Below are the questions asked during the live event, along with their respective answers.
Q: Hello, how can we distinguish by measurements if the coupling effect is more magnetic or electric?
A: These materials act mainly on the magnetic field, also because on the near field, the predominant field is the magnetic. To distinguish between them, different near field probes can be used (there are those for magnetic and for electric). Also, you can play with the polarization of the near field probe while measuring.
Q: On what frequency is the demonstration done?
A: In the 1MHz-1GHz range.
Q: What is the upper limit in frequency (GHz) where magnetic absorbers are effective?
A: There is no upper limit, depending on the material we can find absorbers working till higher frequencies than 60 GHz.
Q: During the video demo of the different thickness of the material, were the materials grounded or not? If they were not grounded, would better attenuation effects have been achieved if the materials were grounded?
A: These materials don´t need grounding, they are able to absorb /redirect and convert the noise into heat.
Q: Cavity Resonances diagrams: why does the reflection loss for 1.0mm material go up again at a certain frequency (all other thicknesses don’t show this behavior)?
A: The thickness of the material influences the attenuation that can be achieved and the frequencies where this attenuation is achieved. When using thicker materials, the attenuation is higher and the attenuation range decreases, shifting to lower frequencies.
Q: Is the distance between the magnetic shielding material and the transceiver influencing the performance of the energy/signal coupling?
A: The closer the shielding material to the source the better the performance.
Q: Probably on power transfer application mu’ is not actual, that means the simple magnetic shields can be applied?
A: No, it is necessary the using of materials with High mu’ (reflection) and low mu” (losses), it is important in order to avoid losses on the signal.
Q: Are the materials of these magnetic absorbers proprietary of Würth Elektronik? What is the differential of this product compared to other suppliers of magnetic absorbers?
A: Yes, these materials are produced by us. On the market the most common are the sintered ferrite sheet materials – these are more flexible, have better resistance against the environment, and are easy to customize.
Q: How much shielding is provided at power frequency by these materials?
A: It depends on the material, if you are interested you can check with us for more info.
Q: What are the magnetic absorber materials made from? Are the absorbers electrically conductive?
A: The FAS are composed by a mixture of rubber and ferromagnetic material, and they are not conductive, they have a surface resistance higher than 10MOhms on average