Download - 04) GSM-BTS Antenna System_MOO_24Feb06

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GSMGSMBTS ANTENNABTS ANTENNA


OBJECTIVESOBJECTIVES

• To know GSM Antenna specifications and definitions

• To identify the difference between space and polarization diversity

• To comprehend the structure of the antenna system in a BTS Site


RADIO WAVESRADIO WAVES

• Is a form of electromagnetic radiation typically generated as disturbances sent out by oscillating charges on a transmitting antenna

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ANTENNAANTENNA

An AntennaAntenna is any device used to

collect or radiate Electromagnetic

Waves


ANTENNA for MOBILE COMMUNICATIONSANTENNA for MOBILE COMMUNICATIONS

• Linear antennas are used:– Monopole (Slab)– Dipole Elements

Mobile Phones

Base Tranceiver Station Antenna

• Single Monopole

• Patch Antenna

• Array of dipoles


ANTENNA ELECTRICAL PROPERTIESANTENNA ELECTRICAL PROPERTIES

• Operating Frequency Band• Input impedance• VSWR• Polarization• Gain• Radiation Pattern• Horizontal/Vertical beamwidth • Downtilt• Front/back ratio• Sidelobe suppression and

null filling• Power capability• 3rd order Intermodulation• Insulation


ANTENNA MECHANICAL PROPERTIESANTENNA MECHANICAL PROPERTIES

• Size• Weight• Radome material• Appearance and color• Working temperature• Storage temperature• Windload• Connector types• Package Size• Lightning Protection


ANTENNA BASIC STRUCTUREANTENNA BASIC STRUCTURE

• Antenna are generally composed of stacked of dipole bundling their radiated power to form a desired antenna pattern in vertical plains around the antenna

• Depending on the gain desired that wants to be achieved several of those dipoles can be arranged on top of one another


GENERATION OF RADIO WAVESGENERATION OF RADIO WAVES

DIPOLES

Wavelength

1/2 Wavelength

1/4 Wavelength

1/4 Wavelength

1/2 Wavelength

Dipole

1800MHz ： 166mm

900MHz ： 333mm


HALF WAVE DIPOLEHALF WAVE DIPOLE

1 个 dipoleReceived Power ： 1mW

Multiple dipole matrixReceived Power ： 4 mW

GAIN= 10log(4mW/1mW) = 6dBd


ISOTROPIC ANTENNAISOTROPIC ANTENNA

Gain=10log(8mW/1mW) = 9dBi

“Omnidirectional array”Received power ： 1mW

(Overlook

Antenna

“Sector antenna”Received power ： 8mW


dBdBd d and dBand dBi i GAIN COMPARISONGAIN COMPARISON

Dipole

Ideal radiating dot source(lossless radiator)

0dBd = 2.15dBi

2.15dB


dBdBd d and dBand dBi i GAIN COMPARISONGAIN COMPARISON


ANTENNA ARRAYSANTENNA ARRAYS


GSM ANTENNA FREQUENCY RANGEGSM ANTENNA FREQUENCY RANGE

Type Frequency Range

GSM 900 890 - 960 MHzGSM 1800 1710 - 1880 MHz

890 - 960 MHz1710 - 1880 MHz

GSM Dual Band


GSM ANTENNA FREQUENCY RANGEGSM ANTENNA FREQUENCY RANGE

BANDWIDTH = 960 - 890 = 70MHz

Optimum 1/2 wavelengthfor dipole at 925MHz

at 960MHz

Antenna Dipole

at 890MHz


IMPEDANCEIMPEDANCE

Standard Value: 50

Cable

50 ohms

Antenna 50 ohms


VOLTAGE STANDING WAVE RATIO (VSWR)VOLTAGE STANDING WAVE RATIO (VSWR)

9.5 W80

ohms50 ohms

Forward: 10W

Backward: 0.5W

Return Loss ： 10log(10/0.5) = 13dB

VSWR (Voltage Standing Wave Ratio)


VOLTAGE STANDING WAVE RATIO (VSWR)VOLTAGE STANDING WAVE RATIO (VSWR)

• 1.5

• = (VSWR-1)/(VSWR+1)

• RL RL = -20lg


BEAMWIDTHBEAMWIDTH

120° (eg) Peak

Peak - 10dB

Peak - 10dB

10dB Beamwidth

60° (eg) Peak

Peak - 3dB

Peak - 3dB

3dB Beamwidth


3dBm HORIZONTAL BEAMWIDTH3dBm HORIZONTAL BEAMWIDTH

• Directional Antenna ： 65°/90°/105°/120°• Omni ： 360°

Omni-directional Directional


3dBm VERTICAL BEAMWIDTH3dBm VERTICAL BEAMWIDTH



BEAMWIDTHBEAMWIDTH


ANTENNA STRUCTURE TYPESANTENNA STRUCTURE TYPES



RADIATION PATTERNRADIATION PATTERN

Typical Flat-Panel Antenna

Typical Omni Antenna


TWO TYPES OF DIVERSITYTWO TYPES OF DIVERSITY

1. SPACE DIVERSITY

2. POLARIZATION DIVERSITY


POLARIZATIONPOLARIZATION

Vertical Horizontal

+ 45degree slant - 45degree slant


SPACE DIVERSITYSPACE DIVERSITY


POLARIZATION DIVERSITYPOLARIZATION DIVERSITY

V/H (Vertical/Horizontal) Slant (+/- 45°)


TYPES OF ANTENNATYPES OF ANTENNA

Linear Polarization,verticalX Polarization, 45


ANTENNA DOWN TILTANTENNA DOWN TILT

• Mechanical down tilt

• Fixed electronic down tilt

• Adjustable electronic down tilt


MECHANICAL DOWN TILTMECHANICAL DOWN TILT

• It is achieved by physically tilting the antenna out of the perpendicular by using down tilt kit

• PROS: Cost efficient and flexible

• CON: Has no effect on the side-lobe characteristics of the antenna


ELECTRICAL DOWN TILTELECTRICAL DOWN TILT

• Electrical downtilt can be fixed or switchable

• Fixed is tuned by the manufacturer

• Switchable allows adjustment in a certain lever on the rear of the antenna

Input Signal



Non down tilt Electronic downtilt Mechanical downtilt


ANTENNA TILT DEVELOPMENTANTENNA TILT DEVELOPMENT

Broad bandMultifunctionalHigh Integrity


ANTENNA TILT DEVELOPMENTANTENNA TILT DEVELOPMENT


FRONT-TO-BACK RATIOFRONT-TO-BACK RATIO

Ratio of maximum mainlobe to maximum sidelobe

F/B = 10 log(FP/BP) typically ： 25dB

Back power Front power


UPPER SIDELOBE SUPPRESSION AND UPPER SIDELOBE SUPPRESSION AND NULL FILLNULL FILL


UPPER SIDELOBE SUPPRESSION AND UPPER SIDELOBE SUPPRESSION AND NULL FILLNULL FILL

Gain reduction as a function of (vertical angle)


INTERMODULATION (IM)INTERMODULATION (IM)

• It occurs when two signals of a different frequency mix in a non-linear device

• It can be a problem at any site that has two or more transmitters

•It can be caused by a transmitter of the same system or by a transmitter in another site that is co-sited or has a site in the neighborhood

913 MHz 936 MHz 959 MHz 982 MHz

IMD@243dBmf1, f2, 2f1-f2, 2f2-f1


PERMITTED POWERPERMITTED POWER

• Continuous :25-1500 watts

• peak :n2p


ISOLATIONISOLATION

1000mW ( 1W) 1mW

10log(1000mW/1mW) = 30dB


ANTENNA MECHANICAL PROPERTIES


DIMENSIONSDIMENSIONS

• LWH– Length ： connected with vertical bandwidth and gain– Width ： connected with horizontal bandwidth– Height ： connected with techniques adopted


WEIGHTWEIGHT

• A factor that can affect transmission and deployment


RADOME MATERIALRADOME MATERIAL

• PVC, Fiberglass

• Anti-temperature, water-proof ， anti-aging ， weather resistant


COLORCOLOR

• Good-looking

• Environment-protecting


COLORCOLOR


TEMPERATURE RANGETEMPERATURE RANGE

OPERATING AND STORAGE•Typical range ： -40°C — +70°C


• 7/16”DIN ， N ， SMA

• female

CONNECTOR TYPECONNECTOR TYPE


• Mast diameter 45-90mm

MASTMAST


• Direct Ground

LIGHTNING PROTECTIONLIGHTNING PROTECTION


By frequency band: GSM900, GSM1800, GSM900/1800

By polarization: Vertical, Horizontal, ±45º linear

polarization, circle polarization

By pattern: Omni-directional, directional

By down-tilt: Non, mechanical, electronic

adjustment, remote control

By function: Transmission, receiving, transceiving

ANTENNA TYPESANTENNA TYPES


– 870-960MHz and 1710-1880MHz– Extended band option with 806-

960MHz – Dual slant ±45º polarization– 65º horizontal beamwidth– Band independent Teletilt™ control– 17dBi gain in both bands– Diplexed or Non-Diplexed versions– Mechanical downtilt mounting option

MULTIPLE BAND ANTENNAMULTIPLE BAND ANTENNA


7/8” MAIN FEEDER

FEEDERFEEDER


1/2” （ JUMPER CABLE ）

JUMPER CABLEJUMPER CABLE


7/16”DIN-F （ DIN CONNECTOR ）

7/16”DIN-M （ DIN & N CONNECTOR ）

CONNECTORCONNECTOR


Rf port 2

Grounding

LIGHTNING ARRESTORLIGHTNING ARRESTOR


• Trimming Tool or Hand Tool Kit• Clamp• Earthing Kit• Wall Glands• Hoisting Stocking• Universal Ground Bar

ACCESSORIESACCESSORIES


Antenna

7/16 Din Connector

7/8“ Cable

Grounding

1/2“ Jumper

Cabinet

EMPGrounding clip

Grounding bar

1/2 Clamp

Tower Top Amplifier

7/8“ Cable

Machine house

1/2 Jumper

ANTENNA SYSTEMANTENNA SYSTEM