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
The function of antenna
Collect data
information
Outline of antenna
make optimize
project
Network
optimization
Antenna optimization
Optimize cover range
Regulate and
Deal optimize
Average calling mission
verify
project
Improve calling quality
Improve network running quality
The outline and function 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 antenna
Dipole
Outline of antenna
Wavelength
1/4 Wavelength
1/2 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
Antenna
(top view)
Omnidirectional array
Receive power :4mW
Sector antenna
Receive power : 8mW
10log(8mW/1mW) = 9dBd
Index
Outline of antenna
Technical data
Types of antennas and their development trend
Principle of antenna selection
Electrical properties--frequency
GSM
900
DCS
1800
GSM900+DCS1800
CDMA
Technical data
Electrical properties--frequency
Optimum 1/2 wavelength
for dipole at 925MHz
at
890
MHz
Technical data
at
960
MHz
Antenna
Dipole
BANDWIDTH = 960 - 890 = 70MHz
Electrical properties—input impedance
Technical data
50
Antenna
Cable
50 ohms
50 ohms
Electrical properties—
voltage standing wave ratio
Technical data
forward: 10W
9.5 W
50 ohms
backward: 0.5W
Return Loss： 10log(10/0.5) = 13dB
VSWR (Voltage Standing Wave Ratio)
Electrical properties—
voltage standing wave ratio
Technical data
VSWR1.5
=(VSWR-1)/(VSWR+1)
VSWR=(1+ ||)/(1-| |)
RL=-20lg ||
Electrical properties—
polarize mode
Vertical
+ 45degree slant
Technical data
Horizontal
- 45degree slant
Electrical properties—
polarize mode
V/H (Vertical/Horizontal)
Technical data
Slant (+/- 45°)
Electrical properties—
polarize mode

Linear,vertica

dual linear 45 slant
Technical data
Electrical properties—
gain
Technical data
Antenna radiant energy collection degree and the
energy conversion efficiency
G（、）=4 U（、）/PA
G’= GA/ GA0
0dBd=2.15 dBi
unit：dBd
unit：dBi
Electrical properties—
gain
Technical data
dBd and dBi
idea point fountain（zero
waste equality radiation）
2.15dB
dipole
eg:
0dBd = 2.15dBi
Electrical properties—
gain
Technical data
Electrical properties—
wave width
Technical data
3dB Beamwidth
10dB Beamwidth
Peak - 3dB
60° (eg)
Peak
Peak - 3dB
Peak - 10dB
120°
(eg)
Peak
Peak - 10dB
Electrical properties—
wave width
Technical data
Electrical properties—
wave width
Sector
antenna ：30°/65°/90°/105°/120 °
omni-antenna
：360°
Technical data
Electrical properties—
wave width
定向天线：
Technical data
全向天线：
Electrical properties—
wave width
horizontal
Technical data
3dB beam width 3dB width choose graph
Electrical properties—
declination

No declination

Machine declination

Fixed electrical
declination

Measurable electrical
declination

Remote control
declination

Machine electrical
combine use
Technical data
Electrical properties—
declination
Technical data
Electrical properties—
declination
Technical data
Electrical properties—
declination
No declination
Electrical declination
Technical data
Machine declination
Electrical properties—
declination
Technical data
Electrical properties—
Front to Back Ratio

Technical data
The max value of main petal to
the max value of back petal ratio
Back power
F/B = 10 log( front power / back power )
Front power
typically ： 25dB
Electrical properties—
petal restrain & zero point fill
Technical data
Electrical properties—
petal restrain & zero point fill
Up assistant petal (dB)
Down assistant petal
(dB)
Technical data
Electrical properties—
power capability

Continuous :25-1500watts

peak :n2p
Technical data
Electrical properties—
isolate
For
Technical data
multi-port antenna using, the isolation degree
between every port must be bigger then 30dB
10log(1000mW/1mW) = 30dB
1000mW ( 1W)
1mW
Electrical properties—
isolate

Technical data
The same frequency, different frequency,
dual-frequency antenna port>30dB
Mechanism properties parameter

Length  width  high

length：relate with vertical petal, gain

width：relate with horizontal petal

high：relate with the technology
of antenna
Technical data
Mechanism properties parameter —
material
Technical data

PVC, ABS, fiberglass etc.

Prevent from bask, freeze, salt fog, burning
and aging.
Mechanism properties parameter —
appearance color

good look, environment protection
Technical data
Mechanism properties parameter —
working degree

type value：
-40°C—+70°C
Technical data
Mechanism properties parameter —
wind carry

For example:
83N at 160 km/h
Technical data
Mechanism properties parameter —
windward

The smaller
the better
Technical data
Mechanism properties parameter —
tie-in

7/16”DIN，

N，

SMA

female
Technical data
Mechanism properties parameter —
hold pole

Mast diameter 45-90mm
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
kinds of BTS antenna
Types & development
According to
GSM900、GSM1800、
frequency
GSM900/1800 dual-frequency
According to
Vertical，45liner polarize，level，
polarization
circularity polarize
According to
direction chart
Omni-antenna，sector antenna
According to
no，mechanism，fixed electrical，
declination mode
measurable electrical， remote control
According to
function
send，receive，send-receive together
develop trend

Width
frequency
band

Multifunction

High
integrated
Types & development
develop trend
GSM900/1800
Types & development
dual-frequency
and dual-polarize
Remote
control isolate
electrical declination antenna
develop trend
Types & development
+45/900 -45/900
C 900/1800
C 900/1800
+45/900 +45/1800 -45/900 -45/1800
+45/1800 -45/1800
index
Outline of antenna
Technical data
Types of antennas and their development trend
Principle of antenna selection
Radio environment for
principle of antenna selection
suburb/country
antenna choose for
urban
Characteristics
When
principle of antenna selection
of application environment:
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.
Polarize mod
direction chat
As it is hard to choose BTS address and space for antenna, the dualpolarize antenna need to be chose
According duplicate using of frequency, sector antenna need to be
chose
3dB Power
For controlling the cover range to restrain disturb, the horizontal plane
Beam width
3dB power beam width of antenna in urban should be 60~65°
antenna gain
The 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
Down tilt antenna is suggested, and electrical declination antenna in
degree
sometimes.
Radio environment for
principle of antenna selection
urban
antenna choose for
suburb/country
Characteristics

principle of antenna selection
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 90°or 105°horizontal plane 3dB power beam
width is used.
3dB Power
The omni-antenna with 90°or 105°horizontal plane 3dB power beam
Beam width
width or wider is used.
antenna gain
The antenna with high gain is suggested, which is 16-18dBi for sector
antenna or 9－11dBi for omni-antenna in rural and suburb area.
Declination
Mechanism declination is suggested. The zero fill antenna is needed
degree
when the high level of antenna is greater then 50 meters to avoid dark
under antenna phenomenon.
Radio environment for
principle of antenna selection
highway
antenna choose for
highway
Characteristics
Low
principle of antenna selection
of application environment:
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
Choose vertical polarize or dual-polarize antenna according to particular
mod
situation
direction
To cover railway and road, the narrow beam width and high gain
chat
antenna should be used.
3dB Power
The gain of sector antenna is higher, the horizontal plane 3dB power
Beam width
beam width is about 30°
antenna
The gain of sector antenna should be 18dBi－22dBi, and omni-antenna
gain
is 11dBi
Declination
Down tilt is not needed for highway covering, and the mechanism
degree
declination antenna is suggested.
Radio environment for
principle of antenna selection
mountainous area
Figure 6.5 beauty spot
antenna choose for
mountainous area
Characteristics
principle of antenna selection
of application environment:
in
the knap out of the way, serious mountain block, big radio pass loss，
hard to cover area.
Polarize mod
Choose vertical polarize or dual-polarize antenna according to
particular situation
direction chat
3dB Power
Beam width
antenna gain
Choose omni-antenna or sector antenna
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
Choose middle antenna gain according to the distance of cover
area, omni-antenna(9-11dBi), sector antenna(15-18dBi)
If BTS be built on the mountain, when the cover area is under the
Declination degree
mountain, the antenna with zero point filling or declination need
to be chose