Parallel Plate Mode on PCB

Hello,

to kill the PPM mode on a PCB with 50 um height between two GND planes,
we should place as much short-vias as possible. RIGHT ?

How many or in what distance should we do it.

frequency range 0.5.....30 GHz

Thanks for any comment

Hi, elektr0:

PPM is mainly caused by vias between layers and slots on the planes. You should put vias around vias and slots to make the 2 planes of equal potential locally. Certainly, the more you put, the better. However, adding more may not improve much afer you have put enough. For example, you put 4 grounding vias between a via between 2 layers. You may be able to suppress most of the PPM. Adding more there may just improve the performance further slightly.

Best regards,