OMP110030 Antenna Basics ISSUE1.02

7/29/2019 OMP110030 Antenna Basics ISSUE1.02

1/61

www.huawei.com

Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved.

Antenna Basics


2/61

Copyright 2011 Huawei Technologies Co., Ltd. All rights reserved. Page2

Foreword

Antenna is the most basic and important equipment in

radio network. The specification and selection of

antenna is very important for network QoS.


3/61


Contents

1. Antenna Fundamentals

2. Antenna Working Principle

3. Antenna Specifications

4. Antenna Selection

5. Electric Downtilt Antenna


4/61


Contents







5/61


Contents


1.1 Overview

1.2 Antenna type

1.3 Polarization


6/61


Overview

Lightning

Arrester

Main Feeder7/8

Feeder

Clip

Feeder

Support

Grounding

Point

Antenna Adjustable Support

GSM/CDMA

Panel Antenna

Holding Pole ( 50~114)

BTS

Wall


7/61


Contents


1.1 Overview

1.2Antenna type

1.3 Polarization


8/61


Antenna Type

Division

standardType

Radiation direction Omni-directional antenna

Directional antenna

Structural feature

Linear antenna

Panel antenna

Cap antenna

Polarization way

Vertical polarization antenna

(unipolarization antenna)

Cross polarization antenna

(dual polarization antenna)


9/61


Antenna Type By Direction

Directional antenna omni antenna


10/61


Antenna Type By Structure

Plate-shape antenna Cap-shape antenna

Whip-shape Paraboloid antenna


11/61


Antenna Type By Polarization

Omni antennaUni-polarization

Directional antenna

Dual polarization

Directional antenna


12/61


Contents


1.1 Overview

1.2 Antenna type

1.3 Polarization


13/61


Polarization (Cont.)

In electromagnetic wave radiated by antenna, the directionof electric field vector is the direction of antenna

polarization.

Horizontal PolarizationVertical Polarization

+45o Polarization -45o Polarization


14/61


Polarization

Two antenna combined together, transmit and receivetwo independent wave.

+ 45/ - 45Polarization0/ 90Polarization


15/61


Polarization Loss

When polarization direction of transmited wave andreceiving antenna is different, there will be a Polarization

Lossduring receival.

Linear Polarizationwave will take 3dB loss when received

by Circular Polarizationantenna.

Horizontal Polarizationantenna can not receive the

energy from Vertical Polarizationwave.


16/61


Contents







17/61


Antenna Radiation (Cont.) According to Maxwell

equation,

electromagnetic wave

radiation can be

generated if alternatecurrent is present in the

conductor. The radiation

capability is related to

the length and shape of

the conductor.

A

C

B


18/61


Antenna Radiation (Cont.)

The straight conductor that can generate intensiveradiation is called dipole.

If the length of the two arms of a dipole is 1/4

wavelength, the dipole is called symmetrical dipole

Dipole1/2

1/4

1/4

1/2

Wavelength()

900MHz -> : 166mm

1800MHz -> : 83mm


19/61



Symmetry

Dipole Radiation

Side view

Top view

Concentrat ion


20/61



1mW by one dipole 4mW by array of four dipole

6dB Gain


21/61



By reflection, radiation energy can be concentratedto single direction.

Omni: 4mW Directional: 8mW

Antenna

(Top View)

9dB Gain6dB Gain


22/61


Antenna Radiation

The more the dipole in one

antenna, the more

concentrated the radiated

energy, the higher the

Antenna Gain.

From one dipoleto

nine dipole, Antenna

Gainincrease from 0 to

9dBd.


23/61


Contents







24/61


Electric Specifications


25/61


Frequency Range (Cont.)

Frequency Rangeis also calledAntennaBandwidth. Antenna works in specific range frequency. The Central

Frequency (fc)have the best performance, deviation offc

deteriorate the performance.

Two definition ofAntenna Bandwidth:3dB deterioration

ofAntenna Gainor VSWRtoo high, typically 1.5. The

later one is commonly used in wireless communication.


26/61


Frequency Range

Central Frequency850MHz is with best performance. Butwithin Bandwidth820MHz-890MHz, VSWR


27/61


Directionality

The Directionalityis the ability of Antenna to radiateelectromagnetic wave in a specific direction.

As to receiving, it is the ability to receive signal from

different direction. Directionalityisrepresented by

Antenna Pattern Diagram. Antenna Pattern Diagramshows the transmitting and

receiving ability of antenna at different direction of space.


28/61


Antenna Pattern (Cont.)

Horizontal pattern

Main Lobe

First Side

Lobe

Back LobeZero Point

Horizontal Half

Power Bandwidth

-3dB

Vertical pattern


29/61


Antenna Pattern (Cont.)


30/61


Antenna Pattern

Parameter Description

Zero Point Filling

When zero depth is -20dB or greater, and the

antenna is high, to ensure the coverage, zero

point filling is needed.

Half Power Lobe Width

Angle included by two direction of 3dB

deterioration than the max transmissiondirection.

Horizontal half power Lobe width and vertical

half Lobe width.

Side Lobe Suppression

Ratio

The ratio of the maximum main lobe power to

the maximum side lobe power.

Front-to-back ratio

The ratio of the maximum main lobe power to

the maximum back lobe power.

Back lobe cause interference.


31/61


Antenna Gain (Cont.)

Antenna Gainis an important antenna index, indicating

the antenna capability (directional antenna) of

concentrating energy into a certain direction.

Isotropic Antenna

Dipole Antenna

Practical Antenna

dBd

dBi

2.15dB

-70dBm-85dBm-87.15dBm

(15)

(17.15)


32/61


Antenna Gain

Relationship betweenAntenna Gain Ga, Horizontal Half

Power Lobe Widthand Vertical Half Power Lobe Width

:

32400log10

aG


33/61


Downtilt Angle (Cont.)

Electric Downtiltand Mechanical Downtilt. Generally, the

former is better, but expensive.

No Downt i l t MechanicalElectr ic

Distor t ion


34/61


Downtilt Angle

Electric Downtiltand Mechanical Downtilt. Genarally, the

former is better, but more expensive.

10oElectr ic 10

oMechanical6

oElectr ic +

4oMechanical


35/61


Others

Parameter

Description

Port Isolation

For the antenna with multiple ports, such as dual

polarization antenna, the isolation between the ports for

both transmission and reception must be greater than 30dB

Power Capacity

The max average power capacity.

For example, a single carrier is 40W, one port input eight

carriers, the total input of the antenna is 320W. Therefore,the power capacity of a single port must be greater than

320W.

Related to environmental temperature, typically tested

under 50 oC.

IM3

Third-order Intermodulation product.

Two TRX use f1 and f2, both input power 43dBm. TheThird-order Intermodulation product is 2f1-f2 and 2f2-f1,

the power of which should be less than, for example, -

150dBc or -107dBm.


36/61


Mechanical Specifications

Input Connector

Type

Working

Temperature

Working Humidity

Wind Load

Size and Weight


37/61


Contents







38/61


Overview

The antenna selection is very important. The selection

should consider actual conditions, such as coverage

requirement, traffic volume, interference, and QoS.

Antenna selection is closely related to coverage, so the

antenna application can be divided into four types

according to landforms or traffic distribution: Urban area,

Suburban area, Rural area, and Road area.


39/61


Problem in Antenna Selection

Landforms and Antenna Pattern.

Blind under tower.

Large Mechanical Downtilt.

Distortion ->

High Gain Antenna.

Size, Zero Point, Side Lobe

Polarization. Loss.

Interference


40/61


Downtilt Planning (Cont.)

Downtilt Angle decided by Half Power Lobe Width ,

Antenna High Hand Coverage Distance D.

2)arctan(

DH


41/61


Downtilt Planning

Antenna Type Vertical HalfPower Angle

Cellradius

R(m)

AntennaHeight (m)

Downtilt Angle(degree)

65 degrees, 15 dBi 15 250 30 14

65 degrees, 15 dBi 15 250 35 15

65 degrees, 15 dBi 15 250 40 17

65 degrees, 15 dBi 15 500 25 10

65 degrees, 15 dBi 15 500 30 11

65 degrees, 15 dBi 15 500 35 12

65 degrees, 15 dBi 15 500 40 12

65 degrees, 15 dBi 15 800 30 10

65 degrees, 15 dBi 15 1000 30 2


42/61


Urban Area

Sites are very dense in urban areas. The coverage area of each cell should be

as small as possible to reduce interference and enhance frequency reuse.

Parameter Requirement

Horizontal Half Power

Lobe Width:

Should be smaller value, 65typically.

Proper selection can reduce interference

Antenna Gain medium gain

15dBi (900MHz) and 15-18dBi (1800 MHz)

Antenna Polarization Consider the limited space in cities, Dual

Polarization Antenna is prefered.


43/61


Suburban Area

Because the environment is suburban areas are largely different from that

of urban areas, antennas used in suburban areas can be selected according

to the required coverage area.



Lobe Width:

65 or 90 can be selected

According to actual conditions.

Antenna type Omni antennas are not recommended for

smooth expansion in the future.


44/61


Rural Area

In rural areas, traffic volume is small and base station are sparsely

distributed, so some base stations are required to cover a large area.


Antenna type

Omni Antenna is recommended. If for wide coverage, high gain directional

antenna is required.


Lobe Width: If directional antenna, 90 is recommended .

Zero Point When high site for wide coverage, zero point

filling is necessary.


45/61


Road Coverage

To cover the areas along railways and highroads, a

directional antenna with narrow beams can be selected.

To cover the highroads and the villages scattered around

the highroads, an omni antenna can be selected.

To cover highroads only, an 8-shaped antenna can be

selected.

To cover the highroads and the towns on one side of the

highroads, the 210antenna can be selected.


46/61


Road Coverage (Cont.)


47/61


Road Coverage


48/61


ReferenceLandform Type Reference

Urban Directional Generally, select low or medium gains and preset electrical tilt

angle.

Suburban Directional Generally, select the antennas with high gain; both electrical

and mechanical tilt antenna are ok.

Plains &

Rural

Directional Generally, select the 90 antennas.

Omni Select the antennas with zero point filling.

Expressways

Directional First select the 8-shaped antennas, it is preferred to have zero

point filling function.

Directional

+ Omni

First consider the 210 antennas, and then consider using the

directional antenna and omni antenna together.

Mountain

Omni Moutain top, first consider the antennas with zero point filling

function, and then consider the antennas with low gain.

Directional Moutain side, first consider the antennas with low gain and

wide vertical beams.


49/61


Contents







50/61


Contents


1.1 Basics

1.2 Antenna system


51/61


Electric Downtilt Antenna

In Electric Downtilt Antenna, feeding network is used to

adjust amplitude& phase of input signal from different

path, so as to form radiation beam with a certain shape.


52/61


Classification

FET(Fixed Electric Downtilt)

Electric Downtilt is fixed

MET(Mechanical Electric Downtilt)

Electric Downtilt is changed by knoborpulling bar

RET(Remote Electric Downtilt)

Electric Downtilt is changed by OMC.

Add RCU(Remote Control Unit) to MET.


53/61


Contro l cable(DC+ contro l sig nals )

Pul l ing bar

MET and RET

MET

Radome

Pul l ing bar

Radome

RCU

RET


54/61


Contents


1.1 Basics

1.2 RETAntenna system


55/61


RET Antenna System

BTS

RCUSBT

Antenna

OMC

BSC

BT

BTS

RCUSB T

Antenna

BT


56/61


Component

RCU(Remote Control Unit)

motor driving and controlling unit for antenna.

Receive and execute command from BTS, drive the motor

which drives the adjustable phase shifter, so as to change

the downtilt.

SBT(Smart Bias-Tee)

Abstract DC (power source) and controlling command from

feeder.

Provide DC and controlling command for RCU.

BT(Bias-Tee)

Couple DC and controlling command into feeder.


57/61


RCU

Motor

Port 2 to

cascading RCU

Port 1 to

SBT

AntennaAntenna Antenna

BTS

RCUSBT

RCU

Sector 1

RCU

Sector 2 Sector 3

BT


58/61


BT

DC/OOK

RF

OOK

DCRF

Port 1 to feeder/antenna

Port 3 to DATU Board

RF signal DC signal OOK signal

Port 2 to BTS

B ias Tee


59/61


SBT

Smart B ias Tee

RF

signal

DC

signal

OOK

signal

Port 1 to AntennaPort 2 to Feeder

Port 3 to RCU

RS485

signal


60/61


Summary

In this course, we have learned:

Antenna working principles

Important Antenna specifications

Choose correct type of antenna in different situation

Electric Downtilt Antenna


61/61

Thank youwww.huawei.com

OMP110030 Antenna Basics ISSUE1.02

Documents