1.) I have an electronics board that has 10 wires coming out that gets conn
ected to an end users board with an Ethernet type cable. During our Elect
romagnetic 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 proble
m goes away.
3.) When the grounds and shield wires of the cable are pulled out of the ca
ble 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-boar
d solution on the PCB?