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Antenna Basic
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Basic Knowledge of Antenna and Antenna
Selection
Purpose
After learning this course you will be able to:
Know the concept of dipoles
Understand basic properties of antenna
Mater the principle of antenna selection
Index
Outline of antenna
Technical data
Types of antennas and their development trend
Principle of antenna selection
make optimize
project
Network
optimization
Collect data
information
Deal optimize
project
Regulate and
verify
Antenna optimization
Optimize cover range
Average calling mission
Improve calling quality
Improve network running quality
The function of antenna Outline of antenna
Antenna is the conversion for circuit
signal of communication equipment to
radio in the air like the bridge tower.
Antenna is the key equipment for the
sending and receiving of radio.
The gain, covering direction, beam,
available driver power, configuration and
polarization function will affect the
communication.
Outline of antennaThe outline and function of antenna
Wavelength
1/2 Wavelength
1/4 Wavelength
1/4 Wavelength
1/2 Wavelength
Dipole
1800MHz 166mm
900MHz 333mm
Dipole Outline of antenna
One dipole
Receive power
1mw
n dipoles
Receive power
4mw
GAIN= 10log(4mW/1mW) = 6dBd
Dipole Outline of antenna
10log(8mW/1mW) = 9dBd
Sector antenna
Receive power : 8mW
Omnidirectional array
Receive power :4mW
(top view)
Antenna
Dipole Outline of antenna
Index
Outline of antenna
Technical data
Types of antennas and their development trend
Principle of antenna selection
GSM 900
DCS 1800
GSM900+DCS1800
CDMA
Technical dataElectrical properties--frequency
BANDWIDTH = 960 - 890 = 70MHz
Optimum 1/2 wavelength
for dipole at 925MHz
at
960
MHz
Antenna
Dipole
at
890
MHz
Electrical properties--frequency Technical data
50
Cable
50 ohms
Antenna
50 ohms
Electrical propertiesinput impedance Technical data
9.5 W
50 ohms
forward: 10W
backward: 0.5W
Return Loss 10log(10/0.5) = 13dB
VSWR (Voltage Standing Wave Ratio)
Electrical propertiesvoltage standing wave ratio
Technical data
VSWR1.5
=(VSWR-1)/(VSWR+1)
VSWR=(1+ ||)/(1-| |)
RL=-20lg ||
Electrical propertiesvoltage standing wave ratio
Technical data
Vertical Horizontal
+ 45degree slant - 45degree slant
Electrical propertiespolarize mode
Technical data
V/H (Vertical/Horizontal) Slant (+/- 45)
Electrical propertiespolarize mode
Technical data
Linear,vertica
dual linear 45 slant
Electrical propertiespolarize mode
Technical data
Antenna radiant energy collection degree and the
energy conversion efficiency
G=4 U/PA unitdBi
G= GA/ GA0 unitdBd
0dBd=2.15 dBi
Electrical propertiesgain
Technical data
dipole
idea point fountainzero waste equality radiation
eg: 0dBd = 2.15dBi
dBd and dBi
2.15dB
Electrical propertiesgain
Technical data
Electrical propertiesgain
Technical data
120(eg)
Peak
Peak - 10dB
Peak - 10dB
10dB Beamwidth
60 (eg) Peak
Peak - 3dB
Peak - 3dB
3dB Beamwidth
Electrical propertieswave width
Technical data
Electrical propertieswave width
Technical data
Sector antenna 30/65/90/105/120
omni-antenna 360
Electrical propertieswave width
Technical data
Electrical propertieswave width
Technical data
horizontal 3dB beam width 3dB width choose graph
Electrical propertieswave width
Technical data
No declination
Machine declination
Fixed electrical
declination
Measurable electrical
declination
Remote control
declination
Machine electrical
combine use
Electrical propertiesdeclination
Technical data
Electrical propertiesdeclination
Technical data
Electrical propertiesdeclination
Technical data
No declination Electrical declination Machine declination
Electrical propertiesdeclination
Technical data
Electrical propertiesdeclination
Technical data
The max value of main petal to
the max value of back petal ratio
F/B = 10 log( front power / back power ) typically 25dB
Back power Front power
Electrical propertiesFront to Back Ratio
Technical data
Electrical propertiespetal restrain & zero point fill
Technical data
Down assistant petal
(dB)
Up assistant petal (dB)
Electrical propertiespetal restrain & zero point fill
Technical data
Continuous :25-1500watts
peak :n2p
Electrical propertiespower capability
Technical data
1000mW ( 1W) 1mW
10log(1000mW/1mW) = 30dB
For multi-port antenna using, the isolation degree
between every port must be bigger then 30dB
Electrical propertiesisolate
Technical data
The same frequency, different frequency,
dual-frequency antenna port>30dB
Electrical propertiesisolate
Technical data
Length width high
lengthrelate with vertical petal, gain
widthrelate with horizontal petal
highrelate with the technology
of antenna
Mechanism properties parameter Technical data
PVC, ABS, fiberglass etc.
Prevent from bask, freeze, salt fog, burning
and aging.
Mechanism properties parameter material
Technical data
good look, environment protection
Mechanism properties parameter appearance color
Technical data
type value
-40C+70C
Mechanism properties parameter working degree
Technical data
For example:
83N at 160 km/h
Mechanism properties parameter wind carry
Technical data
The smaller
the better
Mechanism properties parameter windward
Technical data
7/16DIN
N
SMA
female
Mechanism properties parameter tie-in
Technical data
Mast diameter 45-90mm
Mechanism properties parameter hold pole
Technical data
Mechanism properties parameter thunder resistant
Technical data
index
Outline of antenna
Technical data
Types of antennas and their development trend
Principle of antenna selection
According to
frequency
GSM900GSM1800
GSM900/1800 dual-frequency
According to
polarization
Vertical45liner polarizelevel
circularity polarize
According to
direction chartOmni-antennasector antenna
According to
declination mode
nomechanismfixed electrical
measurable electrical remote control
According to
function sendreceivesend-receive together
Types & developmentkinds of BTS antenna
develop trend
Width
frequency
band
Multi-
function
High
integrated
Types & development
GSM900/1800 dual-frequency
and dual-polarize
Remote control isolate
electrical declination antenna
develop trend Types & development
C 900/1800 C 900/1800
+45/900 +45/1800 -45/900 -45/1800
+45/900 -45/900
+45/1800 -45/1800
develop trend Types & development
index
Outline of antenna
Technical data
Types of antennas and their development trend
Principle of antenna selection
principle of antenna selectionRadio environment for
suburb/country
Polarize modAs it is hard to choose BTS address and space for antenna, the dual-
polarize antenna need to be chose
direction chatAccording duplicate using of frequency, sector antenna need to be
chose
3dB Power
Beam width
For controlling the cover range to restrain disturb, the horizontal plane
3dB power beam width of antenna in urban should be 60~65
antenna gainThe gain of antenna, which should be used in urban, is 15-16dBi. The
antenna with lower gain could be used to cover the blind urban area.
Declination
degree
Down tilt antenna is suggested, and electrical declination antenna in
sometimes.
Characteristics of application environment:
When The distribution of BTS is dense, the cover range of single BTS need to be small,
the over cover phenomena and the disturb between BTS need to be decreased, the
duplicate using of frequency need to be increased.
antenna choose for
urbanprinciple of antenna selection
Radio environment for
urbanprinciple of antenna selection
Characteristics of application environment:
Environment around should be considered in Sparse distributing, low traffic, larger
coverage situation.
Polarize mod Choose vertical polarize or dual-polarize antenna
direction chat The sector antenna with 90or 105horizontal plane 3dB power beam
width is used.
3dB Power
Beam width
The omni-antenna with 90or 105horizontal plane 3dB power beam
width or wider is used.
antenna gain The antenna with high gain is suggested, which is 16-18dBi for sector
antenna or 911dBi for omni-antenna in rural and suburb area.
Declination
degree
Mechanism declination is suggested. The zero fill antenna is needed
when the high level of antenna is greater then 50 meters to avoid dark
under antenna phenomenon.
antenna choose for
suburb/countryprinciple of antenna selection
Radio environment for
highwayprinciple of antenna selection
Characteristics of application environment:
Low traffic, high speed moving
The covering problem is the key issue. For strap covering, dual-cell coverage is needed.
Sometimes, the omni-cell is used in some spots.
Polarize
mod
Choose vertical polarize or dual-polarize antenna according to particular
situation
direction
chat
To cover railway and road, the narrow beam width and high gain
antenna should be used.
3dB Power
Beam width
The gain of sector antenna is higher, the horizontal plane 3dB power
beam width is about 30
antenna
gain
The gain of sector antenna should be 18dBi22dBi, and omni-antenna
is 11dBi
Declination
degree
Down tilt is not needed for highway covering, and the mechanism
declination antenna is suggested.
antenna choose for
highwayprinciple of antenna selection
Figure 6.5 beauty spot
Radio environment for
mountainous areaprinciple of antenna selection
Characteristics of application environment:
in the knap out of the way, serious mountain block, big radio pass losshard to cover area.
Polarize modChoose vertical polarize or dual-polarize antenna according to
particular situation
direction chat Choose omni-antenna or sector antenna
3dB Power
Beam width
For BTS built on the mountain, if the level of cover area is low, the
antenna with bigger 3dB power beam width need to be chose
antenna gainChoose middle antenna gain according to the distance of cover
area, omni-antenna(9-11dBi), sector antenna(15-18dBi)
Declination degree
If BTS be built on the mountain, when the cover area is under the
mountain, the antenna with zero point filling or declination need
to be chose
antenna choose for
mountainous areaprinciple of antenna selection