Below are the questions asked during the live event, along with their respective answers.
Q: If we were to purchase a new chamber, how long would it take for the chamber to be up and running?
A: A component CISPR25 chamber will take approximately 4-5 months to construct and deliver to the customer ready to use. Vehicle-level testing will require a chamber that would likely take 1 year or more to become operational.
Q: What are “Hybrid” absorbers? Why should we use them instead of the old kind?
A: Hybrid absorbers use a combination of two absorber types.
- Ferrite tiles that provide good absorption from ~25-30 MHz to 1000 MHz.
- Foam absorbers will sit on the surface of the ferrite tiles and will provide good absorption from somewhere below 1000 MHz to more than 40 GHz.
The reason these will be desirable over a “Foam Only” solution is that the Hybrid absorbers are shorter and will allow the chamber to be constructed with smaller dimensions, saving money.
Q: For radiated emission tests, is it possible to place the antenna 1m from the device under test?
A: For testing up to 1 GHz, testing should be carried out 1m from the center of the harness.
For testing >1GHz, testing should be carried out with the centerline (phase center) of the horn antenna 1m away from the DUT
Q: How do you measure the 2.5 m Ohm for GND plane as the frequency increases for Impedance measurement?
A: This is typically accomplished using a Milli-Ohmmeter. It is a 4-wire measurement necessary to compensate for the impedance in the wires of the instrument. These instruments are commonly available. To make good measurement, the surfaces being measured MUST have a good connection, which means buffing and scrubbing away oxidation. You can do this with a scouring pad or steel wool.
Q: How frequent should testing be for NSA and SVSWR?
A: Annually, when troubleshooting an oddity in the measurement results, when replacing equipment that was found to be faulty, or when your Quality Manual dictates.
Q: Do the electrical field uniformity requirements apply to chambers acc 11452-2?
A: ISO 11452-2 does not directly call out making a Field Uniformity measurement, however, it is my personal opinion that Field Uniformity measurements should be executed in order to determine that the EUT is properly illuminated with the intended field strength or an acceptable deviation from the intended field strength. Any reference to IEC 61000-4-3 in an OEM specification will probably require a Field Uniformity measurement
Q: Does AR help to do maintenance for the chamber?
A: Any reputable chamber manufacturer should offer a maintenance program. AR does offer this service.