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

Junfeng,

One additional comment on the reason for the 30 Mhz boundary between =
radiated and conducted emissions.=20

Both regulations try to prevent unwanted radiated emissions. But we know =
that EUTs that are much smaller than the wavelength will not radiate =
directly very well, but they will excite the cables and then the cables =
will radiate. Thus, it is sufficient to measure the currents on the =
cables. The 30 MHz has been set on a typical EUT size of maybe 1 m. For =
radiated and conducted immunity the boundary is set at 80 Mhz but maybe =
varied depending on the DUT size.

Regards,

  David Pommerenke
  University Missouri Rolla



-----Urspr=FCngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx im Auftrag von =
Ravinder.Ajmani@xxxxxxxxxxxxxx
Gesendet: Mo 3/31/2008 11:16
An: jun feng
Cc: si-list@xxxxxxxxxxxxx
Betreff: [SI-LIST] Re: Difference between conducted and radiated =
emission ?
=20
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=20
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=20
cores run at hundreds of MHz and even GHz, so emissions caused by =
digital=20
switching will not show up as conducted emissions.  The core switching=20
will cause radiated emissions, which can couple to the outside world=20
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>=20
Sent by: si-list-bounce@xxxxxxxxxxxxx
03/31/2008 04:17 AM

To
si-list@xxxxxxxxxxxxx
cc

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






Hi,
  Can anyone tell me the difference between conducted and radiated=20
emission,
especially for digital circuits ?? For instance, inside a large size=20
digital
core what is responsible for the conducted and what is for radiated=20
emission
?
regards,


Junfeng


------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:=20
                                 =
http://www.freelists.org/archives/si-list
or at our remote archives:
                                =20
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                                 http://www.qsl.net/wb6tpu
=20




------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:    =20
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
 =20


------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

Other related posts: