6.antenna introduction(v0.1)
TRANSCRIPT
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CDMAAntenna Introduction
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Syllabus BTS Antenna System
Introduction
Antenna Diversity
Electrical properties
Mechanical properties
Antenna Development
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BTS Antenna System Introduction
antenna
7/16 Tie-in
1/2“
cable
7/8“ cable1/2 cable
BTS
arrester
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Syllabus BTS Antenna System
Introduction
Antenna Diversity
Electrical properties
Mechanical properties
Antenna Development
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Antenna Diversity
Space Diversity
Space Diversity:when there exist certain space between two
receiving antennas,they can receive the same signal with
different fading envelope . and if the correlation coefficient is
less than 0.7, the diversity receiving requirement is met.
Space Diversity requires : D>10λ h/D≤11
Where H : the height of the antenna.D : the distance between two antennas
Space Diversity is only used in horizontal
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Polarization Diversity
Polarization Diversity can beobtained if dual polarization (+
45°/- 45°) antenna is used at each
sector of each carrier
Antenna Diversity
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Syllabus BTS Antenna System
Introduction
Antenna Diversity
Electrical properties
Mechanical properties
Antenna Development
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Electrical properties
Blah blahblah bl ah
Frequency Range
Impedance
Dipoles Polarization
Gain
VSWR Beamwidth
Downtilt
PatternElevation Upper Side lobes & Null Fill
Third Order Intermodulation
Front to Back Ratio Isolation
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Wavelength
1/2 Wavelength
1/4 Wavelength
1/4 Wavelength
1/2 Wavelength
Dipole
1800MHz :166mm
900MHz :333mm
Dipoles
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One dipole Received Power :1mW multiple dipoles Received Power :4 mW
GAIN= 10log(4mW/1mW) = 6dBd
Dipoles
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10log(8mW/1mW) = 9dBd
Sector antenna
Received Power :8mW
Omnidirectional array
Received Power :4mW
(down look)
Antenna
Dipoles
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Frequency Range
For CDMA1900 system, the frequency
range of antenna can be 1850-1990MHZ
For CDMA800 system,the frequency range
of antenna can be 824-896MHZ
For GSM900 system,the Frequency
Range of antenna can be 890-960MHz、
870-960MHz、807-960 MHz or 890-1880MHz.
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BANDWIDTH = 896 - 824 = 72MHz
Optimum 1/2 wavelength
for dipole at 860MHz
at896
MHz
Antenna
Dipole
at824
MHz
The Frequency Range of antenna in
CDMA800M system
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Impedance
50
Cable
50 ohms
Antenna
50 ohms
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9.5 W80
ohms50 ohms
forward: 10W
reverse: 0.5W
Return Loss:10log(10/0.5) = 13dB
VSWR (Voltage Standing Wave Ratio)
VSWR
576.12236.01
2236.01
1
1VSWR
10
5.0
==
Usual Request:VSWR 1.5
Reflection Coefficient:=(VSWR-1)/(VSWR+1)
Return Loss:RL=-20lg
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Polarization
Vertical Horizontal
+ 45degree slant - 45degree slant
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V/H (Vertical/Horizontal) Slant (+/- 45°)
Polarization
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Linear,vertical
Polarization
dual linear 45 slant
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Gain
Ratio of antenna power density at a
distant point relative to that of an
isotropic radiator as the two input powervalues are the same.
Unless otherwise specified, the gainusually refers to the direction of
maximum radiation.
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Antenna gain is usually expressed in dBi or dBd
dBi
Gain relative to an isotropic antenna when the
reference antenna is an isotropic antenna.
dBd
Gain relative to a half-wave dipole when the
reference antenna is a half-wave dipole.
Gain
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half-wave dipole
isotropic radiator
eg: 0dBd = 2.15dBi
2.15dB
Gain
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Pattern
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120° (eg) Peak
Peak - 10dB
Peak - 10dB
10dB Beamwidth
60° (eg) Peak
Peak - 3dB
Peak - 3dB
3dB Beamwidth
Beamwidth
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3dB Beam width Horizontal
Directional Antenna:65°/90°/105°/120°
Omni Antenna:360°
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3dB Beam width VerticalDirectional Antenna Omni Antenna
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Down Tilt
Mechanical Downtilt
Settled Electrical Downtilt
Modified Electrical Downtilt
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Down Tilt
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Down Tilt
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No Downtilt Electrical DowntiltMechanical
Downtilt
Down Tilt
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Down Tilt
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Front to Back Ratio
The ratio of front max beam to
back max beam
F/B = 10 log typically: 25dB(Front Power)
(Back Power)
Back Power Front Power
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Elevation Upper Side lobes & Null Fill
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Elevation Upper Side
lobes(dB)
Sidelobes
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Null Fill
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Permitted Power
The permitted power range
of common antenna
25-1500 W
The permitted power of
BTS antenna should bebigger than 200 W
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Third Order Inter modulation
IMD@243dBmf 1, f 2, 2f 1-f 2, 2f 2-f 1
830MHz,835MHz,840MHz,845MHz
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1000mW ( 1W) 1mW
10log(1000mW/1mW) = 30dB
Isolation
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Syllabus BTS Antenna System
Introduction
Antenna Diversity
Electrical properties
Mechanical properties
Antenna Development
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Mechanical properties
Weight
Radome Material
Operation and Storage
Configuration Parameters
Mast
Light Protection
Dimensions
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Dimensions
lengthwidthheight
length :be related to vertical
beamwidth and gainwidth : be related to horizontal
beamwidth
height : be related to thetechnology of antenna
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Weight
Having an Influence on
Transportation and Construction
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Radome Material
PVC, ABS, fiberglass,etc
Sun-proof 、prevent frostbite,Fire-
retardant etc
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Operation and Storage
Storage Temperature Range:
Operating Temperature Range:
Typical:-40°C — +70°C
Typical:
-40°
C —
+70°
C
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Configuration Parameters
Flat Plate Area
Shipping Dimensions
Wind Load
lengthwidthheight
Eg: 83N at 160 km/h
The smaller the better
Connector Type
7/16”DIN,N,
SMA female
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Mast
Mast diameter 45-90mm
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Light Protection
DC Ground
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Syllabus
BTS Antenna System
Introduction
Antenna Diversity
Electrical properties
Mechanical properties
Antenna Development
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Antenna Development
Wide Frequency
Much Function
High Integration
Smart Antenna
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