Base Station Antenna Systems 2008 Product Selection Guide - AVW

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Applications/Engineering NotesBase Station Antenna Materials and Mechanical Characteristicsundue change, resistance to ultravioletradiation from sunlight and to certain gases,mechanical strength, mechanical impactresistance, and workability in machining ormolding. Depending on the application, certainof the newer urethanes, epoxies, and syntheticresins meet most of the basic requirements atreasonable cost.Coaxial and PrintedCircuit Feed NetworksElement feed networks are generally coaxialharnesses, printed circuits, air dielectricstripline or a hybrid combination of all three.A feed harness or “feed” includes thetransmission line (generally coaxial) from theantenna input terminal to the actual connectionon the radiator(s). This includes all matchingtransformers and interconnections betweenradiators such as tees or multi-junctionconnections.Mechanical strain must be avoided on thecables and connectors. The inner conductors ofsmall cable such as RG-141 should be givenrelief from direct strain. Sharp bends should beavoided in all cables.Printed circuit feed networks are more oftenemployed above 800 MHz where they canfacilitate elevation beam shaping with uppersidelobe suppression and null fill. Often thefeed network and the radiating elementscan occupy the same printed circuit board.Whenever printed circuit boards are employedthe use of conformal coating is mandatoryto protect the circuits from environmentalcontamination (moisture, corrosion, etc.).Air Dielectric StriplinesAir dielectric stripline-feed networks providethe lowest loss technology available. The feednetworks are formed from a single pieceof material, thus minimizing RF connectionpoints. The use of high quality fabricationtechniques yields very repeatable patternsand performance. By careful design, thistechnology can also facilitate the same typeof beam shaping provided by printed circuitboard technology.Mechanical CharacteristicsWhile electrical characteristics determineantenna performance, mechanicalcharacteristics are equally important inoverall considerations of the antenna systemsince they largely determine the life andserviceability.Station antennas often are mounted on talltowers where the expense of installation mayequal or exceed the price of the antenna itself.It is important, therefore, that the antenna becapable of withstanding the environmentalconditions of wind and ice without failure, andalso be able to resist the weathering effect ofatmospheres it is normally subjected to.Wind and IceSince antennas are installed in all areas undervarious conditions of wind and ice, it is difficultto set a value of wind and ice loading thatwill satisfy the maximum or severe conditionswithout overdesigning with unduly high cost forthose areas where severe conditions of windand ice as encountered on some mountaintopsmust be handled by specially rugged designs.The force (F) or load that wind of a givenvelocity exerts on an antenna surface isV 2F = A ——— C d , where2A—Antenna area projected on a surfaceperpendicular to the vector of wind velocity—Air densityV—Wind velocityCd—Drag coefficient, for antennas dependson cross section shape, ratio of Length/Width(Depth) and Reynolds numberWind load can also be calculated usingequivalent flat plate area (A ƒp , see product datasheets available on the Andrew web site atwww.andrew.com) per formula shown below:V 2F = A ƒp ——— C d ƒp , where2drag coefficient of flat plateCd ƒp = constant = 2.2The minimum design criteria for windload should be to handle true wind velocitiesof 100 mph (161 km/hr) without ice andwhen feasible the design should be capableof handling stronger winds because manyhurricane areas are subjected to winds inexcess of 100 mph (161 km/hr). Where icingconditions are prevalent a separate loadingshould be calculated for 0.5 in (12.7 mm)radial ice with maximum wind velocity reducedbecause with such icing it is not usual to havehurricane force winds. The area should be themaximum area that the antenna could presentto the wind, figuring that the wind could comefrom any direction.Connectors and TerminationType N and 7–16 DIN connectors are suitablefor use in mobile radio communications;however, UHF connectors should not beused above 300 MHz. For the demandingintermodulation (IM) specifications required byhigh-capacity systems, the 7–16 DIN Family ofconnectors is strongly recommended.As in the case of fittings, there are preferencesfor antenna termination. Some users like theconnector rigidly attached to the antennasupport, while others prefer a flexible cablewith fittings attached to its end. In eithercase, some flexible lead is desirable betweenthe antenna and most transmission lines tofacilitate installation and test. Andrew offers aselection of factory fabricated jumper cables —both standard and superflexible—to interfacebetween tower mounted components.Hardware and MountingSmall hardware such as bolts, nuts, and rivetsused for attachment of radiating elementsor support members should be of sufficientstrength and resistant to corrosion. Stainlesssteel meets these requirements and isdesirable for many applications. High strengthaluminum alloys also are suitable and offersome advantage for aluminum-to-aluminumconnection where galvanic corrosion is aproblem.Andrew Wireless Solutions www.andrew.com131
Applications/Engineering NotesBase Station Antenna Materials and Mechanical CharacteristicsIsolation in dBIsolation in dBIsolation Provided by Antenna SeparationATTENUATION PROVIDED BY VERTICAL SEPARATION OF DIPOLE ANTENNAS7060504030202000 MHz850 MHz450 MHz160 MHz101 2 3 5 10 20 30 50 100(0.3) (0.61) (0.91) (1.52) (3.05) (6.1) (9.14) (15.24) (30.48)Antenna Spacing in Feet (Meters)(Measured between antenna centers)75 MHz40 MHzThe values indicated by these curves are approximate because of coupling that exists between the antenna and transmission line.Curves are based on the use of half-wave dipole antennas. The curves will also provide acceptable results for gain type antennas if(1) the spacing is measured between the physical center of the tower antennas and (2) one antenna is mounted directly above theother, with no horizontal offset (exactly collinear). No correction factor is required for the antenna gains.ATTENUATION PROVIDED BY HORIZONTAL SEPARATION OF DIPOLE ANTENNAS8070605040302000 MHz850 MHz450 MHz150 MHz70 MHz50 MHz30 MHzHeavy hardware such as clamps, orientationmounts and offset brackets, should be steel,protected with hot dip galvanize finish, or castaluminum—depending on the application.Heavy directive arrays should incorporateinto the mount a convenient means oforientation with positive position locking.Clamps and mounts should be heavy duty inorder to transfer the full antenna load to thesupport tower or mast.Stainless steel locking bands of the radiatorhose type are very suitable for manyattachments provided that they are properlyapplied. The draw-up screws should alwaysbe positioned so as to draw down against afirm member (preferably round) in order toforce locking and holding of the screw to theband slots. Properly applied, these clampingbands are extremely strong and will maintainclamping force indefinitely. They offer aconvenient means of fastening to various sizesand shapes of towers and masts.Painting Base Station AntennasTo help antennas blend into the backgroundand make zoning easier, many customersdesire to paint the entire antenna. This can beeasily accomplished if a non-metallic basedpaint is used and smooth surfaces are slightlyroughed for better adhesion. For moreinformation please visit our website atwww.andrew.com/products/antennas/bsaand select BSA Technical Literature.2010 20 30 50 100 200 300 500 1000(3.05) (6.1) (9.14) (15.24) (30.48) (60.96) (91.44) (152.4) (304.8)Antenna Spacing in Feet (Meters)Curves are based on the use of half-wave dipole antennas. The curves will also provide acceptable results for gain type antennas if(1) the indicated isolation is reduced by the sum of the antenna gains and (2) the spacing between the gain antennas is at least 50 ft.(15.24 m) (approximately the far field).132Andrew Wireless Solutions www.andrew.com
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Base Station Antenna SystemsPRODUCT
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A Clear AdvantageAround the globe,
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Andrew Base Station Antenna (BSA) S
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Andrew Offers You a Complete Line o
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Base Station Antenna Systems Around
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ServicesPlanning SoftwareAASP—the
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Terms and ConditionsWarranty Inform
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Dual BandFeatures and BenefitsDualP
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Dual Band806-960/1710-2180 MHz60-75
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Notes18Andrew Wireless Solutions w
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1800/1900/UMTSFeatures and Benefits
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1800/1900/UMTSSingle Band Sector Ba
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1800/1900/UMTS1710-1880 MHz80-95°
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1800/1900/UMTS1710-2180 MHz80-95°
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1800/1900/UMTS1850-1990 MHz60-75°
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1800/1900/UMTS1850-1990 MHz80-95°
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1800/1900/UMTS1920-2180 MHz80-95°
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700/800/900 MHzFeatures and Benefit
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700/800/900 MHzSingle Band Sector B
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700/800/900 MHz806-896 MHz30 30 30
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700/800/900 MHz806-896 MHz80-95° H
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700/800/900 MHz806-960 MHz80-95° H
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700/800/900 MHz870-960 MHz60-75° H
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WiMAXFeatures and BenefitsSector An
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WiMAXSingle Band Sector Base Statio
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30-512 MHzFeatures and BenefitsGrou
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30-512 MHz30-174 MHz60-75° Horizon
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30-512 MHz406-512 MHz60-75° Horizo
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Teletilt ® Remote Electrical Downt
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Page 97 and 98: Concealment SolutionsOverview Micro
Page 99 and 100: Concealment SolutionsMicro AcCELLer
Page 101 and 102: Concealment SolutionsAntenna Concea
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Page 115 and 116: Applications/Engineering NotesOverv
Page 117 and 118: Applications/Engineering NotesBasic
Page 119 and 120: Applications/Engineering NotesAnten
Page 131: Applications/Engineering NotesBase
Page 135 and 136: Notes134Andrew Wireless Solutions
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