A key component of EMC testing is the use of specialized antennas to transmit and receive electromagnetic signals. This article delves into the different types of antennas used in EMC testing, explaining their usage and characteristics.

Key Takeaways:

  • EMC testing ensures electronic devices operate without interference.
  • Different antennas are used for specific EMC testing purposes.
  • Understanding each antenna’s characteristics can optimize testing results.

Biconical Antennas

Biconical antennas are versatile and commonly used in EMC testing. They consist of two conical conductive objects, which can be adjusted to change the antenna’s characteristics.

Usage

Biconical antennas are primarily used for broadband EMC emissions and immunity testing. Their wide frequency range makes them suitable for various applications.

Advantages

  • Broadband Frequency Range: Can operate over a wide range of frequencies.
  • Adjustable Elements: The conical elements can be adjusted to optimize performance.
Biconical Antennas

Log-Periodic Antennas

Log-periodic antennas, often referred to as LPDAs (Log-Periodic Dipole Arrays), have a unique structure consisting of multiple elements that decrease in size towards the front of the antenna.

Usage

LPDAs are used for both emission and immunity testing in EMC. They offer a wide frequency range and are particularly effective for high-frequency testing.

Advantages

  • Wide Frequency Range: Suitable for high-frequency EMC testing.
  • Directional Characteristics: Offers high directivity, making it ideal for pinpoint measurements.
Log-Periodic Antennas

Horn Antennas

Horn antennas have a flared end, resembling a horn, which enhances their directional characteristics.

Usage

These antennas are used for high-frequency EMC testing, especially in the microwave range. They are ideal for both emission and immunity tests.

Advantages

  • High Directivity: Allows for precise measurements.
  • Broadband Performance: Suitable for a wide range of frequencies.
Horn Antenna

Loop Antennas

Loop antennas consist of a wire loop, which can be circular or rectangular. They are especially effective for magnetic field testing.

Usage

These antennas are primarily used for magnetic field measurements in EMC testing, especially at lower frequencies.

Advantages

  • Sensitive to Magnetic Fields: Ideal for detecting magnetic interference.
  • Compact Design: Suitable for testing in confined spaces.
Loop Antenna

FAQs

  1. What is required for shipping a device in the US/Canada that does not have a radio?
    • The US requires General Emissions Testing. Radiated tests are needed if the device is battery-powered. Both Radiated and Conducted tests are required if the device is powered by AC Mains. These are mandated per FCC Part 15B and ICES-003 for the US and Canada, respectively.
  2. How can I find out what antennas are FCC Certified with my module?
    • This information can be confirmed on the FCC site using the module’s FCCID and checking the module’s test reports.
  3. How do I use an antenna not listed on the module’s FCC Test Reports?
    • A Change of ID is required, followed by testing with the new antenna. A Class II Permissive Change is then done to move the new antenna test data into the new customer’s grant.

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Conclusion

Understanding the different types of antennas and their specific uses in EMC testing is crucial for obtaining accurate and reliable test results. By selecting the appropriate antenna for a given test scenario, engineers and technicians can ensure that electronic devices meet the necessary standards and operate without interference in their intended environments.

References:

  1. Constantin, A., & Tamas, R. (2020). Evaluation and Impact Reduction of Common Mode Currents on Antenna Feeders in Radiation Measurements.
  2. Abdulhameed, A., & Kubík, Z. (2022). Design a Compact Printed Log-Periodic Biconical Dipole Array Antenna for EMC Measurements.
  3. Mandaris, D., Moonan, N., Schuurmans, J., & Leferink, F. (2017). Comparison of log-periodic, dual-stacked log-periodic, and horn antenna on the field uniformity and power efficiency from 80 MHz to 1 GHz.
  4. Mandaris, D. (2020). High strength electromagnetic field generation for radiated EMI measurements.

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