30 Questions
At what distance from the source do E and M fields develop into full electromagnetic fields?
One-sixth of the wavelength
What happens when the wavelength is comparable to the conductor length?
Resonances occur
What is the main purpose of conductors at high frequencies?
To cause radiated emissions and external field contamination
What is the conversion rate of signals to fields at certain frequencies?
Almost 100%
What happens when a conductor's length equals one-fourth of its wavelength?
It becomes a perfect converter of signals to fields
Why is it inadequate to treat conductors as merely electric or magnetic field emitters and receivers at high frequencies?
Because conductors behave as resonant antennas
What is compromised by additional resistance in the system?
Effective shielding
What is the primary pathway for RFI from a passenger PED?
Out the window and back into the plane via an antenna
What caused the Harrier Jump Jet's pilot to eject in the accident described?
Electromagnetic interference from the carrier's electronic equipment
What can allow EMI to enter the aircraft?
Unshielded openings in the plane
What is the primary reason why intentional radio frequency emitters are banned on commercial airline flights?
To prevent interference with the operation of sensitive electronic equipment
Which type of device is likely to produce signals in the 1-MHz range?
Laptop computer
Where was the navigation antenna located in the aircraft described?
Outside the aircraft skin
What type of engine was used in the Harrier Jump Jet?
Vectored thrust turbofan engine
Why are passengers sitting near navigation cabling and wiring warned about the use of personal electronic devices?
Because the devices can affect the performance of avionics equipment
Which of the following devices is not an intentional radio frequency emitter?
Laptop computer
What is the main concern regarding the use of personal electronic devices on commercial airline flights?
Electromagnetic interference with avionics equipment
Which of the following is a common source of electromagnetic interference?
All of the above
What method can be used to control the amount of EMI produced by a radio transmitter?
Cutting transmitting antennas to the correct frequency
How can radiated EMI during transmission be controlled?
By using directional antennas and limiting antenna bandwidth
What is a benefit of using fibre optics in aviation?
They are completely immune to EMI
Why are fibre optics being used to replace traditional copper conductors?
Because they eliminate the many risks and problems of EMI
What is the result of using fibre optics in fly-by-wire systems?
The elimination of the many risks and problems of EMI
What is being replaced by fibre optics in many retrofit projects?
Copper conductors
What is the primary source of High-Intensity Radiated Field (HIRF) emissions?
Airport radar systems
What type of interference does HIRF not include?
Interference among on-board systems
What is the effect of lightning on aircraft and avionics systems similar to?
Low-frequency HIRF emissions
What is the concern regarding Personal Electronic Devices (PEDs) carried by passengers?
They can interfere with aircraft systems
What is Electrostatic Discharge (ESD)?
The effect of static electricity generated on the aeroplane
What is the name of the issue that refers to interference among on-board systems?
Electromagnetic Compatibility (EMC)
Learn about the importance of effective shielding in aircraft systems to prevent electromagnetic interference (EMI) and radio-frequency interference (RFI) from passenger devices.
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