Radio Frequency Parts and Antenna

OMF000004 Radio Frequency Parts and Antenna ISSUE1.0

Huawei Technologies Co., Ltd.


Table of Contents

Table of Contents Course Description.................................................................................................................. 1 Course Introduction.......................................................................................................

1

Course Objectives........................................................................................................... 1 Chapter 1 Combiner/splitter Unit............................................................................................ 2 1.1 Overview.................................................................................................................. 3 1.2 CDU......................................................................................................................... 5 1.3 SCU......................................................................................................................... 7 1.4 EDU......................................................................................................................... 8 Chapter 2 Outdoors Antenna Feeder System................................................................... 10 2.1 Overview..............................................................................................................

11

2.2 Antenna.................................................................................................................. 12 2.3 Tower Mounted Amplifier.....................................................................................

28

2.4 Feeder..................................................................................................................

32

i

Course Description


Course Description Course Introduction This training material is for the product of Huawei M900/M1800 BTS system.This course includes combiner/divider unit and outdoors antenna feeder system. This course introduces the principles of CDU, SCU and EDU, the basic knowledge of antenna as well as their applications.

Course Objectives After completion of this course, you should be able to: 

Master CDU structure, pinciple and functions.



Master antenna’s main technical indices.



Master the knowledge about tower mounted amplifier and feeder.

1


Error! Style not defined.Error! Style not defined.

Chapter 1 Combiner/splitter Unit

Combiner and splitter Unit



Introduction



CDU



SCU



EDU

2



1.1 Overview 1.1 Introduction

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

3



1.1 Introduction

Function 

of Combiner and Splitter：

Using one antenna support multi TX/RX signals,

decreases

the

amount

of

antenna and feeder 

Complete TX/RX duplex and combine TX signal



Filter, amplifier and split the RX signal



Provide power for TTA

4



1.2 CDU 1.2 CDU（Combining Distribution Unit） Tx1 

Tx2

Tx_Comb Tx_Dup Rx1 Rx2 Rx3 Rx4 HL_out Rx5 Rx6 Rx7 Rx8 HL_in RxD_out

Tx/Rx_ANT

combiner

duplex

splitter amplifier splitter filter RxD

CDU Function: 1. Combiner function 

Combiner part is to combine two carrier frequencies and output it to antenna port. When the number of carrier frequencies is more than 2, SCU may be used. The combiner’s insert loss is 4.5dB (4.5dB refers to the attenuation nearby the central band; the total loss in the whole band is not more than 5.5dB).



. Because it is hybrid combination, it has a whole-band bandwidth and can support RF hopping

2. Divider function 

Divider part consists of two tributaries: main receive and divisity receive.



When the number of carrier frequencies is more than 4, the divider can be cascaded into a 1-to-8 divider.

3. Detection and alarm function 

CDU has standing wave detection function, realizing the status monitoring of antennas and feeders. When it detects that the standing wave exceeds the preset threshold (1.5:1 or 2.5:1), CDU will give the corresponding alarm signal and indication.

5





When the internal amplifier or thei tower mounted amplifier is abnormal, CDU will report the alarm signal to OMU.

When CDU is used together with SCU and the number of cell carrier s is not more than 8, we can use 2 feeders and one bipolo antenna) to realize the signal receive/transmit.

6

antenna (or 2 single-polarized



1.3 SCU 1.3 SCU （Simple Combining Unit）

combiner TX1

combiner

TX2 TX3 TX4

combiner TX-Comb

Simple combiner unit (SCU) complets 4-carrier-frequency combiner output function together with CDU. 4 carrier frequencies form one output with three 3dB-bridges, and the insert loss is 6.8dB.

7



1.4 EDU 1.4 EDU（Enhance Duplexer Unit） Tx1

Rx1 Rx2

Rx1 Rx2

duplex

Tx/Rx_ANT1

duplex

Tx/Rx_ANT2

splitter amplifier

splitter amplifier

Tx2

EDU is applicable for wide coverage with diversity receive function. 1 EDU can support receive/transit of 1 or 2 carriers.

8



Comparison among different RF unit combine mode CDU

SCU

SCU+CDU

EDU Double CDU( with combine) Double CDU (without combiner)

combine two TX signal one step 3dB combiner combine four TX signal two step 3dB combiner combine four TX signal two step 3dB combiner no combiner double duplex no combiner double duplex combine two TX signal double duplex

typical loss value of TX(dB)

price comparison (per TRX)

4.5

middle

6.8

low

8

low

1

middle

1

high

4.5

middle

The typical CDU configuration solutions

1) Basic solution: CDU+SCU (price priority) 2) When wide coverage is demanded and the number of the carriers is not more than 2: EDU Solution The limitation of using EDU: 

EDU is only applicable for the sector with less than 2 carriers, and it might be replaced in case of expansion.



EDU’s purchase cost is slightly higher than that of CDU.

Suggestion for using EDU: 

It should be used only in the area with the less possibility of expansion.



It is not recommended in urban area. If 2-carrier-frequency wide coverage is required in the urban area, double-CDU application is recommended.



For the ordinary directional site, the loss of combiners in each sector should be consistent, EDU CDU and SCU should not be used mixedly in the same site. Otherwise concentric circle technology should be used.



Only in the area with wide coverage requirement is EDU adopted.

In case of above 3 carriers in the cell and wide coverage: Dual CDU solution.

9


Chapter 2


Outdoors Antenna Feeder System

Outdoor RF device



Introduction



Antenna



Tower Top Amplifier



feeder

10



2.1 Overview 2.1 Introduction RF device of BTS Jumper/TTA Connector (DIN) DIN connector

Dual polarization antenna

Lightning arrester TTA

jumper

Antenna connector （DIN） Lightning arrester/feeder connector（DIN） Jumper connector（DIN）

BTS rack

11

Jumper/TTA connector （DIN）



2.2 Antenna 2.2 Antenna 1、Introduction  function 

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

 Antenna 





type

Classify by working band ： VHF, UHF, Microwave, etc Classify by radiate pattern：omni antenna, direction antenna Classify by structure ： line paraboloidal antenna

12

antenna,



2.2 Antenna 2、Main specification  pattern

Omni ant enna l obe

Di rect i on ant enna l obe

The antenna pattern: the diagram of the antenna’s radiation electromagnetic field distributed along the angle coordinates in the fixed length. It can be divided into field strength antenna pattern, power antenna pattern and phase antenna pattern, respectively, reprensented with radiation field strength, power density and phase.

1) In the antenna pattern, the radiation lobe containing the maximum radiation direction is called antenna main lobe, or antenna beam. The lobes except the main lobe are called side lobes or border lobes; the side lobe in the reverse direction of main lobe is called back lobe. The the following parameters are used usually: 

Zero power lobe width: the angle between two zero radiation directions at two sides of main lobe maximum value.



Half power lobe width: the angle between the directions that the maximum value the field strength decreases to 0.707 time of it (3dB).



Side lobe level: the ratio of Side lobe max value to main lobe max value.



Back front ratio: the ratio of main lobe max value to back lobe max value.

13



2.2 Antenna  Gain 

One important characteristic of antenna, it equals

that

the

factor

of

direction multiplied

by

efficiency ,and it represents ability of TX/RX. 

Unit: dBd、dBi

l / 2 ant enna Direction antenna

dBd

theory source dBi

dBi=dBd+2.15 Gain is one of the most important parameters in antenna system, and is related to omni antenna or dipole antenna. See the above figure. dBi refers to the reference value between directional antenna and omni radiator. dBd refers to the reference value comparing with dipole antenna. The relation is: dBi=dBd+2.15.

14



2.2 Antenna  HPBW:

Half power bandwidth



Lobe angels between two point, the power of which reduce to the half of that of the maximum radiate direction.



Vertical HPBW/Horizontal HPBW



Normally we refers to horizontal angel, for example : 65 degree, 90 degree, 120 degree

 F/B:

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

15



2.2 antenna  polarization 

The direction of electro-vector polarization

antenna

usually

radiated by antenna. Dual adopts

+45/-45

degree

orthogonal polarization. Vertical antenna adopt vertical polarization. 

The vertical polarization wave is vertical with the plane of ground, and the horizontal polarization wave is parallel with the plane of ground



One antenna has only one polarization direction. Dual polarized antenna contains two single-polarized antenna in one entity

1 ）

Polarization is a radiation feature, describing electromagnetic wave field vector direction; when there is no special description, the electric field vector space direction is the polarization direction of electromagnetic wave, in the maximum radiation direction of the antenna.

2) The eletric field vector direction keeping unchanged at any time is called straight line polarized wave, and sometimes it is referredto the ground. That the wave of the electric field vector direction paralleled the ground is called horizontal polarized wave; and that the wave of the electric field vector direction is vertical to the ground is called vertical polarized wave.The horizontal polarized wave is vertical with the incidence plane, so, it is also called orthogonal polarized wave. The vertical polarized wave is parrallel with incidence plane, so, it is also called parrallel polarized wave. Electric field vector and propagation direction constitute the polarization plane. 3) Sometimes the electric field vector direction is not fixed. If the track formed by the electric field vector point is a circle, it is called circle polarized wave; if the track is the ellipse, it is called ellipse polarized wave.Ellipse polarized wave and circle polarized wave are rotative. 4) Either ellipse polarized wave or circle polarized wave can be formed by two orthoganal line polarized waves. If their amplitutdes are the same, they will be

16



combined as a circle polarized wave; otherwise, they will be combined as a ellipse polarized wave. The antenna may radiate the unnecessary energy in the un-expected polarization direction. This kind of unnecessary energy is called radiation component of cross polarization. For the line polarized antenna, the cross polarization is vertical with the preset polarization direction. For the circle polarization antenna, the rotating direction of cross polarization is reverse to that of preset polarization. So, cross polarization is called orthogonal polarization.

17



2.2 antenna  Port 

isolation The isolation among ports should be more than 30dB for multi port antenna, such as dual polarization antenna, dual band dual polarization antenna.

 Power 

 Null

capacity

Antenna can bear the max. power that antenna can work long time. Because antenna contains matching, balance, phase shift and coupling devices, the bearing power of these device is limited filled



It may be need null filled technology applied when zero depth is less than main beam for –26dB.



High gain antenna especially adopt null filled antenna to effectively improve the nearby converge

1) Port isolation For multi-port antenna, such as dual polarization antenna, dual-band dual polarization antenna, the isloation between the ports in case of receive/transmit should be more than 30dB.

2) Power capacity Refers to average power capacity. The antenna includes other coupling devices such as match, balance and phase shift, etc, and its power is limited. Considering the actual maximum input power (the single carrier power is 20W), if one port of the antenna can input maximum 6 carriers, the input power of the antenna is 120W. So, single port power capacity of the antenna should be more than 200W (in case of 65oC environment temperature).

3) Zero point filling If formation beam design is adopted in BTS antenna vertical plane, the first zeropoint of the the lower side lobes should be filled against distinct zero depth so as to make rediation level in the service area be more symmetric.Generally, if the difference of zero depth to main beam is greater than –26dB-, it indicates that the antenna has zero-point filling; for wide coverage antennas, this is not required.High

18



gain antenna especially needs to adopt zero point filling technology to effectively improve the near-site coverge.

19



2.2 antenna  Upper   PIM 

side lobe suppression

This index should be less than -18dB (passive inter modulation ) PIM should be satisfy -150dBc

 Antenna 

size and weight

the antenna size should be as small as possible, and its weight should be as light as possible in case that the electrical indices can meet the requirements.

4) Upper side lobe suppression For the micro cell cellular system, to improve the frequency multiplexing capability and reduce co-channel interference on the adjacent cell, we should decrease the side lobe aiming at the interference area as much as possible , and improve D/U value. The level of the first upper side lobe should be less than –18dB. For the macro cell system, BTS antenna is not required like this.

5) Antenna input interface In order to improve the reliability of PIM and RF connetion, BTS antenna input interface adopts 7/16DIN-Female connectors. Before the antenna is used, the port should be equipped with the cover, to prevent from generating oxide and contamination.

6) PIM PIM: refers to the interactive modulation effects due to non-linear of the passive parts such as connector, feeder, antenna, filter and so on, in case that they work in multiple carrier frequency and large power signal condition. Especially, if the interactive modulation substances dropped in the receive band, they will seriously affect the receive performance of the system.

20



7) Antenna size and weight For the convenience of storage, transportation, installation and security, the antenna size should be as small as possible, and its weight should be as light as possible in case that the electrical indices can meet the requirements.

21



2.2 antenna  Wind



bearing capability

the antenna is required to work normally in case of 36m/s wind speed, and not to be damaged in case of 55m/s

 Temperature



-40℃～+65℃

 humidity



BTS antenna should work normally within the relative humidity of 0~100%

 Dampproof,

salt-mist-proof, and mildew-proof

8) Wind bearing capability BTS antenna is usually installed on the top of building or tower, especially, the coastal area with large wind speed, so, the antenna is required to work normally in case of 36m/s wind speed, and not to be damaged in case of 55m/s.

9) Temperature and humidity BTS antenna should be working normally in –40oC~+65oC.and within the relative humidity of 0~100%.

10)

Lightning protection

All RF input ports of BTS antenna are required to be DC direct grounded.

11)

Dampproof, salt-fog-proof, and mildew-proof

BTS antenna should be Dampproof, salt-fog-proof, and mildew-proof. BTS omni antenna should be allowed antenna reverse installation, and meet the above requirements.

22



2.2 antenna 3、distributing antenna system Small antenna Power splitter

Small antenna

coupling

Small antenna

coupling

Small antenna Small antenna

Dual direction coupling

amplifier

BTS BTS

coupling coupling

Power splitter

Dual direction amplifier

Power splitter

Small antenna

Small antenna

With the development of GSM system, the mobile communication network is much highly required. In order to realize the excellent coverage in the special areas such as big building, highway/railway tunnel, subway, etc, the distributed antenna system is required. As shown in the above diagram, the downlink signal from BTS goes into the distributed antenna system , forms multiple tributaries after downlink power splitter, and each tributary can be divided more smaller branches after a second power splitter. At the end of each branch, a small antenna is connected, and each small antenna covers a certain area. When the signal strength is not enough, a bidirectional amplifier can be used. In the opposite derection, the uplink signal from each branch undergoes small antenna, power splitter, bi-directional amplifier, and arrives at the BTS via the interface. In the above system, the signal transmission channel and the distribution can be coaxial cable and RF power splitter, or optical link. Or the mixture of coaxial cable, power splitter and radiation antenna: the leaking cable. The distributed antenna system includes: coaxial feeder distributed antenna, optical fiber feeder distributed antenna, leaking cable, etc.

23



2.2 antenna 3

3 3 1.3

3

6

3

Dual direction Tx/Rx

3

amplifier Dual direction amplifier

0.5

3 3

0.5

10

10

33

3

3 Tx/Rx

In order to decrease the loss, 7/8’’ feeder (with smaller loss) should be used in the backbone. In the tributary, 1/2’’ super flexible cable should be used.

24



2.2 antenna  The

optical fiber repeater is mainly adopted in the case of wide coverage and long distance transmission Optical transceiver transceiver

signal

Optical transceiver

transceiver

Optical transceiver Optical transceiver

25



2.2 antenna

Leaking It

fiber

is mainly adopted for tunnel, metro, and with high

cost of equipment and installing Dual direction amplifier

Power splitter

Matching load

Tx/Rx

Dual direction amplifier

26

Matching load



2.2 antenna  

Comparison with three kinds of of distributed antenna type

leaking fiber

coaxial fiber

optical

design agility

good

good

not good

cost

high

low

high

complexityof installing

high

low

low

loss of transmission

high

high

low

power supply

not needed

not needed

needed

reliability

high

high

low

applicability

metro,tunnel

high building, commercial area

far area coverage

27



2.3 Tower Mounted Amplifier 2.3 TTA

Simplex TTA

duplex TTA

triplexTTA

triplex TTA TX filter BTS

antenna

bypass

Bias Tee RX filter

RX filter Low noise amplifier

DC

Tower mounted amplifer is mainly used to improve the sensitivity of the system and improve uplink coverage distance. According to the requirements of antenna feeder system, simplex, duplex and triplex tower mounted amplifier can be selected. In Huawei antenna feeder system, the tower mounted amplifer is optional. For the convenience of maintenance and expansion in the future, the newly added BTSs or the expansion BTSs should adopt triplex tower mounted amplifier.

28



2.3 TTA Notice:  Turn 

on power of TTA in CDU before install

TTA switch is in rear panel of CDU

 Configuration 

TTA current switch is in rear panel of CDU

 Configuration 

alarm threshold of TTA current before install attenuation factor of receive signal on consol

attenuation factor of receive signal =TTA gain –feeder loss

 Simplex  Don’t

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

use TTA if nor necessary



For the convenience of installation



To get better lightening-proof effect

29



2.3 TTA

Rear

panel of KMW CDU TTAD

OFF

OFF

TTAM

TTAD 1 2 3

TTAM TTAD OFF

TTAM

OFF

TTAM TTAD

select current limit

1 2 3

30

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



2.3 TTA

panel of COM DEV CDU

1 2 0 3 3 2 1 0

0 3

3

2 1 0

0 3

1 2

1 2

3

2 1 0

Note: MAIN：main TTA switch DIVERSE：diversity TTA switch

DIVERSE MAIN

Rear

31



2.4 Feeder 2.4 FEEDER  Feeder  





selection Type : 1/2”、7/8”、5/4” Select 5/4” in case of feeder length is more than 80 m and otherwise select 7/8” in 900MHz Select 5/4” in 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

(MHz) VSWR Bend LOSS dB/ 100m ， Radi us ( m) manuf act urer 890 1,000 1,700 2,000 LDF5-50A(7/8 ) 4.03 4.3 5.87 6.46 1.15 0.25 ANDREW LDF6-50(5/4 ) 2.98 3.17 4.31 4.77 1.15 0.38 ANDREW M1474A(7/8 ) 4.3 6.6 1.15 0.22 ACOME SYFY-50-22(7/8) 4.03 5.87 6.46 1.15 0.3 609 HFC22D-A(7/8) 4.47 6.7 1.15 0.25 LG TYPE

32

Radio Frequency Parts and Antenna

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