RF Basic - Components and devices.ppt

8/10/2019 RF Basic - Components and devices.ppt

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BASIC RF

Components


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OBJECTIVES:

Review the Basic Units, terminology

and RF components

Applications


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COURSE OUTLINE:

I. Basics of Telecom

a. Transmitter

b. Receiver

c. Information

II . Terms and Units

a. Relative and Absolute

i. Ratios

ii. Logarithmic


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b. Amplitude and Signal Level

i. Watt

ii. dBm

iii. 3 dB point

iv. Losses and Gains

v. C/I or S/Nc. Frequency

i. Hertz

ii.Center Frequency

iii. Bandwidth

d. SPECTRUM ANALYZER


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e. Newtons Law

III. RF Components

f. Law of Conservation of Energy

a. active

b. passive

c. basic RF Componentsi. antenna

1. types

2. practical requirements

3. diversity


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1. Low Pass Filter

2. High Pass Filter

3. Band Pass Filter

4. Band Stop/Notch Filter

iii. Amplifier

iv. Attenuator

ii. filter

vi. Coupler

vii. Splitter/Divider

v. Circulator


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viii. Resistive Load

ix. Cable

x. Connectors

xi. Leaky Cables

e. Complex RF Component

i. Combiner

ii. Duplexer

iii. Diplexer

- Nokia RF Components

AFE & RTC


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IV. Implementation

a. BTS

b. Repeaterc. DAS

V. Link Budget

VI. Practical Limitationa. Hopping

b. Losses

c. Size

d. Cost

e. O&M

f. Reliability


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I. Basic of Telecom

a. Transmitterthe equipment that generates andamplifies a RF carrier signal, modulating the

carrier signal with intelligence, and feeding the

modulated carrier to an antenna for radiation into

space as electromagnetic wave.

b. Receiveran equipment used for receiving

radio waves and converting them into the original

intelligence

c. Information/Intelligencethe actual message

that is being sent in a communication system.


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Hi! Good

Morningtoo.

Hi! Good

Morning.

Tx

Rx


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II. Terms and Units

a. Relative and Absolute

i. Ratiosunits which are in absolute form and

represent division of values. Ex. C/I, S/N, etc.

ii. Logarithmicunits which are converted into

its equivalent logarithmic values. Ex. decibel

b. Amplitude or Signal Level

i. Watts

- it is named after the Scottish inventor

James Watt

- the SI unit of electric power that inone second gives rise to energy to one joule.

- signifies the strength of the given signal


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Amplitude

Amplitudethe value of a varying signal at a specific period

in time


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ii. Decibela power measurement unit referred to another

unit.

dBmthe power level of a certain signal taking 1

milliwatt as the reference

iii. Losses and Gains -energies that are either

added/absorbed and subtracted/released in a system

iv. C/I or S/Nthe ratio of the desired signal to the

undesired signal or interference/noise

- this is a measure of the strength of a

signal compared to any unwanted

signal.


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c. Frequency - the number of complete cycle per unit of

time for a periodic quantity such as alternating current,

sound waves and radiowaves.

i. Hertzthe SI unit of frequency equal to cycle

per second

T

Frequency =1

Period ( T )

=Vel of PropagationFrequency


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v. 3 dB pointsHalf power points

- points on the waveform where of

the maximum signal is located

- this is the reference when we take the

bandwidth of a certain waveform

Max pt.

3dB pt

Bandwidth

amplitude

frequency


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ii. Center Frequency - the average frequency of the

emitted wave when modulated by a symmetrical signal

iii. Bandwidththe range of frequencies which havebeen specified as performance limits for a filter, amplifier

or attenuator, defined as the 3dB points at the high pass

and low pass ends of the frequency response curve

CF

Bandwidth


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Spectrum Analyzer - an instrument

that measures the amplitudes of the

components of a complex waveformthroughout the frequency range of the

waveform.

d. SPECTRUM ANALYZER


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Spectrum analyzer


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e. Newtons Laws

i. First LawLAW OF INERTIA

-

- there is no change in motion of a body

unless acted upon by a resultant force.

ii. Second LawLAW OF ACCELERATION

- a body being subject to a resultant force

experiences an acceleration in the direction of

the resultant force.

iii. Third LawLAW OF INTERACTION-for every force acted on a body there is a force

equal in magnitude but opposite in direction


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f. Law of Conservation of Energy

- this states that energy can neither be

created nor destroyed, instead it will

just transform from one form toanother.


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IV. RF COMPONENTS

a. Active - components that introduces

additional energy and reprocess the received

signal

b. Passivecomponents that do not introduce

any additional energy on the signal.


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c. Basic RF Components

i. ANTENNA - a device that radiates and receives

radio waves

- British term is AERIAL

- they transition point in the

communication chain, where the signal

changes from a wireline signal to a radio

wave propagating signal and vice versa.

Types

Omnidirectional antennas: radiate with the same intensity to

all directions (in azimuth)

Directional antennas: main radiation energy is concentrated

to certain directions

- sometimes called RADIATOR


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antennas

yagi

radiation pattern

pico

panel


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a. Practical Requirements

i. Number of Antenna - reduce the required

number of antenna relative to the number of

radios. One to one ratio of antenna to radio is

impractical.

ii. Antenna isolationthe separation

between two antennas that is usually

considered when employing a spacediversity technique. The distance should be

multiple of the half wavelength.


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Antenna Isolation: Vertical

K

A

The following is valid for 900 Mhz.,

1800,1900Mhz and co-located 900 + 1800/1900

Mhz.

Requirements: Tx -Rx and Rx- Tx: 30 dB

Pre-condition: No influence from tower

structures More than 2m bet Ant and tower.

( A in figure)

Vertical Separation: Tx - Rx and Rx - Tx

Minimum 0.2 m

( K in figure)


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Antenna Isolation: Horizontal

D

Requirements: Tx -Rx and Rx- Tx: 30 dB

Vertical Separation: See Table Below

Table: Horizontal Separation

Gain dBi 900 Mhz 1800/1900 900+1800/1900

10 5m 2.5 m 1m


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There is a need for receiver diversity in cellular systems

to improve the uplink.

Space Diversity

TX1/RXA TX1/RXA

BTS Equipment

Common

TX/RX

Antenna

dd

Horizontal Separation, dd

for diversity = 12-18 (wavelength)

for isolation = 30 dB = 2 (wavelength)

[antennas with 65 degrees beamwidth,

all gain values]

DIVERSITY


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Polarization Diversity using dual-polarized antennas

vertical + horizontal polarization +/- 45 degrees polarization

vertical

array

horizontal

array

antenna

housing

connectors

feeders

+45

degrees

- 45

degrees

DIVERSITY


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Polarization Diversity using dual-polarized antennas

1.5 dB downlink loss

TX1/RXA TX1/RXA

Required isolation >30 dB between

the two antenna parts...

DIVERSITY


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ii. Filters - a selective device that allows a

desired range of energy to pass throughand substantially attenuating all other

ranges.

- they are used to separate, combine orsuppress microwave frequencies.

- they are used to ensure that noharmonics are transmitted


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1. Low Pass Filtera filter that

attenuates frequencies higher than

the cut-off frequency

fcInput Output

Amplitude Amplitude

Frequency Frequency


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2. High Pass Filter -a filter

that permits frequencies

higher than the cut-offfrequency.

Amplitude Amplitude

Frequency Frequency

fcInput Output


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3. Band pass Filter - a filter that

accepts a band of

frequencies andconsiderably attenuates

higher and lower frequencies

than the desired band.

Amplitude Amplitude

Frequency Frequencyfc fc

Input Output


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4. Band stop/Notch Filter - a

filter that prohibits the

passage of a certain

band of frequencies and

allows other

frequencies.

Amplitude Amplitude

Frequency Frequencyfc fc

Input Output


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iii. Amplifier - a device that

increases the strength of a

signal without appreciably

altering its characteristic

waveform.

Input Output

Time

Amplitude

Time

Amplitude


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iv. Circulator - a waveguide component that has a number

of terminals so arranged that energy entering one terminal

is transmitted to the next in a particular direction. This canbe used as a duplexer


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v. Directional Coupler - a device that

couples a secondary system only to a

wave traveling in a particular

direction while completely ignoringthe wave traveling into the opposite

direction


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vi. Splitter/Divider - a device that has

the capability to distribute one input

signal to two or more outputwithout introducing distortion to the

signal.


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vii. Resistive Load - component that can absorb the

transmitted energy and behaves like an actual load such

as an antenna.


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attenuator

viii. Attenuator - a device that uses resistive

components to reduce the strength of a

signal without introducing considerable

distortion.

Time Time

Amplitude Amplitude


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ix. Isolator - allows a signal to pass through in one

direction and attenuates it in the other direction. This is

usually used to prevent a very high SWR.

Incident Wave

Reflected Wave


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ables

xi. Cables - a transmission linewhere energy can pass through

without considerable decrease

on the energy


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xii. Leaky Cables - a cable which has a leak where

energy escapes out continuously

d Complex RF Components


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i. Combiners are needed to enable more than

one transmitter to be connected to one

common transmitting antenna.In GSM, two different TX combiners can be

used -

FILTER COMBINER

HYBRID COMBINER

Transceiver 1

Transceiver 2

Transceiver 3

Transceiver 4

d. Complex RF Components


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NOKIA Combiners

AFE - Antenna Filter Extension Unit- can combine 2 TRX per AFE but 2 AFE canbe used for every sector, this configuration is

called Dual Duplex Operation

RTC - Remote Tune Combiner

- one RTC can combine up to 6 TRX

- this combiner can support both RF andBASEBAND Hopping

- can ONLY support BASEBAND Hopping

- sometimes called WIDEBAND Combiner


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REMOTE TUNE COMBINER

CombinerPart

TX1

TX2

TX3

TX4

Duplex

Filter ANTENNA

Test Out

Rx Out

D-bus In

D-bus out

POWER

CONTROLLER PART

Rx OutRx Out

Pf Pr M

Main Functional Part of the RTCA (900)


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ii. Duplexer - a switching device that permits

alternate use of the same antenna for both transmit

and receive.

Tx

Rx


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Tx Filter

Rx Filter LNA

Antenna

Rx

Tx

Duplexer Block Diagram


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iii. Diplexer - a coupling system that allows two

different transmitters to operate simultaneously

or separately from the same antenna.

Tx1

Tx 2


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Diplexer Block Diagram

Port 900

Port 1800

Dual Band

Antenna


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vi. RECEIVER MULTICOUPLER UNIT (RMU)

- amplifies the received signals and divides them to the

receivers (Rx) of the Transceiver units (TRXs).

RX 1

RX 3

RX 4

RX 5

RX 6

RX 2

Amplifier

ModuleTest

Module

RX

Filter

ANT

TEST

Main Functional Part of the RMUA (1800)


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IV. Implementation

a. BTSBase Transceiver Station

- this is the outer most part of the networkand it interfaces the mobile subscriber to

the network

MS BTSMSC

BSC


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Duplexer

Transceiver

Transceiver

Transceiver

Transceiver

Tx

Tx

Tx

Tx

Rx

Rx

Rx

Rx

RMU

Combiner

Antenna

Base Transceiver Station


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REPEATER


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BPF BPF

BPFBPF

BPF

BPF BSF

BSF

ATT

ATT

Downlink

Uplink

PSU AlarmsTo BTS To MS

PA

PA

LNA LNA

LNALNA


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V. Link Budget

- this is a calculation of the

signal strength seen at the receiver

considering the output power of the

transmitter and the possible gains and

losses that might be incurred within

the system.


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Downlink Link BudgetMobile sensitivity = Bts transmit power - Combiner loss -

duplexer loss - Cable/feeder loss + Bts antenna gain - Maximum

path loss - fading margin - Building/Car penetration loss - body

loss + Mobile antenna gain

Uplink Link BudgetBts sensitivity = Mobile transmit power + mobile antenna gain -

body loss - Maximum path loss - fading margin - building/car

penetration loss + Bts antenna gain + - Duplexer loss- cable/feeder loss + Low Noise Amplifier

Gi


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Mobile sensitivity = -104 {GSM} / -100 {DCS}

BTS sensitivity = -107 {GSM} / -104 {DCS}Sensitivity refers to the receivers ability to receive the weakest signal.

Combiner loss = 3 dB {Filter combiner} / 5 dB {Hybrid combiner}

Main Cable/Feeder cable = 1.2 dB loss per 100 ft

Jumper Cable = 2.1 dB loss per 100 ft

Connector loss = 0.1 dB

Lightning arrestor loss = 0.1 dB

Duplexer loss = 0.5 dB

BTS Antenna gain = 16 dBd / 18 dBi

Mobile Antenna gain = 0 dB

Given:


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Car penetration loss = 6 dB {ETSI}

Building penetration loss = 20 dB {dense urban}18 dB {urban}

12 dB {suburban}

Body Loss = 3 dB {ETSI} / 5 dB {Ericsson}

LNA Gain = 5 dB


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Down Link

MS Sensitivity = 43 dBm3 dB0.5 dB3 dB + 8 dB120 dB

- 6 dB3 dB + 0 dB

= - 84.5 dBm

* The received power is within the MS sensitivity

BTS Sensitivity = 30 dBm + 0 dB3 dB120 dB6 dB

+ 8 dB3 dB +5 dB0.5 dB

= - 89.5 dBm

* The received power is within the BTS sensitivity

MS Sensitivity = PobtsLcomb- LdupLcab+ GantLpathLcarLbody+ Gant

BTS Sensitivity = Poms+ GantLbodyLcarLpath+ GantLcabLdup+ LNA -Lcoupler


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AntennaNavigation

Trigger

Power level

Power Level Diagram

BTS

CombinerLoss

DuplexerLoss

CablesLoss

Antenna

Gain Path Loss

Car LossBody

Loss Mobile

Sensitivity

Pout

Antenna

Gain


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VI. Practical Limitation

a. Hopping - is a form of CDMA where a digitalcode is used to continually change the frequency

of the carrier.

b. Losses - this are the energy released within asystem which must be given due attention when

making a design to achieve the objective being

set.

c. Size - this must be considered when there is a

limitation in the space for the equipment


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d. Cost - good engineering is maximum performance

with minimum cost

e. O&M - maintenance of certain equipment must be

given utmost attention because this makes the

system perform well in the long run.

f. Reliability - a good design must have a reliability

of 99.99% to avoid any failure of service whenever

there is a breakdown of equipment and this can bemaintained by employing diversity techniques.

RF Basic - Components and devices.ppt

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Transcript of RF Basic - Components and devices.ppt