Below are the questions asked during the live event, along with their respective answers.
Q: Are Spectrum Analyzers like these only useful for debugging EMI issues or can they be used in other ways as well?
A: Real-Time Spectrum Analyzers are great for Spectrum Monitoring, testing RF designs & components, and verifying Transmitter configurations. They are important in many design and debug applications including almost all of the EMI pre-compliance measurements.
Q: I am new to Pre-Compliance Measurements. Where should I start in building up these test capabilities?
A: Pre-compliance measurements are all about getting your device or project through compliance faster and easier. Build up the test capabilities where you have had issues or concerns first. Radiated measurements with a spectrum analyzer and near field probe are a great place to start. Using a LISN to make conducted emission measurements or add a signal source to test immunity. The important thing is to be able to capture and analyze the measurements you need to solve the most important concerns facing your project.
Q: Are MIL-STD limits included with the RSA3000-EMI?
A: There are over 300 limit lines in the EMI software for the RSA instruments. Many are related to different standards including military. Please contact us directly for a demonstration or full list of the related limit lines.
Q: What’s the difference between TEM and GTEM?
A: GTEM Cells provide extended frequency and are pyramidal in shape. They tend to be larger than standard TEM Cells. The extended frequency range allows them to meet some additional standards for radiated or immunity testing.
Q: Do we require a EMI receiver or a real-time spectrum analyzer for a pre-compliance setup?
A: Pre-compliance measurements can be made in a number of different ways because they don’t need to meet the criteria for final compliance testing. Anything that helps you improve your design and chances of passing compliance testing can be good for a pre-Compliance setup. We find that a real-time spectrum analyzer provides all the feedback needed for testing and debugging devices in this mode. A swept spectrum analyzer makes many of these measurements but doesn’t provide as much debug capability especially for higher speed, transient emissions. An EMI Receiver is typically considerably more expensive and provides very little additional value without a full compliance standard test setup.
Q: Is there a recommended distance from the noise source measured with a near probe measurement which will then correlate to a radiated emissions measurement in the far field?
A: Great question. There is no easy way to convert near field measurements to far-field levels. Some accessories like a TEM Cell can to approximate overall field strength but these are still near field measurements. There isn’t a correlation between the two, but our customers find that with a specific device type they can identify problem areas and find solutions using the near field measurement techniques.