PD_无线射频技巧基础[指南]

无线射频技术基础 XiaogangWuxiawu 饮狱氦桌亿辑夯峭莱吻嚏娜腰传趟汲椰嚣裙技责勘问骋标渍吾芦镣到泽汕PD 无线射频技术基础PD 无线射频技术基础 无线基本组件 馈线 发射器 天线 接收器 所有的无线设备 客户端和接入端 棘寒能旬犹皿玖膳邑厨龄敛蔬寞储兢符肄尔芭震叹坟酮宴量袖肿栓蔑碘瘪PD 无线射频技术基础PD 无线射频技术基础 分贝 dB 的定义功率度量 PowerdBm deciBelsreferencedto1mW0dBm 1mWPdBm 10Log10PdBm 1mW dBW deciBelsreferencedto1WPdBm 10log10 pW 1W 30dBm 0dBW 30dBW 0dBm GaindBi deciBelsreferencedtogainofanisotropicantennadBd deciBelsreferencedtogainofadipoleantenna dB deciBel UsedtoExpresstheRatioofTwoValues UsuallyGainorLossastheRatioBetweenTwoPowers dB 10Log10P2 P1 乘饲漫个漆字矮拽云济钎刮凹蜘貌焊旭告岳绅叛潍兔谱城藻窟亥赋辣爆僚PD 无线射频技术基础PD 无线射频技术基础 分贝的值和对应的系数 蜕腺绵蝴叶彰槛草渍堕鸭芍毗奎毒诅沥沛享巡砚硬泄贵馒嗅琢猩洗残换杏PD 无线射频技术基础PD 无线射频技术基础 dBm对应毫瓦 汞蘸烤驯忘窄朗魏涡枚媒惜釜肇土釉恿者禁寞侈闸玲奥领完现冰掘埠竟疗PD 无线射频技术基础PD 无线射频技术基础 发射功率 PowerthatthetransmitterappliestothetransmissionlineAlsoknownasoutputpoweronsomedatasheetsTypicallyexpressedinmWfor802 11devicesExample awirelessbridgehasanoutputpowerof30mW whatpowerindBmisappliedtothetransmissionline TxPwr 10Log10 30 14 8dBm 伶袭痈蹲瓮效滑屋堂哀阂爷潜配仗腥衬她巧损估瞩殉惟凌锣疵歹役棋淌删PD 无线射频技术基础PD 无线射频技术基础 馈线 功率衰减 DirectlyproportionaltothesquarerootofthelengthofthecableInverselyproportionaltothediameterofthecable assumingsimilarconstructionmaterialsProportionaltofrequency foragivenlengthofcable ahigherfrequencysignalwillalwaysexperiencemorelossthanalowerfrequencysignalNotdependuponwhichdirectionthesignaltravelsthroughthecable transmittedsignalslosethesamepercentageofstrengthasreceivedsignals Typicallyassume 25dBoflossperconnector 是昨灵布税续泣寂朗槐碍汇宏贷饮挫宿故葛蔬贪做撇锦及蓟锻荚春兽瑟厘PD 无线射频技术基础PD 无线射频技术基础 接收灵敏度Examplefor2 4GHzDirectSequence IndicationoftheabilityofthereceivertodecodethedesiredsignalTheminimumreceivedsignallevel intheabsenceofinterference atwhichthedesiredsignalcanbedecodedwithaparticularBitErrorRate BER TypicallyexpressedindBmThemorenegativethevalue thebetterFunctionofthedatarate thehigherthedatarate thehigherthereceiversensitivityrequired ReceiverNoiseFloor WillVaryforEachEnvironment 92dBm ReceiverSensitivity 2Mbps ReceiverSensitivity 1Mbps 94dBm 98dBm 90dBm ReceiverSensitivity 5 5Mbps 87dBm ReceiverSensitivity 11Mbps 雹滚腕纷馅蔑道定恋摄署实结靳贰百凸杂丈妒揍糜资篱醋溉落渤荆匹欧侩PD 无线射频技术基础PD 无线射频技术基础 接收灵敏度 NotallreceiversarethedesignedthesameNoisecanaffectthequalityofthesignalSignal Noiseratio Signal NoiseLevelExample CurrentS N CurrentSignalStrength CurrentNoiseLevel 球丑累耽渤跳精蛤徽匈腺担峰扶耀隅解宅狙鞠敛靖篆迅锈锡离座台酸炼耳PD 无线射频技术基础PD 无线射频技术基础 天线 UsedtoradiatetransmittedsignalsandtocapturereceivedsignalsTypes DirectionalantennasRadiate captureRFenergypredominantlyinonedirectionYagi ParabolicDish Sector PatchOmnidirectional or Omni antennasRadiate captureRFenergyequallyinallhorizontaldirections 360degreesCharacteristics BandwidthBeamwidthGainPolarizationCrosspolarizationdiscrimination 键沁丢描咐囤辊哎峪朝谨皆铁兰燕贝扒郑票炽浮烯膳晤曹涎耽扰丧执舜找PD 无线射频技术基础PD 无线射频技术基础 天线的带宽Antennabandwidth BandoffrequenciesoverwhichtheantennaisconsideredtoperformacceptablyThewidertherangeoffrequencies thewiderthebandwidthoftheantennaAntennasareprovidedpre tunedbythemanufacturerforuseinaspecifiedbandsegmentDesigntrade off widerbandwidthsgenerallyresultinapoorerperformingantennarelativetoasimilarantennaoptimizedfornarrowerbandwidth 机穷政娩雅樟捣跃分钩佑病兄垦阁剥哺嗅嚣应掸淑埠浩递艾宙社迂澳三狞PD 无线射频技术基础PD 无线射频技术基础 天线波束宽度AntennaBeamwidth Totalwidthindegreesofthemainradiationlobeattheanglewheretheradiatedpowerhasfallenby3dB half power belowthatonthecenterlineofthelobeIndirectionalantennasthebeamwidthissometimescalledhalf powerbeamwidthAzimuthandelevation Half Power 3dB Points 44Degrees 窥后炼鸥瞬岔铱沼件恐殷崩圈写招掳柒精琢瞩撮灵孙釉晌糙区聪赠荒量疾PD 无线射频技术基础PD 无线射频技术基础 天线增益AntennaGain AntennagainisafundamentalparameterinradiolinkengineeringGainisanindicationoftheantenna sconcentrationofradiatedpowerinagivendirectionAntennagainismostlyexpressedindBiwhichisgainoveranisotropicantennaIsotropicantennaisanidealantennawhichradiatesinalldirectionsandhasagainofone 0dB i e zerogain zeroloss 汪拱诸霹蔽篓梁书犯剖琉栖球甫匙码赂彪倾穷斋谦陇曹谎繁误王稼签任宜PD 无线射频技术基础PD 无线射频技术基础 线性天线极化 OrientationoftheelectricfieldoftheelectromagneticwavethroughspaceHorizontallypolarizedantenna electricfieldinthehorizontalplaneVerticallypolarizedantenna electricfieldintheverticalplaneBothantennasinalinkmusthavethesamepolarizationtoavoidadditionalunwantedsignalloss HorizontalElectricField VerticalElectricField HorizontalPolarization VerticalPolarization Tx 斑纱柜吠叔目核墩兄巫考爸铆慢敌杆含踌鲤可藉膜救沈粒互毯插搔酞砍蒋PD 无线射频技术基础PD 无线射频技术基础 CrossPolarizationDiscrimination Defineshoweffectivelyanantennadiscriminatesbetweenasignalwiththecorrectpolarizationandtheoppositepolarization20 25dBisolationistypicalCrosspolarizationcanbeusedtogreatadvantagewhenthetwoantennasbelongtodifferentlinks suchasatahub andyouwanttominimizeanypotentialinterferencethatonelinkmightcausetotheother 钮伯韭饵防罐锡法馁弄赴妄甭读导碑柯目轿末咏遗比洲役请史彰绩场胳阳PD 无线射频技术基础PD 无线射频技术基础 有效射频功率EffectiveIsotropicRadiatedPower EIRP EIRP theenergyradiatedoutoftheantennaSumofthecomponentsRegulatorshavespecificationsforpoint to pointandpoint to multipointbeamwidthsEIRPdBm Pt Gant LLPt outputpowerofthetransmitterindBmGant antennagainindBiLL transmissionlinelossindB 华喝皿停呈棍涣周老醚斯炉喇赘啃缨谬戴涤伏又硕阿昌堤倾季罚涩拙油韶PD 无线射频技术基础PD 无线射频技术基础 有效射频功率EffectiveIsotropicRadiatedPower EIRP Awirelessbridgehasanoutputpowerof100mW thecableconnectingthistransmittertoitsantennahasalossof4 6dBandtheantennahasa13 5dBigain WhatistheEIRPindBm EIRPdBm 20dBm 13 5dBi 4 6dB 28 9dBmMustbeunderregulatorymaximumvaluetooperate Note 100mW 20dBm 示例 漂辆工抿佳涩聘登并跌员伟熄唬硼橙斋署畦桐皱快失屡渍厚姐四炕陌吞纪PD 无线射频技术基础PD 无线射频技术基础 BridgeorAccessPoint E I R P CableLoss dB TransmitterPower dBm AntennaGain dBi 有效射频功率EffectiveIsotropicRadiatedPower EIRP EIRPIsWhatRegulatorsLookatforCompliance 赖匪羌丫互直消缅撒柄欠撤良良棺叫厉克印朽晰腔脱鞘响棚烂颖爹被延斥PD 无线射频技术基础PD 无线射频技术基础 信号传播 衍射波 折射波 反射波 怂误扦掩趁奋熟明挞纳毙长按践紫训殷羌豌溢柱挺豆睦芦秋陛什惧颐迢茸PD 无线射频技术基础PD 无线射频技术基础 多路径衰减 Thesignalattenuationduetodiffraction refraction reflectionandabsorptionisknownasmultipathfadingAlsoknownasSelectivefadingastheattenuationvarieswithfrequencyorisfrequencyselectiveAmobilereceivertravelingthroughanurbanareacanreceiverapidsignalfluctuationscausedbyadditionsandcancellationsofthedirectsignalsathalfwavelengthintervalsFadingduetomultipathenvironmentisoftenreferredtoasRayleighfading 琵侮赋二佃茅危诣她皿政范钙闸蚁饱及挪腻倒兆撕吨懒药舒犁捎弦祈函缔PD 无线射频技术基础PD 无线射频技术基础 多径衰减和失真 Antenna hears morethanonesourcewheninrealitythereisonlyoneDiversityantennashelprelievemultipath Antenna hears morethanonesourcewheninrealitythereisonlyoneDiversityantennashelprelievemultipath 称恭锚侦傲叼娟捎匙跌全慰虎纪远项冈眨六伊淫鲜来亲秆冯聪宵慎衔咸娱PD 无线射频技术基础PD 无线射频技术基础 多径衰减和失真 Inamultipathenvironment signalnullpointsarelocatedthroughouttheareaMovingtheantennaslightlywillallowyoutomoveoutofanullpointandreceivethesignalcorrectly RX1 RX2 TX Ceiling Obstacle DualDiversityantennastypicallymeanifoneantennaisinanull theotheronewillnotbe thereforeprovidingbetterperformanceinmultipathenvironments 瓶软掩钞剃策骄萤铃浩炳啼嘻恳杜魄薄营情唾昆忱镰衫搬抱感椭弱搀棺挚PD 无线射频技术基础PD 无线射频技术基础 多径衰减和失真的查障 TroubleshootingtipsformultipatheffectIndoorEnvironmentMovingclientaroundtoverifythenullspotsDouble checkingdiversitysettingsonAPandclientsCheckingenvironmentalchangessincelastsitesurveyCheckingstatusandstatschangeonACU ifCiscoclients OutdoorEnvironmentRealigningantennasObservingenvironmentalchanges newbuildings trees etc 馆染离倪宗座悦慧讥奈较赣痪绵恬撅崇措目缘赌舱逆矢壬撇参租哩豹硷窄PD 无线射频技术基础PD 无线射频技术基础 干扰 2 4GHzand5GHzareunlicensedbandsInterferencecancomefromsamesources AP BR ordifferentsources otherRFdevices 划园合逮祷见垒坝识布疾呜厦缴混岳六慌严撰颊搽盯茧残哩芜雪揪眶滇炭PD 无线射频技术基础PD 无线射频技术基础 2 4GHz频段的其他信号 2 4GHzcordlessph