Basic Knowledge of Antenna

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


10log(8mW/1mW) = 9dBd

Sector antenna

Receive power : 8mW

Omnidirectional array

Receive power :4mW

(top view)

Antenna


Index

Outline of antenna

Technical data



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)


Technical data

Linear,vertica

dual linear 45 slant


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


Technical data


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


Technical data

Sector antenna 30/65/90/105/120

omni-antenna 360


Technical data


Technical data

horizontal 3dB beam width 3dB width choose graph


Technical data

No declination

Machine declination

Fixed electrical

declination

Measurable electrical

declination

Remote control

declination

Machine electrical

combine use

Electrical propertiesdeclination

Technical data


Technical data

No declination Electrical declination Machine declination


Technical data


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



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



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


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


highwayprinciple of antenna selection


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


mountainous areaprinciple of antenna selection


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

Documents

Basic Knowledge of Antenna