I have a customer who has asked me if I know about shielding vias. I don't know much about these. All I know is that the size of the PTH and the distance apart are based, somehow, on what frequency the logic (PCB) is operating at. (Yessss?) Now I don't have IEEE text books anywhere near this facility. I'm a simple fabricator. Can someone who's savvy with RF <or even Microwave> design give me some pointers to what kind of formulas are used to determine this shield via barrier technique. Thanks in advance for any and all replies. Groovy