[SI-LIST] Re: Difference between conducted and radiated emission ?

Hi Junfeng,
Your question is more appropriate for the EMC Discussion Group.  However 
since I wear both the hats, I may be able to give you an answer.

The main difference between Conducted and Radiated emissions is in the 
frequency range.  Conducted emissions are measured off the power cord of 
your system between 150 kHz and 30 MHz.  Radiated emissions are measured 
from 30 MHz to 1GHz and higher, depending on the highest frequency being 
generated in your system.

The main causes of conducted emissions are the switching power supplies, 
and low frequency digital circuits (which clock below 30 MHz).  The modern 
cores run at hundreds of MHz and even GHz, so emissions caused by digital 
switching will not show up as conducted emissions.  The core switching 
will cause radiated emissions, which can couple to the outside world 
through PCB traces, or common-mode coupling from Power and Ground planes.

Regards, Ravinder
Server PCB Development
Hitachi Global Storage Technologies


Email: Ravinder.Ajmani@xxxxxxxxxxxxxx



"jun feng" <junfeng.zhou@xxxxxxxxx> 
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[SI-LIST] Difference between conducted and radiated emission ?






Hi,
  Can anyone tell me the difference between conducted and radiated 
emission,
especially for digital circuits ?? For instance, inside a large size 
digital
core what is responsible for the conducted and what is for radiated 
emission
?
regards,


Junfeng


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