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