FEDEVEL
Platform forum

552784 , 10-26-2023, 05:02 PM

Hi all,
Dos someone knows something about frame antenna or loop antenna creation due to a poor layout ?

I know an engineer, that does layouts, and in his 4 layer board he has 4 mounting holes on each corner, connected to protective earth. Just floating copper in normal operation.
What he does is that he creates a loop on top and bottom layer, with that potential, going from the first mounting hole, to the last one, but NEVER closes the loop. He left a gap.
On bottom side also?

What he says is that thus you will avoid antenna creation, like if it closes the loop

QDrives , 10-26-2023, 08:34 PM

Is it also connected so how to Gnd? If not, what is the use? Or is it a mains powered devices and that is connected to PE.

552784 , 10-27-2023, 08:19 PM

Protective earth.

QDrives , 10-27-2023, 10:04 PM

So it is only connected to PE and it is required as it is a class I device (mains powered with PE).
Not my expertise (antennas), but I can imagine that if you close it, you have a loop antenna. Leave it open and you have a dipole antenna (or monopole). Either way, it is an antenna. The only question is which would be worse...

552784 , 10-28-2023, 07:28 PM

Thanks!
Will see if I have enough time, just to test in a EMC lab both cases, but actually I needed to know if it can be considered as a general rule when doing the layout.that is what I was thinking of.
Simulating it can be tough task, and to get real overview of the problem, Ansys hfss or similar software will be needed as well. A powerfull PC also of course.