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Transcript of GSM Antenna System
8/15/2019 GSM Antenna System
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Antenna System
ZTE University
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Objective
By the end of this course, you will be able:
To Understand the concept of dipole
To state GSM antenna specifications
To comprehend the principle of antenna selection
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Content
Antenna overview
Antenna specifications
Principle of antenna selection
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Blah blah
blah bl ah
Radio Waves
A form of electromagnetic radiation typically
generated as disturbances sent out by
oscillating charges on a transmitting antenna
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Definition
An Antenna is any
device used tocollect or radiate
Electromagnetic
Waves
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Linear antennas are
used:
Monopole (Slab)
Dipole Elements
Mobile Phones
Base Tranceiver
Station Antenna
• Single Monopole
• Patch Antenna
• Array of dipoles
Antenna for mobile communication
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Antenna basic structure
Antenna are generally
composed of stacked of dipole
bundling their radiated powerto form a desired antenna
pattern in vertical plains
around the antenna
Depending on the gain desired
that wants to be achievedseveral of those diploes can
be arranged on top of one
another
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DIPOLES
Wavelength
1/2 Wavelength
1/4 Wavelength
1/4 Wavelength
1/2 Wavelength
Dipole
1800MHz :166mm
900MHz :333mm
Generation of radio waves
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1个 dipoleReceived Power :1mW
Multiple dipole matrixReceived Power :4 mW
GAIN= 10log(4mW/1mW) = 6dBd
Half wave dipole
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Gain=10log(8mW/1mW) = 9dBi
“ Omnidirectional array”
Received power :1mW
(Overlook
Antenna
“Sector antenna”
Received power :8mW
Isotropic antenna
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Dipole
Ideal radiating dot source
(lossless radiator)
0dBd = 2.15dBi
2.15dB
dBd and dBi
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dBd and dBi
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Content
Antenna overview
Antenna specifications
Principle of antenna selection
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Antenna 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
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Type Frequency Range
GSM 900 890 - 960 MHz
GSM 1800 1710 - 1880 MHz
890 - 960 MHz
1710 - 1880 MHzGSM Dual Band
GSM antenna frequency range
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BANDWIDTH = 960 - 890 = 70MHz
Optimum 1/2 wavelength
for dipole at 925MHz
at
960
MHz
AntennaDipole
at
890
MHz
GSM antenna frequency range
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Standard Value: 50Ω
Cable
50 ohms
Antenna
50 ohms
Impedance
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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)
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VSWR 1.5 Γ = (VSWR-1)/(VSWR+1)
RetureLossRetureLoss = -20lg Γ
Calculation of VSWR
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120
(eg) Peak
Peak - 10dB
Peak - 10dB
10dB Beamwidth
60
(eg) Peak
Peak - 3dB
Peak - 3dB
3dB Beamwidth
Bandwidth
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Directional Antenna
65
/90
/105
/120
Omni 360
Omni-directional Directional
3dBm horizontal beamwidth
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Omni-directional Directional
3dBm vertical beamwidth
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Omni-directional Directional
Antenna structure types
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Vertical Horizontal
+ 45degree slant - 45degree slant
Polarization
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Space diversity
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V/H (Vertical/Horizontal) Slant (+/- 45 )
Polarization diversity
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Linear Polarization,vertical
X Polarization, ±45 °
Types of antenna
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Antenna down tilt
Mechanical down tilt
Fixed electronic down tilt Adjustable electronic down tilt
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Mechanical down tile
It is achieved by physically
tilting the antenna out of theperpendicular by using down
tilt kit
PROS: Cost efficient and
flexible
CON: Has no effect on theside-lobe characteristics of the
antenna
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Input Signal
Electrical down tilt
Electrical downtilt can be fixed or adjustable
Fixed is tuned by the manufacturer
Adjustable allows adjustment in a certain level on the rear of the
antenna
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Non down tilt Electronic downtilt Mechanical
downtilt
Down tilt
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Antenna tilt development
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F/B = 10 log(FP/BP) typically : 25dB
Back power Front power
FRONT-TO-BACK Ratio
Ratio of maximum mainlobe to maximum
sidelobe
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Upper sidelobe suppression and null fill
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Upper sidelobe suppression and null fill
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913 MHz 936 MHz 959 MHz 982 MHz
IMD@2×
43dBmf1, f2, 2f1-f2, 2f2-f1
Intermodulation
It occurs when two signals of a different frequency mix in anon-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
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1000mW ( 1W) 1mW
10log(1000mW/1mW) = 30dB
Isolation
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Antenna mechanical properties
Size
Weight
Radome material Appearance and color
Working temperature
Storage temperature
Windload
Connector types Package Size
Lightning Protection
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Dimension
L×W×H
Length:connected with vertical bandwidth and gain
Width:connected with horizontal bandwidth Height:connected with techniques adopted
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Weight
A factor that can affect transport and
deployment
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PVC, Fiberglass
Anti-temperature, water-proof , anti-
aging,weather resistant
Radome materials
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Good-looking
Environment-protecting
Color
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Temperature range
Operation and storage
Typical range:-40°C — +70°C
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Connector type
7/16”DIN,N,SMA
Female/male
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Mast diameter 45-90mm
Mast
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Direct Ground
Lightning protection
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Antenna types
By frequency band: GSM900, GSM1800,
GSM900/1800
By polarization: Vertical, Horizontal,±45º linearpolarization, circle polarization
By pattern: Omni-directional, directional
By down-tilt: Non, mechanical, electronic
adjustment, remote control
By function: Transmission, receiver,transceiver
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7/8” Main feeder
Feeder cable
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1/2” JUMPER CABLE)
Jumper cable
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7/16” DIN-F DIN CONNECTOR)
7/16” DIN-M DIN & N CONNECTOR)
Connector
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Rf port 2
Grounding
Lightning arrestor
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Accessories
Trimming Tool or Hand Tool Kit
Clamp
Earthing Kit
Wall Glands
Hoisting Stocking Universal Ground Bar
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Antenna
7/16 Din
Connector
7/8“ Cable
Grounding
1/2“ Jumper
Cabinet
EMP
Grounding clip
Grounding bar
1/2 Clamp
Tower Top
Amplifier
7/8“ Cable
Machine house
1/2 Jumper
Antenna system
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Content
Antenna overview
Antenna specifications
Principle of antenna selection
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Radio propagation in cities
Environment features: Densely deployed BTS,small coverage area
Decrease over coverage and interference, increase
frequency reuse factor
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Radio propagation in suburb/rural area
Environment features:
Loosely deployed BTS
light traffic large coverage
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Antenna selection in suburb/rural area
Polarization Both dual-polarized and vertical
Direction directional
3dB bandwidth 90°105°
Gain16-18dBi directional
or 9-11dBi omni
Tilt down angle Mechanical tilt down; 50m high; null fill
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Radio propagation in road/highway environment
Environment features:
Low traffic
Fast movingsubscribers
Focus on coverage.
Strip coverage
Two sectors
Omni-cell when pass
towns or tourist site
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Antenna selection for highway
Polarization Both dual-polarized and vertical
Direction Narrow beamwidth directional
3dBbandwidth
30°
Gain 18dBi-22dBi
Tilt down
angleNo tilt down
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Radio propagation in mountainous environment
Environment features:
Block by mountains
Big propagation loss Difficult to cover
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Antenna selection in mountainous area
Polarization Both dual-polarized and vertical
Direction Omni or directional
3dB bandwidth Big 3db verticle bandwidth
GainOmni (9-11dBi)
Directional (15-18dBi)
Tilt down angle Null fill & electrical tilt down
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