FCC RF Emissions & Electromagnetic Compatibility 1 — Questions and Answers
Question 1: What does EMC stand for in the context of FCC certified laboratory testing?
- Electromagnetic Compatibility (Correct answer)
- Electronic Measurement Calibration
- Emission Measurement Control
- Equipment Manufacturing Compliance
Correct answer: Electromagnetic Compatibility
EMC stands for Electromagnetic Compatibility, which refers to a device's ability to function correctly without causing or being affected by electromagnetic interference.
Question 2: Which FCC Part covers radiated and conducted emission limits for unintentional radiators?
- Part 15 (Correct answer)
- Part 22
- Part 90
- Part 97
Correct answer: Part 15
FCC Part 15 establishes the technical standards and operational requirements for unintentional, intentional, and incidental radiators, including radiated and conducted emission limits.
Question 3: What is the primary purpose of a shielded anechoic chamber in EMC testing?
- To eliminate external electromagnetic interference and absorb internal reflections (Correct answer)
- To amplify weak signals for measurement
- To calibrate spectrum analyzers
- To store reference antennas
Correct answer: To eliminate external electromagnetic interference and absorb internal reflections
A shielded anechoic chamber blocks external RF signals and uses RF-absorbing materials on walls to prevent signal reflections, simulating free-space conditions for accurate emissions measurement.
Question 4: What is the standard test distance commonly used for FCC radiated emissions measurements on devices operating below 1 GHz?
- 3 meters (Correct answer)
- 1 meter
- 10 meters
- 30 meters
Correct answer: 3 meters
FCC Part 15 typically requires radiated emissions measurements at a 3-meter test distance for devices operating below 1 GHz when tested in a semi-anechoic chamber.
Question 5: Which type of antenna is most commonly used for radiated emissions measurements in the 30 MHz to 1 GHz range?
- Biconical and log-periodic (LPDA) antennas (Correct answer)
- Parabolic dish antenna
- Yagi antenna
- Loop antenna only
Correct answer: Biconical and log-periodic (LPDA) antennas
Biconical antennas cover the 30–200 MHz range and log-periodic dipole array (LPDA) antennas cover 200 MHz–1 GHz, together providing full coverage for the standard test range.
Question 6: What is the definition of a 'conducted emission' in FCC testing?
- Unwanted RF energy transmitted back through the power line (Correct answer)
- RF energy radiated through the air from a device
- Interference caused by mechanical vibration
- Emissions from intentional transmitters only
Correct answer: Unwanted RF energy transmitted back through the power line
Conducted emissions are unwanted RF voltages or currents that travel back through the AC power cord into the public utility power line, potentially causing interference to other devices.
FCC RF Emissions & Electromagnetic Compatibility 1
What does EMC stand for in the context of FCC certified laboratory testing?