Lecture on pifa a ntenna1

Presented By :
Akhilesh Verma
NITTTR, Chandigarh

Outline
 Introduction
o What is antenna
o How antennas work
o Need of antenna
o Use of antenna
o Parameters of antenna
 Types of antenna use in mobile phone
o External antenna
o Internal antenna
 Antennas use in different cell phones
 Handset Design Evolution
1 June 2014
National Institute of Technical Teacher's Training & Research, Chandigarh
2

What is an antenna
 An Antenna is a device used to transform an RF signal, travelling on a
conductor into an EM wave in free space or vice versa.
or
o An antenna is a transducer between a guided wave and a radiated wave, or
vice versa.
 The structure that “guides” the energy to the antenna is most evident as a
coaxial cable attached to the antenna. The radiated energy is characterized
by the antenna’s radiation pattern.
1 June 2014
3

Continued…
 Antennas demonstrate a property known as reciprocity , which means that
an antenna will maintain the same characteristic regardless if it is
transmitting or receiving.
 Antennas can be broadcast or receive only.
 A special license is needed to broadcast but not to receive.
1 June 2014
4

How antennas work?
 First of all to work properly the antenna system must be matched to the
transmitter.
 All modern transmitter have an output impedance of 50Ω.
 There are several ways to match them:
o Pruning the length of the antenna
o Using an antenna tuner
o Matching the antenna with the length of transmission line called a
matching section.
 To understand the working of antenna, firstly you have to understand
electromagnetism.
1 June 2014
5

Continued…
 If two poles of direct current(DC) voltage source to the two ends of a
coil of wire, current will flow through the coil of wire and it will
become magnetized. The magnetized coil is known as electromagnet.
 If voltage and current can cause a coil to become magnetized, the
reverse is true i.e a magnetic field can produce a voltage and a current
in a coil, this is known as faradays principle of magnetic induction.
 A voltage will produced at the ends of the coil of wire as we move any
permanent magnet close to and parallel to the coil.
 Move the magnet in one direction, and current will flow in one
direction, reverse the direction the magnet is moving and the current
will flow in the opposite direction.
1 June 2014 National Institute of Technical Teacher's Training & Research, Chandigarh
6

Continued…
 Moving the magnet back and forth produces alternating current.
 Any moving magnetic field can induce current in another coil, if that
moving magnetic field passes through a second nearby coil, it will induce an
alternating current in the second coil.
 A straight wire that has an AC current flowing through it also has a
magnetic field surrounding it. The magnetic field from the wire radiate out
into and become weaker with distance.
 The radiating magnetic field from a wire is known as “electromagnetic
radiation”, the wire that radiates becomes the transmitting antenna.
 Some distance away, a second wire in the path of these waves has current
induced into it by the passing electromagnetic waves. This second wire will
be the receiving antenna.
7

Need of antenna
 For transmission
 For reception
8

Uses of antennas
 Antennas are used for:
o Radio
o TV
o Satellite
o Cellular
o Wifi
o Radar
o Space communications
9

Parameters of antenna
1. Input impedance
2. Return loss
3. Bandwidth
4. Directivity
5. Gain
6. Radiation pattern
7. Beamwidth
8. Side lobes
9. Nulls
10. Polarization
10

Continued…
1. Input impedance
o For an efficient transfer of energy, the impedance of the radio, of the
antenna and of the transmission cable connecting them must be the same.
o Transceivers and their transmission lines are typically designed for 50Ω
impedance.
o If the antenna has an impedance different from 50Ω, then
there is a mismatch and an impedance matching circuit is required.
2. Return loss
o The return loss is another way of expressing mismatch.
o It is a logarithmic ratio measured in dB that compares the power reflected
by the antenna the power that is fed into the antenna from the transmission
line.
11

Continued…

12

Continued…
4. Directivity
o Directivity is the ability of an antenna to focus energy in a particular
direction when transmitting, or to receive energy better from a particular
direction when receiving.
o In a static situation, it is possible to use the antenna directivity to
concentrate the radiation beam in the wanted direction.
o In a dynamic system where the transceiver is not fixed, the antenna should
radiate equally in all directions, and this is known as an omni-directional
antenna.
5. Gain
o The gain of an antenna (in any given direction) is defined as the ratio of
the power gain in a given direction to the power gain of a reference
antenna in the same direction.
13

Continued…
o isotropic radiator as the reference antenna in this definition.
o isotropic radiator would be lossless and that it would radiate its energy
equally in all directions.
o An antenna gain of 3 dB compared to an isotropic antenna would be
written as 3 dBi.
6. Radiation pattern
o The radiation or antenna pattern describes the relative strength of the
radiated field in various directions from the antenna, at a constant
distance.
14

Continued…
15

Continued…
Dipole Antenna 3D radiation pattern Omni-Directional 3D pattern
16

Continued…
7. Beamwidth
o The angular distance between the half power points is defined as the
beamwidth.
o Half the power expressed in decibels is —3dB, so the half power
beamwidth is sometimes referred to as the 3dB.
17

Continued…
8. Side lobes
o No antenna is able to radiate all the energy in one preferred direction.
Some is inevitably radiated in other directions. The peaks are referred to as
side lobes, commonly specified in dB down from the main lobe.
18

Continued…
9. Nulls
o In an antenna radiation pattern, a null is a zone in which the effective
radiated power is at a minimum.
o A null often has a narrow directivity angle compared to that of the main
beam.
10. Polarization
o Polarization is defined as the orientation of the electric field of an
electromagnetic wave.
o Polarization is in general described by an ellipse.
o Two special cases of elliptical polarization are linear polarization
and circular polarization.
19

Continued…
o With linear polarization the electric field vector stays in the same plane
all the time.
o Vertically polarized radiation is somewhat less affected by
reflections over the transmission path.
o Omnidirectional antennas always have vertical polarization.
o With horizontal polarization, such reflections cause variations in received
signal strength.
o In circular polarization the electric field vector appears to be rotating
with circular motion about the direction of propagation, making one
full turn for each RF cycle.
20

Continued…
21

Antennas for Mobile devices
• The type of antenna that is used with a particular type of phone is normally
determined by dimensional considerations and speciﬁc absorption rate (SAR)
regulations.
• SAR(specific absorption rate) is a measurement of how much electromagnetic radiation
is absorbed by body tissue while using a mobile phone. Higher the SAR more radiation
will absorbed.
• In the United States, the Cellular Telecommunications and Internet Association
(CTIA) requires all cell phones to comply with the Federal Communications
Commission (FCC) SAR limit of 1.6 W/kg in 1g of tissue.
22

Data Sheet of SAR Values for Diff.
Mobile Phones
http://www.s21.com/sar.htm
23
Manufacturer Model SAR
(W/Kg)
Apple iPhone 3G S 1.19
Apple iPhone 5 1.25
BlackBerry Curve 8900 1.01
BlackBerry Curve 9320 1.56
Samsung Chat S3350 0.817
Samsung Galaxy Nexus 0.456
Motorola A830 0.69
Motorola Z3 1.02
Nokia 2100 0.55
Nokia N97 0.66
Sony Xperia Z Ultra 0.339

Bad Effect of Cellphone on Health
 Impaired Concentration
o Excess use of mobile phones reduces your ability to focus.
o You take more time to do a task whether it’s solving
mathematical question or approaching the car breaks to avoid
an accident.
 General Sickness
o The moment you touch the mobile screen , 20% to 30% of all
Virus and bacteria were transmitted to your hands and finally
into your body.
24

 Eye problems
o The combination of holding your phone too close to your
Eyes along with staring at its viciously small font can lead
to eye strain, headaches, dry eye and blurred vision.
 Risk to Unborn
o Use of Cellphones during pregnancy slows down the rate of
brain development of the fetus or may lead to hyper activity.
25

 Neurodegenerative Disorders
o The harmful radiations emitted by the cell phones can
damage DNA
o DNA damage in brain cells can affect neurological functions
o This can possibly lead to neurodegenerative diseases
 Heart risks
o Radiations from cordless phones (including mobile phones)
can cause irregularities in normal functioning of heart
26

 Loss of Hearing
o The radiation emitted by cell phones can damage delicate workings
of the inner ear
o People who are subjected to long-term mobile phone use are
at a higher risk of developing hearing loss
 Brain Cancer
o Cell phone radiation may be slowly damaging your brain
o radio frequency field generated by your cell phone triggers heating
up of brain tissue
27

How to reduce your exposure to
phone radiation
o Do not use your phone more than necessary and keep your calls short.
o Send a text instead of making a call.
o Try to avoid using your phone if the signal strength is low - find a better location to
make a call.
o Try to use the phone outdoors rather than inside, or move close to a window to
make a call.
o Keep the phone (and particularly the aerial) as far as possible from your head.
o Switch off your phone when not in use.
28

Antennas for Mobile devices
Following are main types of antennas used in cellular phones:
 External Antennas
• Monopoles
• Helical
29

Continued…
Following are main types of antennas used in cellular phones:
 Internal Antennas
 Microstrip antennas(MSA)
 Planar inverted F antennas(PIFA)
 Menader line antennas(MLA)
30

Planar inverted F antenna
 The inverted F Antenna (IFA) typically consists of a rectangular planar element located
above a ground plane, a short circuiting plate or pin, and a feeding mechanism for the
planar element.
 The inverted F antenna is a variant of the monopole where the top section has been
folded down so as to be parallel with the ground plane.
 This is done to reduce the height of the antenna, while maintaining a resonant training
length.
 PIFA can be considered as a kind of linear inverted F antenna (IFA) with the wire
radiator element replaced by a plate to expand the bandwidth.
31

Continued…
 Advantages of PIFAAntenna
o It can be hiding into the housing of the mobile while comparable to whip/rod/helix
antennas.
o It reduces the backward radiation toward the user’s head, minimizing specific absorption
rate (SAR).
 Disadvantage of PIFAAntenna
o Narrow bandwidth characteristic of PIFA is one of the limitations for its commercial
application for wireless mobile.
32

Antennas use in different cell phones
33
Model Antenna Frequency bands
Apple iPhone 2G Planar Monopole GSM850/900/1800/1900
Apple iPhone 3G Planar Monopole GSM850/900/1800/1900
+3G
Blackberry 8100 Planar Monopole GSM850/900/1800/1900
Motorola E398 PIFA GSM900/1800/1900
Motorola L2000/P7389 Helix GSM900/1800/1900
Motorola W208 PIFA GSM900/1800
Nokia 2626 PIFA GSM900/1800
Sony Ericsson K660i PIFA GSM850/900/1800/1900
+3G
Nokia 5300 Planar Monopole GSM900/1800/1900
Samsung Helix GSM900/1800

Handset Design Evolution
34

1 June 2014 Cell Phone Antennas 35
The first
DynaTAC
phone
weighted
around 2.2 Kgs
(approx.)
The battery
life would
last for only
20 minutes
Nicknamed
the
‘The BRICK’
Its cost was
around
4,000 US
Dollars
Quick Facts About the First Cell
Phone

How the handset antennas get evolved in the past 20 years?
36

1G(Analog) in 1980s-800 MHz
37

2G(Digital) in 1990s-GSM900 MHz
And 1800 MHz
 New services came-text messaging, multimedia, internet access ,etc operated at GSM 900
MHz, later introduced at 1800 MHz
38

Continued…
39

Dual Band Internal Antenna
40

Single Band PIFA
41

First Dual Band PIFA
42

First 2G Mobile with Fully Internal
Antenna
43

44

First Triple Band PIFA
45

Handset Antennas in 2000s-3G0
46

Location of antennas in different
mobile phones
47

Continued…
48

6/1/2014 Intrusion Detection Systems 49

Lecture on pifa a ntenna1

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