Intro
Otto-von-Guericke-Universität Magdeburg Electromagnetic Compatibility in everyday lifeWhy you can´t use a cell phone on a plane?
Welcome!Dr.-Ing. Mathias Magdowski
Chair for Electromagnetic Compatibility
Institute of Medical Engineering
Otto-von-Guericke-Universität Magdeburg
Institute of Medical Engineering
Otto-von-Guericke-Universität Magdeburg
Outline
What is Electromagnetic Compatibility (EMC)?
What’s behind it?
How to investigate EMC?
Where do electromagnetic incompatibilities occur in everyday
life?
What’s behind it?
How to investigate EMC?
Where do electromagnetic incompatibilities occur in everyday
life?
EMC
What is EMC?
DefinitionElectromagnetic Compatibility is the ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to other equipment in that environment.
What is EMC?Electromagnetic Compatibility
There are two aspects of electromagnetic compatibility:
Immunity (Susceptibility) . . .
means the ability of equipment to perform as intended without degradation in the presence of an electromagnetic disturbance.
Emission (Disturbance) . . .
means any electromagnetic phenomenon which may degrade the performance of equipment. An electromagnetic disturbance may be electromagnetic noise, an unwanted
signal or a change in the propagation medium itself.
Immunity (Susceptibility) . . .
means the ability of equipment to perform as intended without degradation in the presence of an electromagnetic disturbance.
Emission (Disturbance) . . .
means any electromagnetic phenomenon which may degrade the performance of equipment. An electromagnetic disturbance may be electromagnetic noise, an unwanted
signal or a change in the propagation medium itself.
What´s behind it?Interference model
Investigation EMC
How to investigate the electromagnetic compatibility?
There are three main options ...
Verification of equipment byCalculation
Verification of equipment bySimulation
Verification of equipment byMeasurements
Measuring devices such as spectrum analyzers are used to measure what kind of electrical and magnetic field strength a test object generates at a certain distance. This is compared with standards and limit values.
There are different measurement environments:
There are different measurement environments:
Practice
Where do electromagnetic incompatibilities occur in everyday life?Examples
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Amplitude-modulated signal
Antenna
Active speaker with diodes
Envelope after demodulation
Mobile phone radiationCountermeasures
YOUR TASK:
Please select an appropriate countermeasure to stop the noise in the speaker caused by mobile phone radiation!
Please select an appropriate countermeasure to stop the noise in the speaker caused by mobile phone radiation!
Mobile phone radiationMore Examples
Cell phone radiation can also have greater effects in everyday life,
when radio waves from the cell phone ...
- interfere with medical equipment in hospitals
- affect assistance systems in cars
- or on an airplane ...
Initial question
Why you can´t use a cell phone on a plane?
Lightning discharges
ReasonsLightning discharges
- friction and strong up winds inside a thunderstorm cloud
- separation of electrical charges
- electrical spark → very strong current
EffectsLightning discharges
- “step voltage” at the ground near the striking point
- domestic coals and forest fires
- coupling into the mains grid and into antennas
CountermeasuresLightning discharges
persons
buildings
vehicles
electrical equipment
- take cover
- feet close together
buildings
- lightning arrester
vehicles
- Faraday cage
electrical equipment
- overvoltage protection
Electrostatic discharge
ReasonsElectrostatic discharge
- low humidity
- triboelectricity e. g. while walking on a carpeted floor
- large potential difference → spark or breakdown
EffectsElectrostatic discharge
- short voltage impulse with high amplitude (ESD – electrostatic discharge)
- degradation of electronic components in devices
- uncontrolled ignition of inflammable gases
CountermeasuresElectrostatic discharge
- protective elements in electronic devices
- testing of devices with standard pulses from ESD guns
- caution while handling unprotected modules
- ESD-safe packaging
Open-area test site
Open-area test site
Semi-anechoic chamber
Semi-anechoic chamber
Reverberation chamber
Reverberation chamber
Coupling paths
Coupling mechanismConducted
Coupling mechanismElectric fields
Coupling mechanismMagnetic fields
Coupling mechanismWave fields
Countermeasures
Metal box
Countermeasures
Lower Volume
Countermeasures
Ferrites
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Electromagnetic Compatibility in everyday life
Intro
Dr.-Ing. Mathias Magdowski
Outline
What is EMC?
Electromagnetic Compatibility is the ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to other equipment in that environment.
Interference model
Coupling mechanism
Calculation
Simulation
Mobile phone radiation
Active principle
Measurement
More Examples
Why you can´t use a cell phone on a plane?
Questions?
Lightning discharges
Lightning discharges
Lightning discharges
Electrostatic discharge
Electrostatic discharge
Electrostatic discharge
Open-area test site
Semi-anechoic chamber
Reverberation chamber
Conducted
Electric fields
Magnetic fields
Wave fields
Metal box
Lower Volume
Ferrites