Hello everyone.   
      
   1.) I have an electronics board that has 10 wires coming out that gets   
   connected to an end users board with an Ethernet type cable.   During our   
   Electromagnetic Compatibility (EMC) Testing for the RF Immunity Testing there   
   is a disturbance of our system    
   around 100-120 MHz and 1 GHz –2.7 GHz.  (Some of the values returned from   
   the Analog to Digital converter of our microcontroller show a noise   
   disturbance.)   
      
   2.) When a ferrite core clamp is connected over the entire cable the problem   
   goes away.   
      
   3.) When the grounds and shield wires of the cable are pulled out of the cable   
   and the ferrite core clamp is only applied to these wire (just 4 wires out of   
   the 10) the problem also goes away.   
      
   4.) There seems to be something going on when we apply a common-mode chock to   
   these ground / return paths.   
      
   5.) What is the best solution for something like this if we want on on-board   
   solution on the PCB?   
      
   Thank you.   
      
   -Mike   
      
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