedfromtheirradialsand“float”
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Array Switching • Switchboardinstalledatoneelement
• Plasticboxhousingusedateachparasiticelement
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Array Switching
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What the Heck is That Roll of Cable? • 160meter1/4λshortedstub
• The160arrayisclosetoW5ZN’s80meter4Squarearray
• Invisibleon160meters• Stubisinvisibleon160meters,appearsasan“open”
• On80metersthisis1/2λandappearsasa“short”atthefeedpoint
• Eliminates/minimizesinteractionbetweenthetwoarrays
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• TheSoutheast160meterelementisonly60ft.fromthenortheast80meter4Squareelement
What the Heck is That Roll of Cable?
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On-the-Air Results • Realize5dBforwardgain• F/B~25dB• RBNindicatessignificantimprovementoversinglevertical
• Significantimprovementinpileups!
• 9MØWSpratly160meteroperatorJeff,K1ZM:“YoursignalwasbetterthanMOST!AboutRST339whichmaynotsoundLOUD-butcomparedtoalltheothersatRST219,youwereLOUD(HIHI)”
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Acknowledgements • TimDuffy,K3LR
• JonZaimes,AA1K
• LarryBurke,K5RK
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