Antenna Theory and Selection

8/12/2019 Antenna Theory and Selection

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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

CONFIDENTIAL

www.huawei.com

RNP Staff Training Dept.

Antenna Theory

and Selection

ISSUE 4.0


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3

RF components are widely used in

wireless system, and affectperformance of network.

Foreword


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References (32pt, No bold)

List all the reference materials

here

Including guideline,

multimedia materials...

20~80pt


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After this course, you will

Master....

Know.... ....

Objectives


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1 Antenna Principle

2 Antenna Classification3 Antenna Performance Index

4 Antenna Selection Principle and Flow

5 New Technology of Antenna

(Applied for TD-SCDMA Mainly)

Contents


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1 Antenna Principle

1.1 Antenna Location and Function

1.2 Antenna Work Principle

1.3 Antenna Work Frequency Band

1.4 Antenna Polarization

Contents


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Antenna Location and Function

Antenna and FeederSystem

Thunder

protector

Feeder(7/8)

Feeder

clip

Feeder

ladder

Grounded

clip

Connector, insulated airproof

tape, PVC insulated tape

Adjustablesupport

Boardantenna

Pole(50~114mm)

Outdoor

jumper

Indoor jumper

Feeder

windowBTS


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Installation of BBU and RRU(DBS3900)

BBU~RRU: Fiber connection

RRU~Antenna: jumper

connection

Fiber

Jumper

Antenna Location and Function

Decrease feeder

loss, enhance

coverage, andsave cost


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1 Antenna Principle





Contents


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Based on the polarization mode:

Alternant circuit in the lead will radiate electromagnetic (EM) waves,

the radiation ability is related to the length and shape of lead.

When the length of lead is close to wave length, circuit in the lead

will increase greatly and radiate strong radio wave, we call this direct

lead as pole.

Antenna Work Principle


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The pole whose two arms are of same length is called dipole. The pole whose two arms are of the same length (1/2

Wavelength) is called as full-wave dipole.

The pole whose two arms are of the same length (1/4

Wavelength) is called as half-wave dipole.

1/2 Wavelength

Wavelength

1/4 Wavelength

1/4 Wavelength

1/2 Wavelength



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Directional Antenna Omni Antenna


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1 Antenna Principle





Contents


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Antenna Work Frequency Band

No matter what is receiving antenna or transmitting antenna, theywork in a certain frequency band. Commonly, when it works in

central frequency, maximum output it has. When frequency

departs from central frequency, the output power will decrease.

According to this feature, antenna work frequency band is defined.

Two definitions:

The frequency bandwidth when antenna gain decreases by 3dB.

The frequency bandwidth considering stated standing wave ratio.

Mobile communication system adopts the second definition.

Antenna work frequency bandwidth is that when the antenna

standing wave ration is not bigger than 1.5.


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1 Antenna Principle





Contents


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The direction of magnetic field is the direction of electromagnetic

wavespolarization.

Vertical Polarization Horizontal Polarization

+ 45 Polarization - 45 Polarization

Antenna Polarization


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Bi-polarizationUni-polarization


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Uni-polarization Antenna

Comparison

Uni-polarization Ant. and Bi-

polarization Ant. Comparison

Vertical Horizontal Uni-polarization Bi-polarization

Horizontal polarized wave parallels

the ground level, the loss is big.

Vertical polarized wave is vertical to

the ground level, the loss is small.

In order to get the diversity gain, there must

be two uni-polarization antennas physically, it

needs more space. Bi-polarization antenna is

composed of two uni-polarization antennas, itcan save the installation space.

Diversity Distance


Electric Field

Magnetic

Field

Dipole

Electromagnetic Wave Propagation Direction


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Polarization Loss

When receiver and arriving electromagnetic wave usedifferent polarization, the receiving signal has polarization

loss. For example, when orbicular polarization antenna

receives signal from uni-polarization antenna, this will cause

3dB loss.

When arriving electromagnetic wave is orthogonal toreceiver, receiver can not get energy from arriving wave.

Arriving wave and receiver are isolated.


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Polarization Isolation

Isolation: the ratio of signal level transmitted by one antenna

to signal level received by another antenna in bi-polar antenna.

1000mW (1W) 1mW

Isolation Calculation:

10log(1000mW/1mW) = 30dB


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1 Antenna Principle





Contents


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2 Antenna Classification

2.1 According to Radiation Direction

2.2 According to Outline

2.3 According to Polarization Mode

Contents


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Classified According to Radiation Direction

Directional

Antenna

Omni

Antenna


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Classified According to Outline

Plate Antenna Cap Antenna

Whip Antenna Paraboloid Antenna


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Vertical Polarization

Omni Antenna

Vertical Polarization

Directional Antenna

Bi-polar

Directional Antenna

Classified According to Polarization Mode


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1 Antenna Principle





Contents


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3 Antenna Performance Index

3.1 Electrical Index

3.2 Mechanical Index

Contents


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Electrical Index


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Antenna Gain

When the input powers are the

same, antenna gain is the ratio of

output power between antenna

and dipole at the same point

along the direction of maximum

radiation, namely the ratio of

square electric field intensity. The

unit is dBd.

Antenna gain is related to

radiation pattern. More narrowthe major lope is, higher antenna

gain it is.


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Difference between dBd and dBi

2.15dB

Isotropic

Dipole

Actual antenna

Antenna gain is 11dBi or 8.85dBd.

11dBi

8.85dBd 2.15dB 2.15dBi ERP

EIRP


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Antenna Pattern

Symmetric Half waveDipole Pattern

Top View Side View

Omni Antenna Pattern Directional Antenna Pattern


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Antenna Pattern

Front-to-back Ratio Beam Width (BW) (called Half-power Angle)

Zero-point Filling

Upper Side Lobe Suppression


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Front-to-back Ratio

Front-to-back ratio is the ratio of front power to back

power. The bigger front-to-back ratio, the better directional

receiving performance.

Back Power Front Power

Front-to-back Ratio (dB) = 10 log , typical value is about 25dB(Front Power)

(Back Power)


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Beam Width

There are more than one lope in radiation pattern of antenna. The

biggest one is called main lope, the other ones are call side lopes.

Along the pattern of main lope, when the power reduces by 3dB

away from the peak point, the angle of these two points is called

half-power beam width. The smaller half-power beam width is, the

better directivity and the stronger anti-interference capability.

Horizontal Pattern

3dB Beam Width

60(eg)

Peak

- 3dB

- 3dB

Peak

- 3dB

- 3dB

15

(eg)

Vertical Pattern


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Beam Width

Antenna is an energy-centralizing device. The enhancement

of transmission in one direction means the reduction of

transmission in other directions. In general, we can enhance

the transmission strength in a certain direction by reducing

the horizontal lobe width so as to increase the antenna gain.

Under a given antenna gain, the horizontal BW is in reverseproportion with the vertical BW:

10 lg 32400aG

Ga: antenna gain, dBi.: vertical BW, degree.

: horizontal BW, degree.


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For example: one omni antenna, gain 11dBi, horizontal BW 360,

vertical BW is:

1.1

324007.15

360 10

o

Beam Width

Because the design and the manufacturing of antenna are limited, actual

vertical BW is small than the value which is calculated above. The smaller

the difference is, the better the antenna is.


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Relationship between Gain and BW

Beam Width


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F

ixedElectricAntennaDowntilt

FE

Antenna Downtilt

Adjust Downtiltby Antenna

Support

Mechanical

D

ownTilt

Mechanical Downtilt

ElectricDow

ntilt

Electric

Downtilt

Actual Downtilt = MechanicalDowntilt + Electric Downtilt

AdjustableElectr

icAntenna

Downtil

t

ME

RE

ME

RCU

RE

Add

RCU


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Antenna Downtilt

Mechanical

Downtilt

ElectricDowntilt

Adjustable Electric Antenna


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9.5 W

80ohms

50 ohms

Forward: 10W

Reflection: 0.5W

VSWR (Voltage Standing Wave Ratio)

If and respectively stand for the input impedance and nominal

impedance of the antenna, the reflectance is

where . The matching

feature of a port can also be indicated by Reflection

Loss . If , will be 13.98

A

oZ

oA

oA

1

1VSWR

50o

Z

1:5.1VSWR dBLR ... .( ) 20 lgR L dB


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Antenna Intermodulation

Passive intermodulation is caused by passive components which work

with high power of multiple channel. And these components are no-

linearity, such as connector, feeder, antenna, filter, etc..

Intermodulation causes:

Magnetism matter

Joint not tightDifferent metallic material connection

Surface of connection is not smooth

Common biggish intermodulation:

Third order intermodulation


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3.1 Electrical Index

3.2 Mechanical Index

Contents


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Other Technical Performances

Port Isolation

Power Capacity

Input Interface of the

Antenna

Passive Inter-modulation

(PIM) Antenna Size and Weight

Wind Load

Working Temperature

and Humidity

Lightning Protection

Three-Proof Capability


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1 Antenna Principle






Contents


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Contents

4.1 Urban 4.2 Suburban

4.3 Rural 4.4 Highway

4.5 Offing 4.6 Mountainous Area

4.7 Tunnel 4.8 Indoor

4.9 Antenna Selection Work Flow


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Antenna Selection - Urban

Environment character:

Dense site layout, required coverage of single site is small. It is

recommended to limit single site coverage, avoid overshooting, reduce

interference and improve the network capacity and quality.

Antenna selection principle:

Frequency band (G/C/U/W)

Antenna polarization:45bi-polar, directional antenna Horizontal beam width: 6065

Antenna gain: 1516dBi (medium gain, when frequency band is high,

1718dBi is recommended.

Downtilt:

FE 6or ME (RE) 0 ~ 10ME 0 ~ 15

Front-to-back ratio25dB

Others: Upper Side Lobe Suppression


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Suburban is a scene between urban and rural. Some areas with many

sites need considering coverage and interference control. Some areas

with few sites are similar to rural, only need considering coverage. The

suburban antenna parameters is between urban and rural.

Antenna selection principle: Frequency band (G/C/U/W)

Bi-polar or vertical polar, directional antenna

Horizontal beam width: 65or 90

No electric downtilt normally. If there is, small electric downtilt antenna isadopted.

Antenna gain: 1518dBi (medium, high gain antenna)

Antenna Selection - Suburban


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Sparse site layout, low traffic, broad coverage. Coverage is the sticking

point. The environment around site should be considered when selecting

antenna.


Directional antenna

Frequency band / Vertical polarization / 90120 horizontal beam width /

High antenna gain, 1618 dBi / No electric downtilt / Zero-point Filling

Omni antenna

Frequency band / Vertical polarization / Antenna gain: 11 dBi / No electric

downtilt / Zero-point Filling

Antenna Selection - Rural


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Low traffic, high speed subscriber, broad coverage. Coverage is the

sticking point. Highway is strip, the site with two sectors installing high

gain antenna or one sector installing 8-shape omnidirectional is adopted.

When one town is near highway, the site of three sectors installing high

gain antenna or one sector installing heart-shape antenna is adopted.


Directional antenna

Frequency band / Vertical polarization / 30horizontal beam width / Antenna

gain, 21dBi / No electric downtilt / Zero-point Filling

8-shape antenna

Frequency band / Vertical polarization / bidirectional, 70horizontal beam

width / Antenna gain, 14dBi / No electric downtilt / Zero-point Filling

Heart-shape antenna

Frequency band / Vertical polarization / 210horizontal beam width /

Antenna gain, 12dBi / No electric downtilt / Zero-point Filling

Antenna Selection - Highway


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Heart-shape antenna

8-shape antenna

Antenna Selection - Highway


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Mountain will block off the propagation of electromagnetic wave. The

path loss is very big. These areas are not easy to be covered.


Directional antenna



Omni antenna

Frequency band / Vertical polarization / Antenna gain, 11dBi / No electric

downtilt / Zero-point Filling

Antenna Selection - Mountainous Area


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Low traffic, broad coverage, no blocks at the scene. The coverage

distance is affected by two factors, propagation loss and earth sphere

curvature. Considering the earth sphere curvature factor, the antenna

height is adopted more than 100 meters.

Antenna selection principle: Directional antenna



Antenna Selection - Offing


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Low traffic, no interference problem.


Tunnel is less than 2km

Yagi antenna, 10~12dBi

Log-periodic antenna

Flat-panel antenna

Tunnel is more than 2km

Leaky cable

Antenna Selection - Tunnel


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Distributed antenna system is adopted to solve the coverage of indoor.


Omni antenna

Frequency band / Vertical polarization / 360horizontal beam width, 90

vertical beam width / Antenna gain, 2dBi

Flat-panel directional antenna


vertical beam width / Antenna gain, 7dBi

Log-periodic antenna


vertical beam width / Antenna gain, 11.5dBi

Antenna Selection - Indoor


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Antenna Selection Work Flow

Files

Preferred AntennaFeeder Cataloguev2.2.xls

Non-preferred AntennaCatalogue v2.2.xls

Approach to acquirelatest version

Notes database:SZXAP06-DS

Filename:appdata\ipd\fl3-

codeapply.nsf The two files are

attached in Welcomepage.

Preferred Antenna

Feeder Catalogue

Antenna Feeder

Scheme

Antenna Feeder Scheme

Major Project?

HQ AuditRegional Office

Audit

Confirm Antenna Type

Confirm

whether it is

preferred

antenna?

Customer

Leading

Antenna QuotationLeading

Succeed?

Head of Regional

Wireless Technical

Sale Dept.

Approval

Head of Antenna

Feeder SPDT Cost

& System Dept.

HQ Approval

Quotation Info. To Antenna

Coordinator of HQ

Antenna Feeder

Scheme and Antenna

Selection Auditing

Customer Leading

Antenna Selection

Approval

Yes

No

Yes

No

Yes

No

YesYes

NoYes

No

No


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1 Antenna Principle






Contents


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Dynamic Multiple Beam Antenna


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Features:

Multiple beam forming

Beam direction control

Beam width control

Beam distance control


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Load balance


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Cellular optimizationeffective coverage adjustment


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Dedicate beam allocation


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Smart Antenna

Difference from multiple beam antenna

Antenna Type Downlink Beam

Quantity for

Every User

Automatic

Adjustment

Beam

Beam Locating

and Combining

Algorithm

Dynamic multiple

beam antenna

Multiple No No

Smart antenna One Yes Yes


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Smart Antenna

Two Algorithm

Handover Multiple Beam Adaptive Beam


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Smart Antenna

Link Level System Level

Restrain interference

Improve SNR

Improve system capacity

Improve coverage

Improve QoS, bit rate, mobility rate

Smart antenna functions:


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Question

Whatsthe function of antenna?

According to the radiation direction, how

many kinds of antennas are there? What

are they?

Does bi-polar antenna represent two

antennas actually?

What are the important electric indexes for

antenna selection?

What is the relation between dBi and dBd?

Which order of intermodulation is biggish

affection to wireless communicationsystem?


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Antenna Theory and Selection