Antennas Technology in Wireless Systems

Antennas Technology in Wireless Systems

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Description: Discussion topics include six wireless communication systems, cellular network architecture, why digital, components of a single path, multiple access and users, FDMA, TDMA, CDMA, trends in wireless communications, internet evolution and bandwidth, enabling entirely new wireless product segments, 3G terminal driven by price and function, and a brief history of wireless communications. .

 
Author: Yi-Cheng Lin (Fellow) | Visits: 2116 | Page Views: 2211
Domain:  High Tech Category: Mobile 
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Contents:
Chapter 1 Introduction of d f Antennas in Wireless Systems

Yi-Cheng Lin 2010 (c)

1

A Brief O f Overview of Wireless f l Communication Systems

Yi-Cheng Lin 2010 (c)

2

Yi-Cheng Lin 2010 (c)

3

Cellular Network Architecture

Yi-Cheng Lin 2010 (c)

4

Why Digital ? y g


Error/Interference improved Computation Power (CPU) increased DSP algorithms improved. l ith i d CODE Channel (CDMA) efficient and feasible Trends of SOC (system-on-chip)


all digital ? (software radio, H speed A/D) radio H-speed cost reduction size reduction antenna will be the key element in the future
Yi-Cheng Lin 2010 (c) 5

Components and Signal Path

Yi-Cheng Lin 2010 (c)

6

Multiple Access (Users) p ( )

Yi-Cheng Lin 2010 (c)

7

FDMA

Yi-Cheng Lin 2010 (c)

8

TDMA

Yi-Cheng Lin 2010 (c)

9

CDMA

Yi-Cheng Lin 2010 (c)

10

Trends in Wireless Communications



Voice Data Images g Internet Speed -- wired or wireless ? Wide bandwidth for speed/capacity demand GPS/E911 Applications (software)

Yi-Cheng Lin 2010 (c)

11

Internet Evolution: Bandwidth

Bandwidth (bps) 100,000,000 10,000,000 1,000,000 100,000
9.6k 9 6k 9M ADSL 3M Cable 2.4M CDMA2000 1xEV 306k 150k 64k 14.4k 14 4k

Fixed Internet
28.8k

128k 56k 9.6k

Wireless Internet

10,000
1200

2400 300

1,000 100 1970

1975

1980

1985

1990

1995

2000

2005

Yi-Cheng Lin 2010 (c)

12

How Fast is Wireless ?

Yi-Cheng Lin 2010 (c)

13

Enabling Entirely New Wireless Product Segments... Segments

MSM6000
- Sunglasses - Voice Command

MSM6050
- Kid Track - Basic Positioning

MSM6100
- Integrated Navigation - Positioning w/ Maps

MSM6500
- Game Pad - Networked Games

Yi-Cheng Lin 2010 (c)

14

3G Terminal Driven By Price and Function
Price Tier

1X

1X/WCDMA

1xEV-DO

High Navigation Device PDA Phone Telemetry Video conferencing

Voice Device

Mid Tier Location Tracker

Karaoke Phone

Music Phone

Game Phone

Video Phone

1xEV-DO

Entry Level

Voice Only

Voice + SMS

Browser Phone

Smart Phone

Meter

Data Usage
Yi-Cheng Lin 2010 (c)

15

Yi-Cheng Lin 2010 (c)

16

History of Wireless Communications


1862 1873 1888 1897 1924 1945 1957 1969 1979 1988 1983 1985 1991 1991 1993 1995 1998 2002

Michael Faraday discover the electo-magnetic reciprocal phenomenon electo magnetic Maxwell predicts the existence of electromagnetic waves Hertz demonstrates radio waves Marconi demonstrates mobile wireless communication to ships US police first use mobile communications Arthur C. Clarke proposes geostationary communication satellites Soviet Union launches Sputnik 1 communication satellite Bell Laboratories in the US invent the cellular concept NTT cellular system (Japan) JTACS cellular system (Japan) AMPS cellular frequencies allocated (US) TACS ( (Europe) ) USDC (US) GSM cellular system deployed (Europe) DECT & DCS (Europe) IS95 CDMA (US) Iridium global satellite system launched IMT-2000 third-generation cellular mobile systems deployed
17

Yi-Cheng Lin 2010 (c)

Who's who in EM History

Yi-Cheng Lin 2010 (c)

18

History y
... and God said

B B E t D H J t D B 0
... and there was light.
Yi-Cheng Lin 2010 (c) 19

Genesis
1:1 In the beginning God created the heaven and the earth. 1:2 And the earth was without form, and void; and darkness was upon the face of form the deep. And the Spirit of God moved upon the face of the waters. 1:3 And God said, Let there be light: and there was light. 1:4 And God saw the light, that it was good: and God divided the light from the light darkness. 1:5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day. ... ------- Bible Genesis 1:1-5 1:1 1:2 1:4 1:5

1:3 ... ----- 1:1-5
Yi-Cheng Lin 2010 (c) 20

Introduction to Propagation

Yi-Cheng Lin 2010 (c)

21

Yi-Cheng Lin 2010 (c)

22

Yi-Cheng Lin 2010 (c)

23

Introduction to Antennas


History of Antenna Development EM Spectrum EM Principle for Antennas Antenna's Role in Wireless Communications

Yi-Cheng Lin 2010 (c)

24

Antenna History - 1886 y


Heinrich Hertz

Yi-Cheng Lin 2010 (c)

25

Antenna History - 1905 y


G. G Marconi

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26

Antenna History - 1980 y


VLA

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27

Antenna History - 1985 y


Helical Antenna Array

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28

Antenna History - 2000 y


Mobile/Hand held Mobile/Hand-held Antennas

Yi-Cheng Lin 2010 (c)

29

Trends of Antenna Design in Modern Communications


Antenna Miniaturization


PIFA, WIFA, MLA, DRA, Chip Tapered Monopole, spiral,
WIFA for 3G handsets



Broadband Techniques




Multi-band Design


Fractal antennas Reconfigurable antennas 60 GHz UWB WLAN Antenna integrated in SOP

TGPS G1A



High F Hi h Frequency Antennas A t


MLA for PDA/GPS

Yi-Cheng Lin 2010 (c)

30

UMTS GSM Front-end Solutions - Example
Dual Antenna System for GSM/DCS/IMT
Ant

3

Duplexer 2110 - 2170 MHz 1920 - 1980 MHz

IMT2000 Rx +(100ohm) R +(100 h ) IMT2000 Tx

Ant

SP2T
Diplexer 1710 - 1880 MHz 880 - 960 MHz

DCS Rx+(50ohm) SAW Filter 1805 -1880 MHz LPF DCS Tx 1710 -1785 MHz SAW Filter EGSM Rx+(50ohm) EGSM Rx -(50ohm) EGSM Tx 880 - 915 MHz DCS Rx -(50ohm)

1

SP2T

925 -960 MHz 960 LPF

2
31

Yi-Cheng Lin 2010 (c)

Electromagnetic Spectrum g p

Yi-Cheng Lin 2010 (c)

32

Radio Frequencies Bands

Yi-Cheng Lin 2010 (c)

33

Antenna Fundamentals and System d l dS Parameters (Concepts)

Yi-Cheng Lin 2010 (c)

34

What is an Antenna ?

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35

Antenna Fundamentals (Concepts and Physical Meanings)




How does it work ? Near vs. Far fields Coordinate System (vector fields, polarization, patterns) Terminology of Antenna Patterns Directivity vs. Gain Efficiency

Yi-Cheng Lin 2010 (c)

36

EM Principles for Antennas p


Maxwell s Maxwell's Equations Radiation Mechanism (accelerated charges) Microwave/RF Ci it (drive) Mi /RF Circuitry (d i ) Radiator (the interface) ( )


Size Frequency Shape Patterns Composition Gain/Loss

Yi-Cheng Lin 2010 (c)

37

Maxwell's Equations q
B E t
H

D J t

D v
B 0
Yi-Cheng Lin 2010 (c) 38

Considerations for Radiation
�DC Current static magnetic field ( ) �Accelerated electrons radiation (EM waves)

Yi-Cheng Lin 2010 (c)

39

Generation of EM Waves
> Compared to sound/water waves...
axis) in the space � Static E-Field prevail the entire space with g p light speed � Field continuity max perturbation in the transverse direction (x-y plane), none in z axis � Oscillation continuous spherical waves � Perturbed Er near fields (reactive) � Perturbed Et propagated waves � Time Harmonic Ez Ht Coupled E-H fields ElectroMagnetic Waves
� Charge Oscillating between A & B (along z

> Comparison between static fields and wave fields...
Yi-Cheng Lin 2010 (c)

40

Coordinate Systems y
Vector Fields in Rectangular and Spherical coordinates Right Handed

E ( Ex , E y , Ez )
E ( Er , E , E )

^ ^ ^ x y z ^ ^ ^ r

Yi-Cheng Lin 2010 (c)

41

Field Regions g
Due to the finite antenna size...

Yi-Cheng Lin 2010 (c)

42

Antenna Radiation Pattern
Directional
� Spherical Coordinate ( r, , ) � Factor out the distance decay (field/power) 1 r � Here, "r" represents "Gain/Directivity" � G and D in dBi unit (relative to "I"sotropic ant.) � M i Lobe/Beam Main L b /B � Nulls - HPBW: Half-Power Beam Width - FNBW: First Null Beam Width � Side Lobes SLL (dB) � Back Lobe Front-to-back Ratio (dB) � Polarization defined on E-field vector �Not shown in the pattern �In practice, Gand Gcan be measured
2

Yi-Cheng Lin 2010 (c)

43

Omni directional Omni-directional Radiation Pattern
� Hertzian Dipole for example p p � Isotropic vs. Omni-directional

Yi-Cheng Lin 2010 (c)

44

Directivity y
There are two ways to express the antenna directivity.
Function:

Scalar:

dBi vs. dBd : relative to "isotropic" or "dipole" antenna (0 dBd = 2.15 dBi) vs isotropic dipole 2 15
Yi-Cheng Lin 2010 (c) 45

Polarization
�Linear Pol. �Circular Pol. �Elliptical Pol. �Left/Right Hand Pol. IEEE Definition �Thumb � Propagation �Other fingers � E-field variation at a fixed transverse plane �Axial Ratio (AR)
AR OA(long ) 1 OB ( short )

AR (dB ) 20 log( AR ) 0

Yi-Cheng Lin 2010 (c)

46

The equivalent circuit model of antenna �
Radiation Resistance and Antenna Efficiency

Equivalent Circuits: q

Radiation Resistance Rr:

Pr I 2 Rr

Efficiency e:


Yi-Cheng Lin 2010 (c)

Pr Pt
47

Transmitting Antenna g

� Antenna Gain:

G eD

� Effective Isotropic Radiated Power (EIRP): (dBm, dBW)

EIRP Pt ( dB ) G dBi
� Effective Radiated Power (ERP):

ERP Pt ( dB ) G dB d EIRP 2 .15 ( dB )
48

Yi-Cheng Lin 2010 (c)

Receiving Antenna g


Effective Antenna Aperture/Area Pr 2 Ae G Si 4 Receiving Sensitivity


Ae



Detectable minimum received power For example -105dBm for 3G Handsets example, 105dBm

( Pr ) min



Antenna Noise Temperature p TB ( , )G( , )d
TA

TA

Where TB is the background brightness temperature Yi-Cheng Lin 2010 (c) 49

G( , )d

Antenna Sub-System y
�Antenna Impedance: p � Return Loss:

Z A (look into the antenna) ( )

S11 ( dB ) 20 log
VSWR 1 1

� Voltage Standing Wave Ratio:

� Bandwidth: characterization of frequency response �R.L. �Gain �AR
f
Yi-Cheng Lin 2010 (c) 50

Return Loss

0 -5 5 -10

dB

-15 -20 -25 -30 58 59 60 61 62 63 64

GHz

Yi-Cheng Lin 2010 (c)

51

Gain & Axial-ratio

12

10

8

dB

6

4

2

Axial-Ratio Gain G i

0 58 59 60 61 62 63 64

GHz

Yi-Cheng Lin 2010 (c)

52

Reciprocity

The b t T Th best Tx antenna i also t is l the best Rx antenna. Antenna Gain Patterns valid for both Tx and Rx Tx and Rx antennas must have the same polarization for max reception of the link.

Yi-Cheng Lin 2010 (c)

53

RF/Antenna System Parameters


RF System in Wireless Communications Noise Issues N i I System SNR y Path/Propagation Loss Link B d t Li k Budgets

Yi-Cheng Lin 2010 (c)

54

Defining RF Systems g y

RF System

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55

Divisions of RF Systems y


RF Circuitry Antenna S b A t Sub-system t Propagation (Channel Modeling) p g ( g) Link budgets (SNR, SINR, BER, FER, Capacity...) Capacity )

Yi-Cheng Lin 2010 (c)

56

Free Space Loss p
4R LF Pr EIRP LF GR dB dBi
2

�In decibels:

LF 32.44 20 log Rkm 20 log F MHz
Yi-Cheng Lin 2010 (c) 57

Noise


Noise Power
Pn kT n B

G, F, B

Signal-to-Noise Ratio (SNR)


SNR =

Ps Pn



A noisy two-port network (G F B) i t t t k (G,F,B)


Gain = Pso / Psi Noise Factor, F SNR i / SNR o 1 Noise Figure NF(dB)=10*log(F)>0 dB Figure, NF(dB)=10 log(F)>0
Yi-Cheng Lin 2010 (c) 58

Link Budgets g

1 2 Pr Pt G t G r ( PLF ) 4 R 2 4
^ ^ PLF p t p r
2

Yi-Cheng Lin 2010 (c)

59

Cascaded Noise and Gain

Total G,F

Front end dominates !

Yi-Cheng Lin 2010 (c)

60

Example of Link Budgets p g
Terrestrial Mobile Communications

Yi-Cheng Lin 2010 (c)

61

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