OMF000004 RF parts and Antenna ISSUE2.0

RF device in BTS includes two parts  Indoor: combiner and splitter unit For example: CDU module, SCU module and EDU module  Outdoor: antenna, feeder, TTA tower top amplifier, jumper

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OMF 000004 Radio Frequency Part and Antenna

ISSUE 2.0

RF components are widely used in wireless system, and effect performance

of network

 Master the key specifications of antenna

 Be able to choose the suitable type of RF

component

Chapter 1 RF Part in BTS

Chapter 2 Antenna Chapter 3 Feeder and TTA

5 Internal Use

Antenna

TTA

Antenna stand

Jumper between antenna and TTA

Jumper between TTA and feeder

Feeder

Lightening arrester

Jumper between lightening arrester and cabinet

BTS312 cabinet

SWITCH BOX FAN BOX

AIR BOX

P S U

P S U

P S U

P S U

P S U

P S U

P M U

T M U

T E S

T E U

T E U

C D U

C D U

T R X

T R X

T R X

T R X

C D U

C D U

T R X

T R X

T R X

T R X

C D U

C D U

TDU

FAN BOX AIR BOX

P S U

P S U

P S U

P S U

P S U

P S U

P M U

T R X

T R X

T R X

T R X

RF Device of BTS

RF device in BTS includes two parts

 Indoor: combiner and splitter unit

For example: CDU module, SCU module and EDU module

 Outdoor: antenna, feeder, TTA (tower top amplifier),

jumper and lightning arrester

7 Internal Use

Function of Combiner and Divider

 Use one antenna to support multiple TX/RX signals, decreases the amount of

antenna and feeder

 Complete duplexer of TX/RX and combine

TX signal

 Filter, amplify and split the RX signal

 Provide power for TTA

CDU (Combining and Divider Unit)

Tx1 Tx2

Tx_Comb Tx_Dup

Rx5 Rx6 Rx7 Rx8 HL_out

HL_in RxD_out

RxD Tx/Rx_ANT

EDU (Enhance Duplexer Unit)

divider

amplifier

Rx1 Rx2

Tx/Rx_ANT1

divider

amplifier

Rx1 Rx2

duplexer Tx/Rx_ANT2Tx2

11 Internal Use

Comparison among Different Combining Units

combine mode

typical loss value of TX(dB)

price comparison (per TRX)

CDU

combine two

TX signal one step 3dB combiner

4.5 middle

SCU

combine four

TX signal two step 3dB combiner

SCU+CDU

combine four

TX signal two step 3dB combiner

New Type CDU&ESCU

 The structure is the same as CDU's, but increase MAX input power It can bear up to100W input RF power

 The structure is the same as CDU's, but increase MAX input power It can bear up to100W input RF power

13 Internal Use

Chapter 1 RF Part in BTS Chapter 2 Antenna

Chapter 3 Feeder and TTA

What is Antenna?

Radiate and receive radio wave ,convert high frequency current to electromagnetic wave when transmitting, and convert electromagnetic wave to high frequency current when receiving

B l a h b l a h

b la h b l a h

15 Internal Use

Classification

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

 Classify by radiate pattern: omni, directional

 Classify by structure: line, pane, parabola feed

 Classify by polarization: vertical and horizontal

 Classify by outline: line and pane

omni direction directional Antenna

Radiate Pattern

17 Internal Use

Outline

vertical polarization Omni antenna

dual polarization directional antenna

Polarization

vertical polarization directional antenna

Antenna can not amplify the transmission power, just

concentrate RF power to one direction

Radiate Pattern

Omni antenna lobe

Direction antenna lobe

21 Internal Use

Radiate pattern

Dipole and Isotropic

23 Internal Use

Gain

 The radiation ability of certain antenna overtop dipole or isotropic

 Indicates the antenna feature of electromagnetic radiation in

dBi =dBd+2.15

Forward to Back Ratio

 The ratio of main lobe signal strength to back lobe

 This value is within 18—45dB In urban, it is suggested to use the antenna with high F/B ratio

25 Internal Use

Beam Angle

 HPBW: Half Power Beam Bandwidth

 Lobe angel between two points, the power of which reduce to

the half of that of the maximum radiate direction

 Vertical HPBW and Horizontal HPBW

Down title

To control coverage

To decrease inter modulation

Realization: electron and mechanism

27 Internal Use

Down title

Effect of Electron Down title

29 Internal Use

Effect of Mechanism Downtitle

Effect of different methods

31 Internal Use

Polarization

 The direction of electro - vector radiated by antenna The vertical polarization wave is vertical with the plane of ground, and the horizontal polarizatio

n waveis parallel with the plane of ground

 Single antenna has only one polarization direction

 Dual polarized antenna contains two single - polarized antenna in one enti

ty Dual polarization antenna usually adopts +45/ 45 degree orthogonal polarization

-Polarization

33 Internal Use

Dual Polarization

Main to lower side Main to upper side

Upper Side Lobe Suppression

 Sufficient decoupling distance: 5-10λ

 Antenna patterns become superimposed if distance is too close

G1 、 G2: gain

Distributed Antenna System

BTS

BTS Power Power splitter

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

33

3

3

33

Dual direction amplifier

Dual direction amplifier

Optical Fiber Distributed Antenna

 The optical fiber repeater is mainly adopted in the case

of wide coverage and long distance transmission

43 Internal Use

Leaky Cable

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

Dual direction amplifier

Dual direction amplifier Power splitter

Leaky cable

 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

45 Internal Use

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)

How to calculate strength with leaky cable?

Comparison with Distributed Antenna

type leaking fiber coaxial fiber optical design agility good good not good

cost high low high Complexity of

installing high low low

loss of transmission high high lowpower supply not needed not needed needed reliability high high low applicability metro, tunnel

high building, commercial area

far area coverage

47 Internal Use

Chapter 1 RF Part in BTS Chapter 2 Antenna

Chapter 3 Feeder and TTA

Tower Top Amplifier

 Amplify uplink weak signal, then:

 Balance uplink and downlink

 Compensate loss of feeder

Simplex TTA duplex TTA triplex TTA

49 Internal Use

Triplex Tower Top Amplifier

Low noise amplifier

Data Configuration of CDU

 Turn on power of TTA in CDU before installation

 TTA switch is in rear panel of CDU

 Configuration alarm threshold of TTA current before installation

 TTA current switch is in rear panel of CDU

 Configuration attenuation factor of receive signal on consol

 attenuation factor of receive signal =TTA gain – feeder loss

 Simplex TTA gain:14dB, triplex TTA gain:12dB

 Don’ t use TTA if not necessary

 For the convenience of installation

 To get better lighting -proof effect

51 Internal Use

Power Switch and Current Limit

OFF OFF

1 2 3

TTAM TTAD

OFF OFF

1 2 3

TTAM: power switch of main TTA switch TTAD: power switch of diversity TTA

select current limit

TTAM TTAD

Power Switch and Current Limit

DIVE

RSE

0 1 2 3 0 1 2 3

53 Internal Use

Feeder

LG 0.25

1.15 6.7

4.47 HFC22D -A(7/8 )

609 0.3

1.15 6.46

5.87 4.03

SYFY -50 -22(7/8 )

ACOME 0.22

1.15 6.6

4.3 M1474A(7/8 )

ANDREW 0.38

1.15 4.77

4.31 3.17

2.98 LDF6 -50(5/4 )

ANDREW 0.25

1.15 6.46

5.87 4.3

4.03 LDF5 -50A(7/8 )

2,000 1,700

In this course, we have learned:

 CUD structure and loss

 SCU structure and loss

 Antenna type and feature

Summary

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