This document discusses electromagnetic radiation (EMR) and electromagnetic shielding materials (EMS). It defines EMR and its classification. It describes the sources and hazards of EMR. Parameters that affect EMR shielding effectiveness are discussed. Various EMS materials like conductive fabrics and their production techniques are explained. Standards for measuring EMS effectiveness are summarized. The increasing use of electronics and need to reduce EMR hazards is noted.
Optical detectors, as the name implied, can detect the amount of light received. It is a device that converts light signals into electrical signals, which can then be amplified and processed.
4 radio wave propagation over the earthSolo Hermelin
Describes the Electromagnetic Wave Propagation over the Earth Surface. Please send comments to solo.hermelin@gmail.com.
For more presentations on different subjects pleade visit my website at http://www,solohermelin.com.
This presentation is in the Radar folder.
A communication system is for transmitting and receiving the information that users want to exchange. To make up a communication system, we can adopt the FDMA, TDMA, CDMA, and so on. In this presentation, we introduce a simplified communication blocks with which we can understand a modern system.
Optical detectors, as the name implied, can detect the amount of light received. It is a device that converts light signals into electrical signals, which can then be amplified and processed.
4 radio wave propagation over the earthSolo Hermelin
Describes the Electromagnetic Wave Propagation over the Earth Surface. Please send comments to solo.hermelin@gmail.com.
For more presentations on different subjects pleade visit my website at http://www,solohermelin.com.
This presentation is in the Radar folder.
A communication system is for transmitting and receiving the information that users want to exchange. To make up a communication system, we can adopt the FDMA, TDMA, CDMA, and so on. In this presentation, we introduce a simplified communication blocks with which we can understand a modern system.
Any training class is a considerable investment in terms of cost and your time. You can’t afford to waste any of your precious time and you need to attend something that is useful and improves your productivity. After five years of presentation throughout the world, this workshop is well polished, practical and relevant.
The aim of this workshop is to help you identify, design, prevent and fix common EMI/EMC problems with a focus on earthing and shielding techniques. Learning how to fix earthing and shielding problems on the job can be very expensive and frustrating. Although it must be noted that most of the principles involved are simple, this workshop will give you the tools to approach earthing and shielding issues in a logical and systematic way.
This workshop focuses on the issues of interest to you if you are working in design, operation or maintenance of analog or digital systems involving sensors, data acquisition, process control, cables, signal processing, programmable logic controllers, power distribution, high speed logic etc.
The circuit board layout section concentrates on design and layout of circuits and components on a printed circuit board. The overall focus is on useful design and systems issues; not about regulations and standards. The idea is that you will take this material back with you to your work and apply the key principles immediately to your design and troubleshooting challenges.
WHO SHOULD ATTEND?
Building service designers
CAD managers
Consulting engineers
Data systems planners and managers
Design engineers
Electrical and instrumentation technicians
Electrical contractors
Electrical engineers
Electrical inspectors
Electricians
EMC specialists
Electronics and systems engineers and technicians
Instrumentation and control engineers
Logic designers
Maintenance engineers
Mechanical engineers
Power system protection and control engineers
Printed circuit board designers
Project engineers
Safety professionals
Signal integrity specialists
Technical managers
Test engineers
MORE INFORMATION: http://www.idc-online.com/content/practical-shielding-emcemi-noise-reduction-earthing-and-circuit-board-layout-66
The attached narrated power point presentation attempts to explain the working principle, types, classifications, merits, demerits, applications,safety and deployment issues related to Raman Amplifiers. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
Radiation pattern of a cell tower antennaNeha Kumar
Radiation Pattern from the cell tower Antenna has been drawn for basic understanding of a radiation pattern.
Page1:
This diagram was mainly used to describe why on a certain building the radiation levels vary from one apartment(say 7th floor) to the apartment above or below (6th and 8th floor) in a building at Khar (West), Mumbai.
The radiation pattern of a cell tower antenna is defined by its lobes. Radiation will be highest from the primary lobes in the horizontal direction. There is also radiation from secondary lobes.As seen in the figure, the readings that will be taken in between the lobes will be much lesser.
As seen the figure, the radiation will also be high vertically downward from the secondary lobes. This is what most mobile operaters hide or are not aware of in India.
Page 2:
Distance is another critical factor. The power density varies by (1/R2), where is R is the distance. People living within 50-300meter radiaus are in the high radiation zone. This data has been taken from a another country outside India. In the US for example, residential areas generally have amplifiers of 1-2 W. However in India, in many places even 100 to 200W of amplifiers are used and their are clusters of antennas from multiple operators on the roof top of several residential and office premises.
Page 3:
Simulated radiation pattern of a cell tower antenna from Prof. Girish kumar, IIT Bombay.
Page 4:
USHA KIRAN BUILDING - several cancer cases
Through the help of the above typical radiation pattern, let’s analyze the news reported in Mid-day, Mumbai dated Jan. 3, 2010, which stated - “Mumbai's swanky Usha Kiran building says the four cancer cases there could be linked to mobile towers installed on the facing Vijay Apartments”. The picture taken from the Usha Kiran building of the several antennas installed on the seventh floor of Vijay Apartments is shown in Fig. pn Page 4. People living in the 6th, 7th and 8th floor in the opposite building will get maximum radiation as they are in the main beam direction. People living on the other floors will receive lesser radiation as beam maxima is reduced considerably as can be observed from vertical radiation pattern. In the horizontal direction again, people living in the front side of the antenna will receive much higher radiation compared to people living in the back side of antenna.
http://www.mid-day.com/news/2010/jan...
Recently (as on Jan 2011) two more cancer cases have been reported on the 5th and on the 10th floor.
hello readers i give my PPT presentation for about antenna and ther properties and working explain in this ppt
i hope you like it THANK YOU.......!!!!!!!
Any training class is a considerable investment in terms of cost and your time. You can’t afford to waste any of your precious time and you need to attend something that is useful and improves your productivity. After five years of presentation throughout the world, this workshop is well polished, practical and relevant.
The aim of this workshop is to help you identify, design, prevent and fix common EMI/EMC problems with a focus on earthing and shielding techniques. Learning how to fix earthing and shielding problems on the job can be very expensive and frustrating. Although it must be noted that most of the principles involved are simple, this workshop will give you the tools to approach earthing and shielding issues in a logical and systematic way.
This workshop focuses on the issues of interest to you if you are working in design, operation or maintenance of analog or digital systems involving sensors, data acquisition, process control, cables, signal processing, programmable logic controllers, power distribution, high speed logic etc.
The circuit board layout section concentrates on design and layout of circuits and components on a printed circuit board. The overall focus is on useful design and systems issues; not about regulations and standards. The idea is that you will take this material back with you to your work and apply the key principles immediately to your design and troubleshooting challenges.
WHO SHOULD ATTEND?
Building service designers
CAD managers
Consulting engineers
Data systems planners and managers
Design engineers
Electrical and instrumentation technicians
Electrical contractors
Electrical engineers
Electrical inspectors
Electricians
EMC specialists
Electronics and systems engineers and technicians
Instrumentation and control engineers
Logic designers
Maintenance engineers
Mechanical engineers
Power system protection and control engineers
Printed circuit board designers
Project engineers
Safety professionals
Signal integrity specialists
Technical managers
Test engineers
MORE INFORMATION: http://www.idc-online.com/content/practical-shielding-emcemi-noise-reduction-earthing-and-circuit-board-layout-66
The attached narrated power point presentation attempts to explain the working principle, types, classifications, merits, demerits, applications,safety and deployment issues related to Raman Amplifiers. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
Radiation pattern of a cell tower antennaNeha Kumar
Radiation Pattern from the cell tower Antenna has been drawn for basic understanding of a radiation pattern.
Page1:
This diagram was mainly used to describe why on a certain building the radiation levels vary from one apartment(say 7th floor) to the apartment above or below (6th and 8th floor) in a building at Khar (West), Mumbai.
The radiation pattern of a cell tower antenna is defined by its lobes. Radiation will be highest from the primary lobes in the horizontal direction. There is also radiation from secondary lobes.As seen in the figure, the readings that will be taken in between the lobes will be much lesser.
As seen the figure, the radiation will also be high vertically downward from the secondary lobes. This is what most mobile operaters hide or are not aware of in India.
Page 2:
Distance is another critical factor. The power density varies by (1/R2), where is R is the distance. People living within 50-300meter radiaus are in the high radiation zone. This data has been taken from a another country outside India. In the US for example, residential areas generally have amplifiers of 1-2 W. However in India, in many places even 100 to 200W of amplifiers are used and their are clusters of antennas from multiple operators on the roof top of several residential and office premises.
Page 3:
Simulated radiation pattern of a cell tower antenna from Prof. Girish kumar, IIT Bombay.
Page 4:
USHA KIRAN BUILDING - several cancer cases
Through the help of the above typical radiation pattern, let’s analyze the news reported in Mid-day, Mumbai dated Jan. 3, 2010, which stated - “Mumbai's swanky Usha Kiran building says the four cancer cases there could be linked to mobile towers installed on the facing Vijay Apartments”. The picture taken from the Usha Kiran building of the several antennas installed on the seventh floor of Vijay Apartments is shown in Fig. pn Page 4. People living in the 6th, 7th and 8th floor in the opposite building will get maximum radiation as they are in the main beam direction. People living on the other floors will receive lesser radiation as beam maxima is reduced considerably as can be observed from vertical radiation pattern. In the horizontal direction again, people living in the front side of the antenna will receive much higher radiation compared to people living in the back side of antenna.
http://www.mid-day.com/news/2010/jan...
Recently (as on Jan 2011) two more cancer cases have been reported on the 5th and on the 10th floor.
hello readers i give my PPT presentation for about antenna and ther properties and working explain in this ppt
i hope you like it THANK YOU.......!!!!!!!
Electromagnetic Interference and Electromagnetic Compatibility (EMI/EMCAishwary Singh
• Characterizing the threat
• Setting standards for emission and susceptibility levels
• Testing of Equipment on heavy Vibrations
• Testing for standards compliance
For queries,
Aishwarya
palsinghaishwarya@gmail.com
Introduction
Aspects of EMC
Definitions
Electrical Dimensions and Waves
EMC Requirements for Electronic Systems
Effects of EME/EM Interference
EMC Testing Routine
List of EME and EMI Tests
Avoid EMC Failure
EMC EMI testing standard :CISPR 16
EMI EMC standard for testing: IEC 61000
Typical EMC Test Facilities
Semi-Anechoic Chamber (10m) configuration
Limits and Test for Radiated Emission(RE) and Conducted Emission(CE)
Test for Radiated Susceptibility(RS), Conducted Susceptibility(CS) and Electrostatic Discharge(ESD)
The vast maturity of us are employed to the electronic comforts of current life. Yet, not numerous of us know about the conceivable good gambles with introduced by the contrivances that make our reality work.
Our electrical lines, cellphones, broilers, Wi- Fi switches, PCs, and different machines convey a swell of inappreciable energy swells. Electric and seductive fields( EMFs) are created anyplace power is employed, incorporating at home and in the working terrain.
A many specialists are upset about implicit good impacts from these fields. Yet, would it be judicious for us to be concerned?
Kinds of EMF openness
Radiation exists across what is known as the electromagnetic range. This radiation goes from exceptionally high- energy( called high- rush) toward one side of the range, to extremely low- energy( or low- rush) on the contrary end.
Cases of high- energy radiation include
•x-beams
• gamma beams
• some advanced- energy bright( UV) beams
A LITERATURE SURVEY ON ELECTROMAGNETIC SHIELDINGIJEEE
EMI (electromagnetic interference) is the disruption of operation of an electronic device when it is in the vicinity of an electromagnetic field (EM field) in the radio frequency (RF) spectrum that is caused by another electronic device. It is a disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. Here we study about the shielding theory so as to reduce the effects of EMI.
Fundamentals of electromagnetic compatibility (EMC)Bruno De Wachter
Electromagnetic interference, EMI, has become very important in the last few decades as the amount of electronic equipment in use has increased enormously. This has led to an increase in the sources of interference, e.g. digital equipment and switching power supplies, and an increase in the sensitivity of equipment to interference, due to higher data rates.
This development demands high quality electrical installations in all buildings where electromagnetic non-compatibility leads to either higher costs or to an unacceptable decrease in safety standards.
This application note gives an overview and a basic understanding of the major physical principles of electromagnetic interference and an introduction to the principles of mitigation of disturbing effects. As a result, the measures required to achieve an EMC-compliant installation should be easily understood.
"Mobile phones are an important part of daily life; thus, the rate of usage of mobile phones is increasing on a daily basis. Because they work in connection with base stations, number of base stations has to be boosted as long as the trend in the use of them continues. Because each base station runs by radiating electromagnetic waves, this is consideration source of distribution for many people from a medical point of view.
In this work we explained the radiofrequency and microwave radiation out from some mobile telephones towers studies and Measurements were done in many countries in the world in Sudan capital Khartoum , Malaysia, Gaza and Turkish capital Ankara.
"
2. Radiation : The process by which unstable nuclei of
atom emit a quantity of energy, or a particle. This emitted
particle or energy is known as radiation.
Classification of radiations:
1. Particle radiation (tiny and fast moving material having
both energy and weight)
2. Electro magnetic radiation (pure energy )
2
3. Electromagnetic radiation (EM radiation or EMR) is a form of energy
emitted by charged particles, which exhibits wave-like behavior as it
travels through space.
EMR has both electric and magnetic field components, which stand
in a fixed ratio of intensity to each other, and which oscillate in phase
perpendicular to each other and perpendicular to the direction of
energy and wave propagation.
3
5. 1. Electromagnetic waves are propagated by oscillating electric
and magnetic fields oscillating at right angles to each other.
2. Electromagnetic waves travel with a constant velocity of 3 x
108 ms-1 in vacuum.
3. Electromagnetic waves are not deflected by electric or
magnetic field
4. Electromagnetic waves can show interference or diffraction.
5. Electromagnetic waves are transverse waves.
6. Electromagnetic waves may be polarized.
5
6. Natural sources Man made sources
cosmic exposure at public places
terrestrial occupational exposure
internal
6
7. Broadcast antennas Cell towers
Digital TV signals Doppler weather radar
Electric trains Over telephone wires
Microwave beacons Pagers
Power lines Radio transmitters
Satellite radiation Wi-Fi antennas
Wiring in airplanes Digital display
Cell phone chargers Cell phones
Compact fluorescent light (CFL) Computers
Cordless phones
7
10. Electrical hazards : Strong radiation can induced current capable
of delivering an electric shock to persons and animals. It can also
overload and destroy electrical equipment.
Fire hazards : EMR can cause electric currents strong enough to
create sparks and can ignite flammable material and gases , leading
to an explosion.
Biological hazards : EM field can cause dielectric heating ex.
Touching and antenna can cause severe burns.
10
11. EMR can cause cancer , high blood pressure , brain tumors ,
headache, leukemia, brain damage etc.
WHO facts says that EMR can cause depression , cardiovascular
disorder, reproductive function, developmental disorders,
immunological modification etc. but these have lesser chances
than for child hood leukemia.
Electromagnetic interference : it is an unwanted disturbance
that effect the electrical circuit due to EMR emitted from an
external source .
It May interrupt , obstruct or limit the effective performance of
the circuit.
11
12. Energy of the incident radiation
Depth of penetration
Source of emission
Duration of exposure
Frequency of EMR waves
Type of EMR waves
Distance from the object
12
13. It is a process by which a material is able to reduce the
transmission of EMR that effects the humans or equipments.
EMS material are used to exclude the unwanted EMR or signals. It
also provide protection against the EM pulses which can disrupt
neighbouring computers .
It provides protection by reducing signals to level at which they no
longer effect equipment or can no longer be received. This is
achieved by reflecting and absorbing the radiation.
13
14. The primary mechanism of EMI shielding is usually reflection.
For reflection of the radiation by the shield, the shield must have
mobile charge carriers (electrons or holes) which interact with the
electromagnetic fields in the radiation.
A secondary mechanism of EMI shielding is usually absorption. For
significant absorption of the radiation by the shield, the shield
should have electric and/or magnetic dipoles which interact with the
electromagnetic fields in the radiation.
Other than reflection and absorption, a mechanism of shielding is
multiple reflections, which refer to the reflections at various surfaces
or interfaces in the shield.
14
16. Electromagnetic shielding is used in,
Aerospace aviation: In protection of highly advanced avionic
equipments.
Anti-terrorism: Encryption of relevant secret codes related to
national security.
Communication: Safeguarding highly sensitive digital signal
processing and microwave operating band
Defense: To protect equipment related to military, navy or air force.
Information Technology: Protect users from radioactive effects of
computers and peripherals.
Medical: Prevents interference of electromagnetic waves given out
by medical devices especially during critical operations.
Transport: For improved performances of automomotive
electronics luxury devices, vehicle tracking system and detection
surveillance systems, electric cars etc. 16
17. 1. Conductive materials
2. Nano and micro-carbon black
3. Sub micro- and micro-powders of Al, Cu, Ni etc.
4. Stainless steel fibers
5. Silver-coated polyamide fibres
6. Plastic fibre such as poly phenylene vinylene , poly
Acetylene(doped form)
7. Cellulosic fibers.
17
18. Reflection /absorption / multi reflection of EM waves
It should be flexible & light weight.
Conductivity
Corrosion resistant
Durability
Low cost etc.
18
19. Material used for EMS include sheet metal mesh , metal form ,And
plasma .
Multi layer knitted fabric such as interlock structure
Textile Multi layer structure
Composite materials for shielding
Conductive fabric
Shielding foil tapes
EMI conductive adhesives
Mostly conductive fabric are used prepared with different
techniques.
19
20. Incorporation of conductive fibres or yarns in to the fabric
Lamination of conductive layer on to the surface of the fabric such
as conductive coating , spray ,ionic plating .
Addition to the conductive fillers such as conductive carbon black,
carbon fibre ,metal fibre (stainless steal AL, CU),metal powder and
flex to the insulating material
Grafting a conductive polymer such as poly anilines , poly pyrolle
, poly vinyl alchol,poly amide on to the fabric
Coating of individual fibre by conductive polymer
Few examples : Filosano fabric , Flectron , Phantom fabric, High
performance silver mesh fabric etc.
20
21. Shielding effectiveness:- It is the ratio of electromagnetic field
strength measured without (E0) & with (E1) the tested material
when it separates the field source and the receptor. It I s given by
SE = Eo /E1
Insertion loss (A) : It is a measure of losses in a transmission
signal cause by the tested material being inserted in to the
measuring channel . It is given by
A = Uo/ U1
Where Uo = channel out put voltage without tested material
U1 = output voltage with tested material
21
22. For woven fabric :
1. Effect of type of material: metals have significantly higher
EMS value compare to polymer or cellulosic material
Metal > cellulose > polyester (synthetic polymer)
2. Effect of no. of apertures : EMS value decreases with
increase in no. of holes . However for metals no significance
difference is there in shielding.
3. Effect of yarn count and thread density : with increase in
yarn count the effectiveness increases.
4. Effect of no. of fabric layers : the shielding of the material is
directly proportional to the thickness of the material.
22
23. 1. Effect of metal wire diameter: With increase in dia. the
shielding effectiveness decreases .
2. Effect of knitted structure : Interlock and rib structure have
more shielding effectiveness then the plain structure.
3. Effect of thickness: Thickness of the knitted fabric shows
negligible influence on EMS effectiveness at low to higher
frequency.
4. Effect of tightness factor : Fabric with higher tightness factor
have good shielding effectiveness then lower.
23
24. Mil –STD 285 :
1. Introduced in 1956
2. This standard has an upper frequency limit of 400 MHz
3. Developed for large-enclosure and shelter assessment.
IEEE-STD 299:
1. Developed by institute of electrical and electronics engg.
2. Upper freq. limit 100 GHz.
3. This standard is only applicable to an enclosure whose
smallest linear dimension is > 2mt.
4. It does not apply on small and medium size enclosure .
24
27. ASTM-E1851 :
1. Developed by the American society for testing and materials .
2. It requires freq. range between 140 and 160 KHz and between 14
to 16 MHz.
3. Far field shielding measurement between 300 to 500 MHz, 900
to 1000 MHz , and 8.5 and 10.5 GHz are required .
4. Used for large enclosure and shelters.
VG 95373 part 15 :
1. German military standard.
2. The freq. range above 30 to 200 MHz
3. Minimum antenna to enclosure separation distance of 2.5 mt.
4. Only standard applicable to small and medium sized enclosures.
27
28. ASTM-D 4935 :
1. Developed for evaluation of flat thin samples .
2. This standard is used for plastic materials .
3. Freq. range from 30 MHz to 100 MHz.
28
29. The EMR are increasing day by day due the increasing use of
electronics equipment and other sources of EMR . Since the EMR are
harmful for us, so it’s a big issue of concern. Due to the new
technologies and advancement such as use of conductive polymer
,multi layer fabrics and composites etc. the EMR hazards can be reduce
to some extent. After considering the different parameters of
construction for EMS , the effectiveness can be increased . In recent
year conductive fabric considered mainly due to their characteristics of
flexibility , lightness and competitive price.
29
30. 1. R Perumalraj, B.S. Dasaradan and are Nagaswarana, Electrically
conductive polymer materials for EMI Shielding, Asian Textile Journal,
Jan. 2009 (p- 49 to 57).
2. R Perumalraj, B.S. Dasaradan, Electromagnetic shielding fabric, Asian
Textile Journal , Oct. 2008 (p-62to 68).
3. R Perumalraj , B.S. Dasaradan , Electromagnetic shielding effectiveness
of copper core yarn knitted fabric , Indian Journal of Fibre and Textile
Research, vol-34 , June 2009 (p-149-154).
4. A.Das, V.K. Kothari, A. Kothari and A.Kumar, effect of various
parameter on EMS effectiveness of textile fabric , Indian Journal of
Fibre and Textile Research, vol-34 , June 2009 (p-144-148).
5. K.K.Gupta , S.M. Abbas and A.Srivastava, Microwave interactive fabric:
A review , Man Made Textiles in India , Feb 2012 (p-41t0 48).
6. P.R.Surwase, EMI shielding Material and measuring methods : A
Review , Man Made Textiles in India , Sep. 2011 (p-327 to 330).
7. Department of defense, United States of America,MIL – STD 285 .
8. V.K. Kothari ,Progress in Textile Science & Technology, vol. 3, (p-396).
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