ELECTROMAGNETIC INDUCTION - AN INTRODUCTION

ELECTROMAGNETIC INDUCTION - AN INTRODUCTION

1. ELECTROMAGNETIC INTERFERENCE (EMI) SHIELDING TAMILMOZHI M RESEARCH SCHOLAR SRMIST VDP,CHENNAI-26

2. CONTENTS INTRODUCTION ELECTEROMAGNETIC INTERFERENCE (EMI) SOURCES OF EMI EMI SHIELDING SHIELDING EFFECTIVENESS SHIELDING MECHANISM APPLICATIONS CONCLUSION

3. INTRODUCTION Electromagnetic Interference (EMI) is a form of electronic "noise" that can disrupt the operation of electronic devices. EMI shielding is a fundamental technique used to protect sensitive electronics from interference and to prevent a device from emitting its own interference. Electromagnetic Interference Shielding , is a fundamental technique used in electrical engineering and electronics to prevent unwanted electromagnetic energy from disrupting the proper functioning of electronic devices or systems.

4. ELECTROMAGNETIC INTERFERENCE (EMI) Electromagnetic Interference (EMI), also known as radio-frequency interference (RFI) when it occurs in the radio frequency spectrum, is a disturbance or "noise" that affects an electrical circuit. This disturbance is generated by an external source and can degrade the performance of the circuit or even cause it to malfunction or stop working entirely.

5. SOURCE OF EMI Natural EMI Sources : These are phenomena that occur naturally and generate electromagnetic energy .like Lightning strikes, Solar flares and solar storms, Cosmic noise, Electrostatic discharge (ESD). Man-Made EMI Sources: These are generated by electronic devices and electrical systems created by humans. like Electronic Devices, Wireless Communication

6. TYPES OF EMI By Coupling Mechanism Conducted EMI Radiated EMI Coupled EMI By Bandwidth Narrowband EMI Broadband EMI By Duration Continuous EMI Impulse ( Transient ) EMI

7. EMI SHIELDING EMI Shielding refers to the process of using materials or enclosures to block or reduce these unwanted electromagnetic signals from: Entering a device (external EMI) Leaving a device (internal EMI)

8. SHIELDING EFFECTIVENESS Shielding Effectiveness is the ability of a material or enclosure to block or reduce electromagnetic interference (EMI) . It measures how well the shield attenuates (reduces) the electromagnetic field. The higher the SE value, the better the shielding. It's usually expressed in decibels (dB). FORMULA: SE (dB)=20log⁡ 10 (E 1/ E 2 ) Where: E 1 ​- Electric field strength without the shield E 2 ​-Electric field strength with the shield log⁡10​- Logarithm to base 10

9. A decibel (dB) is a unit of measurement that is used to express the ratio of two values of a physical quantity, such as power or sound pressure, on a logarithmic scale. It's a relative unit, not an absolute one, meaning it always compares a value to a reference value. DEFINITION OF DECIBEL

10. SHIELDING MECHANISM EMI shielding mainly works through: Reflection of EM waves at the surface Absorption within the shielding material Multiple internal reflections (sometimes) The total shielding effectiveness is the sum of these three components: SE(dB)=R(dB)+A(dB)+M(dB)

11. Factors Affecting Shielding Effectiveness: Material conductivity (e.g., copper > polymer) Thickness of shield Frequency of the EMI signal Permeability and structure of the material Number of reflections inside the material

12. SHIELDING MATERIALS Metals High shielding effectiveness eg ,. Copper, Aluminum , Nickel Carbon-based Lightweight, flexible eg ,. CNTs, Graphene , Carbon black Polymer composites Flexibility + durability eg ,. Conductive polymers, metal-polymer mix Coatings Surface-level shielding eg ,. EMI paint, films, foils

13. APPLICATIONS 1. Electronic Devices Protects smartphones, laptops, and TVs from external EMI. Prevents internal components from interfering with each other. Ensures smooth functioning of microprocessors and sensors. 2. Aerospace and Defense Critical in aircraft, satellites, and military equipment. Shields radar, navigation, and communication systems from external noise. Increases safety and signal integrity. 3. Automotive Industry Modern vehicles contain many electronic control units (ECUs). EMI shielding is used to prevent signal crossover between sensors, cameras, and infotainment systems.

14. 4. Medical Equipment Shields MRI, ECG, and infusion pumps from electromagnetic noise. Ensures accuracy and reliability of diagnosis and monitoring. 5. Industrial Equipment Protects automation systems, PLCs, and robots from external EMI. Prevents signal errors in high-frequency industrial environments. 6. Communication Systems Enhances performance of Wi-Fi, Bluetooth, and cellular devices. Prevents cross-talk and interference in cables and antennas . 7. Research and Laboratory Instruments EMI shielding chambers and enclosures used to test devices in controlled EMI-free environments.

15. CONCLUSION EMI shielding is a technique of creating a barrier that prevents leakage of strong electromagnetic fields that can interfere with sensitive devices and signals. Electromagnetic interference (EMI) is the coupling of signals from one system to another. It is a problem for most electronics since it can decrease the performance of the circuit or even cause it to fail. EMI shielding operates under three mechanisms: reflection, absorption, and multiple reflections. Two main properties achieve EMI shielding: electrical conductivity and magnetic permeability. EMI shields are available as solid enclosures, wire mesh, screens, cable shields, and coatings.

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