6. Materi 6 - Antenna Pada Sistem Cellular

PT3163-SISKOMBER-MODUL:06Modul : 06

SISTEM KOMUNIKASI BERGERAK

Antena pada Sistem Cellular

MALANG, 2011

PT3163-SISKOMBER-MODUL:06

PT3163-SISKOMBER-MODUL:06Macam-Macam Jenis Antena yang ada di BTS1) Omnidirectional2) Sectoring 120o3) Sectoring 60oPada kondisi awal biasanya digunakan pola omnidirectional ( tergantung demand ).Kegunaan dari pola Sectoring a.Menambah kapasitasb. Mengurangi interferensi


PT3163-SISKOMBER-MODUL:06Bentuk Konfigurasi Sektor Sel4 sector ( quad sector )


PT3163-SISKOMBER-MODUL:06Bagaimana bentuk antena pada lokasi site ?


RBS / BTS

=Radio Base Station / Base Transceiver Station

=Merupakan perangkat transceiver yang berhubungan dari / ke pelanggan (Interface / repeater antara MS dan MSC) .

=Elemen-elemen RBS :

Transceiver

Control Unit / BSC / Base Station Controller

Antena

Data terminal

PT3163-SISKOMBER-MODUL:06Radio (Tx & Rx) SystemSignal Source: Informasi & Baseband Processing.Tx-er: Modulator, Channel Encoder, Interleaver, etc.PA: Power Amplifier.Feedline: Cable, Connector and Jumper.Pre-Amp: LNA.Rx-er: Demodulator, Channel Decoder, De-Interleaver, etc.RxerPASignalInformationTxerSignalSource(Voice, data, etc)propagationfeedlineTx filterRx filterPre-Amp


PT3163-SISKOMBER-MODUL:06Structure of TransmitterBB Processing: to process analog signal into digital signal & other processingMod: translate from BB freq. To RF freq depend on type of cellular system being used e.g. G-MSK modulator for GSM.Power Amp:- Class A: high linearity- Class B: greater output power more efficient than Class A, but less linear- Class AB: combined adv. of class A & B become widely used in wireless.- Class C: more power efficient widely used in wirelessBBProcessingModPAInfoSignalJumperJumperCableConnectorDepend ontype of Mod used


PT3163-SISKOMBER-MODUL:06Transmitting CombinersAllows multiple transmitters to feed single antenna, providingMinimum power loss from transmitter to antennaMaximum isolation between transmitters Combiner typesTunedlow insertion loss ~1-3 dBtransmitter frequencies must be significantly separatedHybridinsertion loss -3 dB per stageno restriction on transmitterfrequenciesLinear amplifierLinearity and intermodulation are major design and operation issues


PT3163-SISKOMBER-MODUL:06Generic Structure of RxerBlock diagram of Rxer varies depend on type of modulation, encoder, and/ or base band processing.Parameters to be considered are:- frequency range- dynamic range- sensitivity- distortion- noise- tuning speed


PT3163-SISKOMBER-MODUL:06Antenna: to convert electromagnetic energy from atmosfer electric energy and transfer it to feed lineFeed lineReceiver ComponentsFilter & Pre-Amplifier:- Filter: to pass the wanted signal & attenuated the interference designed to work according to the intended bands-Pre-Amplifier is used to increased S/N of received signals.= Connector Jumper to ease maintenance and installation


PT3163-SISKOMBER-MODUL:06Receiver ComponentsMulticoupler:- used for RF distribution- many signals/users can share the same receive antenna:


PT3163-SISKOMBER-MODUL:064 Basic Antenna System.l/2G=2.14 dBiZ= 73 Wa. Dipolel/4G=4 dBiZ= 36 Wb. monopoleGround planec. LoopGround planeconductorFeed pointd. Microstrip/ patchdielectricl/2l/2l


PT3163-SISKOMBER-MODUL:06Base Station Antenna.Use antenna with higher gainCould be omnidirectional or sectoral depending on cell typeCollinear antenna:OmnidirectionalRadiationPatternboresightmain lobeside lobe(elevation)


PT3163-SISKOMBER-MODUL:06Log periodic dipole array (LPDA)Base Station Antenna.DipolesTransmissionline- BW is smaller than LPDA typical gain 12 14 dBReflectorDriven element (dipole)DirectorsYagi antennaDirectional RadiationPatternmain lobemain lobeside lobeback lobe- very wide BW, with constant SWR typical gain 10 dBi


PT3163-SISKOMBER-MODUL:06Antenna Downtilt


PT3163-SISKOMBER-MODUL:06Vertical Depression Angles


PT3163-SISKOMBER-MODUL:06Types Of Downtilt


PT3163-SISKOMBER-MODUL:06Antenna Downtilt: Reduce Interference


PT3163-SISKOMBER-MODUL:06Antenna Downtilt: Avoid Overshoot


PT3163-SISKOMBER-MODUL:06SWR of AntennaSWR = Vmax/Vmin, define the matching level between antenna and feeder lineReflection coefficient:whererepresent a percent of reflected power defined by:AmplitudeVmaxVminl/2


PT3163-SISKOMBER-MODUL:06Performance Criteria of AntennaAntenna pattern, defined at azimuth and elevation orientation either omni or bidirectional antennaMain lobe & side lobe, the lower side lobe the better resistance to interferenceInput impedance, usually complex matching input ipedance and feeder line impedance is very critical to have maximum power transfer from feeder to antennaBeamwidth, usually defined as angular separation where there is 3 dB reduction from bore-sightDirectivity & Gain, is ratio of radiation intensity at wanted direction and coverage radiation intensity over all direction

Bandwidth, define operating range of antenna, limited by SWR. A typical BW is for SWR 1:1.2 at the band edge.Polarization, defined by orientation of


PT3163-SISKOMBER-MODUL:06Performance Criteria of AntennaFront to Back Ratio, is ratio between main lobe & back lobe, very impotant for directional antenna.Spatial diversity:where f is in MHz


PT3163-SISKOMBER-MODUL:06Antenna Installationa) Towerb) Roof Top, Edge of Buildingc) Roof Topd) Wall Mounting


PT3163-SISKOMBER-MODUL:06Antenna Installation ToleranceApply to physical oriented & plumbness of its installationFor omnidirectional antenna, it is unnecessary. But for directi-onal antenna it is very criticalUsually taken +/- 5% from antenna horizontal/azimuth pattern.Table: Horizontal Antenna Tolerance

Azimuth/Horizontal PatternTolerance from Bore Sight110O+/- 5.5o92O+/- 4.5o60O+/- 3.0o40O+/- 2.0o


PT3163-SISKOMBER-MODUL:06Antenna Isolation


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6. Materi 6 - Antenna Pada Sistem Cellular

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