03 Antenna Principle and Selection_Huawei

8/21/2019 03 Antenna Principle and Selection_Huawei

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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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Antenna Principle and

Selection


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HUAWEI TECHNOLOGIES CO., LTD. Page 1All rights reserved

Chapter 1Chapter 1 AntennaAntenna

Chapter 2Chapter 2 FeederFeeder


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RF Device of BTSAntenna

TTA

Antennastand

Jumper between

antenna and TTA

Jumper betweenTTA and feeder

Feeder

Lighteningarrester

Jumper betweenlightening arresterand cabinet

BTS312

cabinet

SWITCH BOX

FAN BOX

AIR BOX

P

S

U

P

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U

P

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U

P

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TDU

FAN BOX

AIR BOX

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What is Antenna?

Radiate and receive radio wave ,convert high frequency current

to electromagnetic wave when transmitting, and convertelectromagnetic wave to high frequency current when receiving

Blah

blah

blahbl ah


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Function

Convert high frequency current to electromagnetic wave when

transmitting Convert electromagnetic wave to high frequency current when

receiving

Antenna can not amplify the transmission power, just concentrate

RF power to one direction

Horizontal section Vertical section


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Classification

Classify by working band: UHF, VHF, microwave, etc.

Classify by radiate pattern: omni, directional

Classify by outline: line, pane, parabola feed

Classify by polarization: vertical and horizontal


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omni directiondirectional Antenna

Radiate Pattern


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Outline


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vertical polarizationOmni antenna

dual polarizationdirectional antenna

Polarization

vertical polarization

directional antenna


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Radiate Pattern

Omni antenna

lobe

Direction

antenna lobe


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Radiate pattern


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Dipole and Isotropic

Dipole

1/4 wave length

1/4 wave length

1/2wave length

Isotropic

Ideal radiator with same ability on all direction!


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Gain

The radiation ability of certain antenna overtop dipole or isotropic

Indicates the antenna feature of electromagnetic radiation in specificdirections

Unit: dBi/dBd

theory source

l/2 antenna

Direction antenna

dBd

dBi

dBi =dBd+2.15

dB/dBm?


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Forward to Back Ratio

The ratio of main lobe signal strength to back lobe

This value is within 1845dB. In urban, it is suggested to usethe antenna with high F/B ratio


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Beam Angle

HPBW: Half Power Beam Width

Lobe angle between two points, the power of which reduce to

the half of that of the maximum radiate direction

Vertical HPBW and Horizontal HPBW

60 (eg) Peak

- 3dB

- 3dB

15 (eg) Peak

Peak - 3dB

Peak - 3dB

Horizontal sectionVertical section


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Downtilt

To control coverage

To decrease inter modulation

Realization: electron and mechanism


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mechanism

electron

Downtilt


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Effect of Electrical Downtilt

No Down tilt Electron Down tilt


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Effect of Mechanism Downtilt

No Down tilt Mechanism Down tilt


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Effect of different methods

10(E) 10(M)6(E)+ 4(M)


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Polarization

The direction of electro - vector radiated by antenna. The

vertical polarization wave is vertical with the plane of ground,

and the horizontal polarization waves parallel with the plane of

ground

Single antenna has only one polarization direction.

Dual polarized antenna contains two single - polarized antennain one entity. Dual polarization antenna usually adopts +45/ -45

degree orthogonal polarization.


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Polarization

VERTICAL HORIAONTAL

+ 45 - 45


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Dual Polarization

V/H +/- 45


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Main to lower side

Main to upper side

Upper Side Lobe Suppression


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Distributed Antenna System

BTSBTS

Power

splitter

Power

splitter

Power

splitter

coupling

coupling

coupling

coupling

Small

antenna

Small

antenna

Small

antenna

Small

antenna

Small

antenna

Small

antenna

Small

antenna

coupling

Dual direction

amplifier

Dual direction amplifier


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Optical Fiber Distributed Antenna

The optical fiber repeater is mainly adopted in the case

of wide coverage and long distance transmission

signal

Optical transceiver Opticaltransceiver

Optical transceiver

Optical

transcei

ver

transceiver

transceiver


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Leaky Feeder

Coaxial cable with perforated leads

It is mainly adopted for tunnel, metro and with high cost of

equipment and installing

Tx/Rx

Matching load

Matching load



Power splitter


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Leaky Feeder

Coaxial cable with perforated leads

Produce constant field-strength along cable runs

Work at wide-band

Radiating loss become higher with high frequency

Very large bending radius

Formerly often used for tunnel coverage

Expensive


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Feature of Leaky Cable

Transmission loss per hundred meter

Typical value : 10~40 dB per 100m

Couple Loss at 1 meter distance

Typical value 55 dB (at 1m)


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Comparison with Distributed Antenna

High cost

Not flexible

Need power supply

High cost

High loss

Disadvantage

Far area coverage

Metro, Tunnel

High building,Business center

Applicability

Low loss

Easy installation

Optical

FlexibleLeaky feeder

Flexible

Low cost

Reliable

Coaxial Feed

AdvantageDistributed System Type


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Selecting Antenna Selecting Antenna

Selecting Antenna

The selection for antenna is an important part of

determining the network quality.

According to the requirements of coverage and service

quality, traffic distribution, landform, coverage in theentire network, and interference, to select the antenna.

According to landform or traffic distribution, the

environment of using antenna can be categorized into:

City, suburb, countryside, highway, mountainous area,

offing, tunnel, and indoor environment


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Principles of Selecting Antenna

Selecting Antenna for the BTS in the city

Choose the directional antenna with 6065 half power angle.

Choose the antenna with about 15dBi gain.

Choose the antenna with 36tilt angle.

Choose dual polarization antenna.


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Principles of Selecting Antenna Selecting antenna for the BTS in the suburb

According to actual conditions, choose the directional

antenna with 65or 90 half power angle.

Choose 1518dBi middling or high gain antenna.

According to actual conditions, determine whether the tilt

angle should be used.

Dual polarization antenna and vertical polarization antenna

are both available.


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Principles of Selecting Antenna Selecting antenna for the BTS in the countryside

According to actual conditions, choose 90or 120

directional antenna or omni-directional antenna.

Choose directional antenna with 1618dBi gain.

Do not choose presetting tilt antenna. Choose null filling

antenna for the high BTS.

The vertical polarization antenna is recommended.


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Principles of Selecting Antenna

Selecting antenna for the BTS on the

highway

In general, choose narrow-beam and

high-gain directional antenna. Accordingto actual conditions, you also can choose

8-shaped antenna or omni-directional

antenna.

Because the BTS on the highway mustcover a long distance, do not choose the

presetting tilt antenna.

The vertical polarization antenna is

recommended.

The front-to-back ratio of the directional

antenna should not too great.


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Principles of Selecting AntennaPrinciples of Selecting Antenna

Selecting antenna for the BTS in the

tunnel

Tunnel shorter than 2 km

Install the 10dB-12dB Yagi antenna/log-

periodic antenna/flat antenna in the jaws of

tunnel to cover a road that is less than 2km.

Tunnel longer than 2 km

Use leaky feeder, coaxial cable, and fiber

distribution system.


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Principles of Selecting AntennaPrinciples of Selecting Antenna

Selecting Indoor Antenna

Omni-directional antenna

Vertical polarization, 2dBi gain, cap-shaped or cup-shaped,

small size, convenient for installation, graceful

Directional antenna

Vertical polarization, 90half power angle

7dBi gain

A t H i ht


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Antenna Height

Due to the installation space or cell planning, the heights of

antennas that are in different cells of a BTS can be different.

For the BTS in the city, the height of antenna is about 25m. For the BTS in the suburb, the height of antenna is about 40m.

If an antenna, particularly the omni-directional antenna, is too

high, the coverage level of the place that nears to the antenna

may be lowered, that is, no signal under the power.

In addition, the too high antenna may lead to cross coverage

and intra-frequency/neighboring-frequency interferences that

affect the network quality.

Principles of Design for Antenna Height Principles of Design for Antenna Height

Azimuth Angle


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Principles of Design for Antenna Azimuth Angle Principles of Design for Antenna Azimuth Angle

Azimuth Angle

Based on signal coverage, ensure that the azimuth angles of three sectors are the

same. Adjust the azimuth angles of antennas according to important coverage

objects on the border of city and suburb, in the traffic artery and isolated site of

suburb.

To enhance the signal strength and improve call quality, adjust the major lobe of

antenna to face to the heavy-traffic areas.

To control interference, adjust the major lobe of antenna to be apart from intra-

frequency cells.

The cross coverage areas of neighboring cells in the city should not exceed 10%.

The cross coverage areas of neighboring cells in the suburb and village should be

not too large. The azimuth angle of neighboring cells should not less than 90.

To avoid cross coverage, do not make the major lobe of antenna face to the

straight streets in the crowded areas.


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Principles of Design for Tilt Angle Principles of Design for Tilt Angle

Tilt Angle

The beam tilt is a basic technology for improving Frequency Reuse

capability.

The antenna tilt technology is used to control coverage scope and

reduce the interferences in the system.

To reduce the interferences from co-channel cells and meet the

coverage requirements, set the tilt angles based on specific

conditions.

The design for tilt angle should be based on transmitter power,

antenna height, cell coverage, and radio environment.


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Tilt Angle

The antenna tilt is categorized into electrical mode and mechanicalmode. The angle of the electrical tilt is relative to the model of antenna.

The angle of the mechanical tilt is adjustable, but it is limited by

installation accessory and signal transportation. Often the angle should

not exceed 15.

The electrical tilt and mechanical tilt have surface radiations that differ

with the increases of angles.


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Chapter 1 AntennaChapter 1 Antenna

Chapter 2 FeederChapter 2 Feeder


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Feeder Feeder selection

Type : 1/27/85/4

Select 5/4 in the case of feeder length is more than 80 m

and otherwise select 7/8 in 900MHz

Select 5/4 in the case of feeder length is more than 50 m

and otherwise select 7/8 in 1800MHz

Feeder curvature should not be so big, outer conductor

should be connected to earth

LG0.251.156.74.47HFC22D - A(7/8 )

6090.31.156.465.874.03SYFY - 50 - 22(7/8 )

ACOME0.221.156.64.3M1474A(7/8 )

ANDREW0.381.154.774.313.172.98LDF6 -50(5/4 )

ANDREW0.251.156.465.874.34.03LDF5 -50A(7/8 )

2,0001,7001,000890manufacturer

BendRadius (m)VSWR

LOSS dB/100m (MHz)TYPE


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03 Antenna Principle and Selection_Huawei