Well spotted, 6p and 20p are not so much difference for the results (for Low frequency), I think I may have two sim models there and I chose different values when I was building the models. I should have used the same value for consistency. Many thanks

Will do! It is in the plan

Hi Simba, i have a video on this. see kzfaq.info/get/bejne/oL-CZ5yGzM6ymmg.htmlsi=r94yUgrOPxvVn9wV

@MachOneDesignEMC Yes, I saw it a few months ago, and I still don't think ferrites can prevent RF interference from penetrating. also, do you think toroidal cores (iron powder cores) would work better for lower frequencies?

Yes, you got it. But we don't tend to match the physical length with electrical length. After all, it is only electrical length matter in a sense as waves propagate at a certain speed (in this case, less than the speed of light) in a given geometry of the transmission line.

I should have used this as a title, shouldn't I !

@@MachOneDesignEMC Showing you have a sense of humor, shows your intelligence ! 👍😉

Hi JiaLong, thanks, see this emccompliance.co.uk/wp-content/uploads/2022/03/The-magic-Loop-3.pdf . There is a lot more on emccompliance.co.uk feel free to share

@@MachOneDesignEMC Nice documents. Thanks a lot for sharing. 👍

See the new episode Mark!

Hi Tomas, hope you have now seen Episode 2 and 3, when constructed properly and terminated properly, the attenuation impact is actually quite insignificant.

@@MachOneDesignEMC If you want to observe the current in a conductor by the use of a B-field probe and then adds a ferrite/inductor on the wire you want to observe the characteristics of the ferrite must affect the current! I feel confused if it doesnt! Of course I understand that you will get better coupling to the probe pickup. I will have to look on your video clips again I think. Thanks/Tomas

Hi Tomas, you do ask hard questions! I did a little bit of research on this subject, guess what? The answer is very complicated, maybe I will do a special episode on this. But to summarise, it is not as simple as we thought that a ferrite core will attenuate signals. Think about it, when a probe is clamped on a wire, it also increases the inductance of the wire of the EUT, isn't it? Because effectively, now you have a wire through a core, so it is now a better inductor to some extent. So it is not a surprise, that the added series impedance to the circuit under test depends on many factors, the main ones being mutual coupling, self inductance of the current probe, self inductance of the wire under test and the coupling factor between the two. Very complicated stuff. Eventually, if a probe is terminated with 50 ohm, that 50 ohm impedance will be reflected back to the wire under test and thus reduce the effect of series added impedance. Hence, we should never leave an unconnected/unterminated current probe on the wire under test.

@@MachOneDesignEMC Yes, exactly my point! Everything gets complicated when looking into details! 🤣 Sorry if bothering you! /Tomas

This is a great question. I would assume yes

@@MachOneDesignEMC Thank you. I assumed so too, due to the fact that the device is plugged into the car's mains. However, when I started to check how the labs in China test it they don't use CISPR 25 standards at all (they don't use 5uH LISN etc.), they just "test" like a normal multimedia charger under CISPR 32 (EN 55032). The result is that it is difficult to find a car charger that does not cause interference - even audible on the radio, let alone passing EN 55025.... I have checked a dozen such chargers bought online and in supermarkets. And I began to wonder whether I was actually exceeding the requirements. There is also EN 50498 - but I don't have it and don't know what levels are required, nor do I have the receiver scripts for it.

Many thanks for your feedback and we will try our best.

He explained this at 1:29 . It isn't the repetition frequency of 250kHz that matters, it is the very fast rise time of the pulse. A 3ns pulse contains lots of harmonics much higher in frequency than 250 kHz. The 1/4 wave antenna is peferentially radiating those frequencies around 125 MHz. Higher and lower frequencies are coming out of the generator. If it was a 250 kHz sine wave instead of a pulse the rise time would be very slow and there wouldn't be any higher frequency components.

I am also curious of this

​@@furiousbullet hi, from the tekbox manual that you can find on the lisn manufacturer's website: if the DUT is grounded to the vehicle chassis with a power return line shorter than 20 cm, a single 5μH LISN is sufficient and the conducted noise will only be measured on the positive supply line. If the power return line of the DUT is longer than 20 cm, two 5μH LISNs are required. The positive supply line is connected to the DUT via one LISN and the power return line is connected to the DUT via another LISN.