RE: SAR Measurements

[UMBDENSTOCK]

Lothar,

The FCC uses an unusual splitting of hairs regarding "categorically
excluded".  This means you are not required to do the SAR measurement or
analysis; but, you must still prove compliance by methods such as
identifying the radiated power and establishing the separation distance of
John Q Public from the radiating element.  The requirements vary according
to whether the product is fixed external (e.g. roof mounted), fixed internal
(inside a facility where persons are likely to be in proximity), mobile
(antenna separate from electronics), or portable (i.e., in intimate contact
with the body).  

These differences are crucial in determining whether one can apply MPE
formulas or whether SAR needs to be addressed.

There must be a "magic" threshold" as TCBs are allowed to approve some
devices (I would interpret that to mean "no exposure risk") but not others.
TCBs are allowed to approve devices that meet certain requirements such as
power output threshold and radiator set backs for 15.247, but I do not have
the URL on which  the TCB rules list is located.  I assume that the ISM band
must have something similar.

Curtis-Strauss is well versed in TCB issues.  I would suspect that they
would have  knowledge of the limitations if any TCB did.  If you wish to go
straight to the source for exposure issues, that would be a Mr. Kwok Chan at
the FCC.

I know this did not answer your question directly, but I hope it helped.

Don Umbdenstock



> --
> From: Wismer, Sam[SMTP:wisme...@lxe.com]
> Reply To: Wismer, Sam
> Sent: Friday, October 20, 2000 2:30 PM
> To:   Lothar Schmidt; EMC-PSTC (E-mail)
> Subject:  RE: SAR Measurements
> 
> 
> Lothar,
> As you already know I'm sure, part 15 devices are categorically excluded
> from routine environmental evaluation.  But that doesn't stop the FCC from
> hounding you about it everytime you send up an application.  I routinely
> get
> a request from the FCC of how I comply with section 15.247(b)(4) which is
> about the most vague section in the book.  However, after following all
> the
> "refer to's", section 2.1093(c) that states part 15 devices(not all, but
> most), are categorically excluded.  After many debates with the FCC, what
> I
> have come to realize is that, although part 15 devices are categorically
> excluded, the FCC reserves the right to mandate an applicant to show
> compliance to the SAR requirements and perform the measurements.  
>  
> To answer your question about where it is written that any device less
> than
> 1mW is exempt, I haven't seen such a document, but I have been told that
> the
> FCC has an unwritten threshold of about 200mW for ISM equipment and will
> not
> require testing.  Our ISM radios, which are up to 100mW, have never been
> required by the FCC to submit to SAR evaluation.  In my applications, I
> provide MPE calculations for our Mobile equipment and for our portable
> equipment I simply cite section 2.1093 and reference OET Bulletin 65,
> Supplement C.   However, if your market includes Canada, all this is now
> moot since RSS 102 includes ISM devices and you have to do the test
> anyway.
> 
>  
> 
> 
> ~ 
> Sam Wismer 
> Lead Regulatory Engineer/ 
> Radio Approvals Engineer 
> LXE, Inc. 
> (770) 447-4224 Ext. 3654 
> 
> Visit Our Website at: 
> http://www.lxe.com   
> 
>  
> 
> -Original Message-
> From: Lothar Schmidt [mailto:lothar.schm...@cetecomusa.com]
> Sent: Friday, October 20, 2000 12:01 PM
> To: EMC-PSTC (E-mail)
> Subject: SAR Measurements
> 
> 
> Hi group,
>  
> Does anybody know a source where is written that a portable device (spread
> spectrum in the 24 gHz range) under OET 65 has not to be measured
> regarding
> SAR if the radiated power is less than 1 mW (0 dBm)?
> Or is this only the experience that these kind of devices never exeed the
> limits of table 2?
>  
> Any hint welcome
>  
> Thanks
> 
> Best Regards 
> 
> Lothar Schmidt 
> Technical Manager EMC/Bluetooth, 
> BQB, Competent Body 
> Cetecom Inc. 
> 411 Dixon Landing Road 
> Milpitas, CA 95035 
> Phone: +1 (408) 586 6214 
> Fax: +1 (408) 586 6299 
> 
>  
> 
> 
> ---
> This message is from the IEEE EMC Society Product Safety
> Technical Committee emc-pstc discussion list.
> 
> To cancel your subscription, send mail to:
>  majord...@ieee.org
> with the single line:
>  unsubscribe emc-pstc
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> 
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>  Richard Nute:   ri...@ieee.org
> 
> 

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RE: Holes, wave guides and honeycombs

[William D'Orazio]

Gary,

Actually a formula that I have contains the hole thickness, hole
diameter, section length and number of holes, and I would guess that the
formula was developed based on an equal spacing approach.
In addition the SE does depend on the distance from source to
shield.  In the near field the SE would also depend whether the source is a
high(electric) or low(magnetic) impedance source.
I don't see, however, how you could conclude that the performance degrades
when the source approaches the shield.

Best Regards,

William D'Orazio
CAE Electronics Ltd.
Electrical System Designer

Phone: (514) 341-2000 (X4555)
Fax: (514)340-5552
Email: dora...@cae.ca


-Original Message-
From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com]
Sent: Friday, October 20, 2000 12:56 PM
To: 'jim_bac...@mail.monarch.com'; Paolo Roncone;
emc-p...@majordomo.ieee.org
Subject: RE: Holes, wave guides and honeycombs



Good question. I was just digging around for that information my self so I
am waiting with baited breath the responses, and have a question. 
The question deals more with aperture such as is found in general
computing equipment enclosure sheet metal, rather than a wave guide which
also has some significant thickness to it.

1)If there is multiple apertures doesn't the distance between each aperture
matter as well, and the distance between source and aperture significant?
Placing them too close together effectively makes them appear as a single
much larger opening, and moving the source very close to the opening
degrades the shielding effectiveness? 




-Original Message-
From: jim_bac...@mail.monarch.com [mailto:jim_bac...@mail.monarch.com]
Sent: Friday, October 20, 2000 7:31 AM
To: Paolo Roncone; emc-p...@majordomo.ieee.org
Subject: Re:Holes, waveguides and honeycombs



forwarding for pronc...@cisco.com

Reply Separator
Subject:Holes, waveguides and honeycombs
Author: Paolo Roncone 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 12:03 PM

Group,

We are working on a couple of designs of telecom gear contained in metal 
s.u.b.-racks and we have to meet emission limits up to 40 GHz.
I need some advice on the workings of waveguides below cut-off and 
honeycombs, because we have to include ventilation openings without 
possibly degrading the shielding effectiveness.
First, I made an inquiry on textbook formulas for circular and rectangular 
waveguide cut-off frequencies. I was happy to find consistency among three 
different sources (I found the same formulas although rearranged in 
different fashions).
 From Ott's "Noise reduction techniques in electronic systems" I found:

fc = [6.9/d] GHz   for circular waveguides

fc = [5.9/l] GHz  for rectangular waveguides

where fc = cutoff frequency
d = diameter of circular section (inches)
l = longer side of rectangular section (inches)

Now my question is: what about honeycomb panels ?
Can I use the same formulas for honeycombs ? Here the single cells are 
neither circular nor rectangular. Can I still apply these formulas with 
good accuracy ? If not, anyone knows of other formulas that apply in this
case?
As for attenuation (shielding effectivenes) of one single waveguide 
opening, if  the frequency is well below cutoff , this is proportional to 
the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
to 4:1 in order to get good attenuation.

Now, I just found a formula for attenuation of honeycomb panels as function 
of frequency, length-to-width ratio of each cell and also number of cells:

S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)

where:

S [dB] = Shielding Effectiveness in dB
fc = cutoff frequency of waveguide
f = frequency
t = cell length (or thickness)
W = cell section width
n = number of cells in honeycomb panel

I have no problems with the first two terms in the above equation. As for 
the third term, that means that increasing the number of cells (n) in the 
honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
1000 cells means 30 dBs lost).
Before finding this formula I had a feeling that due to the skin-effect 
each honeycomb cell could be treated as a single cell.
So far I wasn't able to find other formulas for honeycomb panels. So I'd 
like to have some feedback on this.
I hope to get some useful directions.

Thank you in advance,

Paolo Roncone
Cisco Photonics, Italy

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--

RE: SAR Measurements

[Wismer, Sam]

Lothar,
As you already know I'm sure, part 15 devices are categorically excluded
from routine environmental evaluation.  But that doesn't stop the FCC from
hounding you about it everytime you send up an application.  I routinely get
a request from the FCC of how I comply with section 15.247(b)(4) which is
about the most vague section in the book.  However, after following all the
"refer to's", section 2.1093(c) that states part 15 devices(not all, but
most), are categorically excluded.  After many debates with the FCC, what I
have come to realize is that, although part 15 devices are categorically
excluded, the FCC reserves the right to mandate an applicant to show
compliance to the SAR requirements and perform the measurements.  
 
To answer your question about where it is written that any device less than
1mW is exempt, I haven't seen such a document, but I have been told that the
FCC has an unwritten threshold of about 200mW for ISM equipment and will not
require testing.  Our ISM radios, which are up to 100mW, have never been
required by the FCC to submit to SAR evaluation.  In my applications, I
provide MPE calculations for our Mobile equipment and for our portable
equipment I simply cite section 2.1093 and reference OET Bulletin 65,
Supplement C.   However, if your market includes Canada, all this is now
moot since RSS 102 includes ISM devices and you have to do the test anyway.

 


~ 
Sam Wismer 
Lead Regulatory Engineer/ 
Radio Approvals Engineer 
LXE, Inc. 
(770) 447-4224 Ext. 3654 

Visit Our Website at: 
http://www.lxe.com   

 

-Original Message-
From: Lothar Schmidt [mailto:lothar.schm...@cetecomusa.com]
Sent: Friday, October 20, 2000 12:01 PM
To: EMC-PSTC (E-mail)
Subject: SAR Measurements


Hi group,
 
Does anybody know a source where is written that a portable device (spread
spectrum in the 24 gHz range) under OET 65 has not to be measured regarding
SAR if the radiated power is less than 1 mW (0 dBm)?
Or is this only the experience that these kind of devices never exeed the
limits of table 2?
 
Any hint welcome
 
Thanks

Best Regards 

Lothar Schmidt 
Technical Manager EMC/Bluetooth, 
BQB, Competent Body 
Cetecom Inc. 
411 Dixon Landing Road 
Milpitas, CA 95035 
Phone: +1 (408) 586 6214 
Fax: +1 (408) 586 6299 

 


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Re: Virus

[dBaron]

At 11:25 AM 10/20/00 -0400, Pryor McGinnis wrote:

If you receive an email with subject "US PRESIDENT AND FBI SECRETS"
DO NOT OPEN IT!  IT IS A VIRUS
It will overwrite files with extensions .vbs,.vbe,  .js,.jes,.css,.wsh, 
.sct,.jpg,.jpeg,.mp3, and .mp2.


Best Regards,
Pryor McGinnis


For once a real virus 
(http://www.symantec.com/avcenter/venc/data/vbs.loveletter.as.html):


Symantec has received inquiries regarding a worm that spreads itself via 
email with the subject "US PRESIDENT AND FBI SECRETS=PLEASE VISIT". Norton 
AntiVirus detects this worm as VBS.Plan.A. Protection against this worm has 
been available for users of Norton AntiVirus since June 15, 2000. Symantec 
encourages users of Norton AntiVirus to keep their virus definitions up to 
date to ensure that they always have the latest protection.

RE: Holes, waveguides and honeycombs

[Maxwell, Chris]

Paolo,

I looked in the "Shielding Design Guide" by Tecknit and found the same
formula that you have below.  

The formula is claimed to be relavant for threat frequencies that are less
than one tenth of the cutoff frequency(fc).  This may be of some importance,
because their claimed cutoff frequency for 1/8" honeycomb is 47GHz.  If your
application runs up to 40GHz, you will be over the fc/10 limit for the
formula's usefulness.  I would still use the formula as a guide, but beware!

Another concern that I have is from looking through graphs of shielding
effectiveness in the Instrument Specialties catalog for honeycomb.  They
seem to be concerned with the specific metal and plating used to make the
contact around the edge of the honeycomb vent.   I would recommend taking
care to make sure you get a good seal.  After all, what good is a honeycomb
with 90dB of attenuation if it has a leaky seal around the edge?  At 40Mhz,
it would be easy for the seal around the honeycomb to become a leakage
factor.

I liked Derek's (another response) idea of putting a bend in the cooling
airflow path with some ferrite absorber.  I've never thought of it, but it
sounds like it may offer some improvement (if you think you need it).  I've
never seen experimental proof of this, but maybe someone else has.  

By the way, page 150 of the Instrument Specialties Catalog and Design Guide
has a graph for determining the required vent size for a given amount of
airflow and static pressure.  I assume that you have already determined your
vent size, but if you haven't, this graph may help.

Chris Maxwell, Design Engineer
GN Nettest Optical Division
6 Rhoads Drive, Building 4  
Utica, NY 13502
PH:  315-797-4449
FAX:  315-797-8024
EMAIL:  chr...@gnlp.com


> -Original Message-
> From: jim_bac...@mail.monarch.com [SMTP:jim_bac...@mail.monarch.com]
> Sent: Friday, October 20, 2000 10:31 AM
> To:   Paolo Roncone; emc-p...@majordomo.ieee.org
> Subject:  Re:Holes, waveguides and honeycombs
> 
> 
> forwarding for pronc...@cisco.com
> 
> Reply Separator
> Subject:Holes, waveguides and honeycombs
> Author: Paolo Roncone 
> Date:   10/20/00 12:03 PM
> 
> Group,
> 
> We are working on a couple of designs of telecom gear contained in metal 
> s.u.b.-racks and we have to meet emission limits up to 40 GHz.
> I need some advice on the workings of waveguides below cut-off and 
> honeycombs, because we have to include ventilation openings without 
> possibly degrading the shielding effectiveness.
> First, I made an inquiry on textbook formulas for circular and rectangular
> 
> waveguide cut-off frequencies. I was happy to find consistency among three
> 
> different sources (I found the same formulas although rearranged in 
> different fashions).
>  From Ott's "Noise reduction techniques in electronic systems" I found:
> 
> fc = [6.9/d] GHz   for circular waveguides
> 
> fc = [5.9/l] GHz  for rectangular waveguides
> 
> where fc = cutoff frequency
> d = diameter of circular section (inches)
> l = longer side of rectangular section (inches)
> 
> Now my question is: what about honeycomb panels ?
> Can I use the same formulas for honeycombs ? Here the single cells are 
> neither circular nor rectangular. Can I still apply these formulas with 
> good accuracy ? If not, anyone knows of other formulas that apply in this
> case?
> As for attenuation (shielding effectivenes) of one single waveguide 
> opening, if  the frequency is well below cutoff , this is proportional to 
> the ratio of length/diameter of the waveguide. The recommended ratio is
> 2:1 
> to 4:1 in order to get good attenuation.
> 
> Now, I just found a formula for attenuation of honeycomb panels as
> function 
> of frequency, length-to-width ratio of each cell and also number of cells:
> 
> S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)
> 
> where:
> 
> S [dB] = Shielding Effectiveness in dB
> fc = cutoff frequency of waveguide
> f = frequency
> t = cell length (or thickness)
> W = cell section width
> n = number of cells in honeycomb panel
> 
> I have no problems with the first two terms in the above equation. As for 
> the third term, that means that increasing the number of cells (n) in the 
> honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
> 1000 cells means 30 dBs lost).
> Before finding this formula I had a feeling that due to the skin-effect 
> each honeycomb cell could be treated as a single cell.
> So far I wasn't able to find other formulas for honeycomb panels. So I'd 
> like to have some feedback on this.
> I hope to get some useful directions.
> 
> Thank you in advance,
> 
> Paolo Roncone
> Cisco Photonics, Italy
> 
> ---
> This message is from the IEEE EMC Society Product Safety
> Technical Committee emc-pstc discussion list.
> 
> To cancel your subscription, send mail to:
>  majord...@ieee.org
> with the single line:
>  unsubsc

Re: Got a beef with an NRTL ...

[E Eszlari]

Doug,

I agree with Peter. When I was at TUV I had investigated products along with 
the UL Engineer who never had a problem with using an AC rated fuse to 
protect a DC rated product, as long as it did it's job. However, when UL 
sent another Engineer for a DC product investigation he required that the AC 
fuse be replaced with one that had a DC rating. Obviously a major problem 
for the company since UL has accepted this practice in the past.


I believe as long as the fuse is located within the product and protects the 
product from any hazards as stated within the testing standard, it should be 
acceptable.


Ed



From: peterh...@aol.com
Reply-To: peterh...@aol.com
To: dmck...@gte.net, emc-p...@ieee.org
Subject: Re: Got a beef with an NRTL ...
Date: Thu, 19 Oct 2000 22:17:11 EDT


Doug,

I have used DC-DC power supply with the AC fuse on the PSU in our products
many times and have never heard such a saga from an agency. The PSU report
will certainly have C of A and in addition to that almost all test houses
when testing DC-Dc power supply which is fitted with AC fuse, they will
conduct certain abnormal tests to ensure that fuse does what it is supposed
to do and will list all the fuses that were used during the testing. In 
fact
UL PAG 1950 has one particular clause about such thing and will allow the 
PSU

manufacturer to use AC fuse on a DC-DC PSU provided certain conditions are
met.

I suggest you go back to the top management and demand that they show the
clause of the standard where it says this practice is not acceptable. If 
you

look at most fuse catalogues, you will notice that many of the fuses even
though they are rated for AC, they have also been test for DC and fuse
manufacturers would confirm this.

Don't give up and demand full explanation. It seems to me that your product
certification engineer is either have not enough experience or he is after
promotion.

Thanks
Peter

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RE: Holes, wave guides and honeycombs

[Gary McInturff]

Good question. I was just digging around for that information my self so I
am waiting with baited breath the responses, and have a question. 
The question deals more with aperture such as is found in general
computing equipment enclosure sheet metal, rather than a wave guide which
also has some significant thickness to it.

1)If there is multiple apertures doesn't the distance between each aperture
matter as well, and the distance between source and aperture significant?
Placing them too close together effectively makes them appear as a single
much larger opening, and moving the source very close to the opening
degrades the shielding effectiveness? 




-Original Message-
From: jim_bac...@mail.monarch.com [mailto:jim_bac...@mail.monarch.com]
Sent: Friday, October 20, 2000 7:31 AM
To: Paolo Roncone; emc-p...@majordomo.ieee.org
Subject: Re:Holes, waveguides and honeycombs



forwarding for pronc...@cisco.com

Reply Separator
Subject:Holes, waveguides and honeycombs
Author: Paolo Roncone 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 12:03 PM

Group,

We are working on a couple of designs of telecom gear contained in metal 
s.u.b.-racks and we have to meet emission limits up to 40 GHz.
I need some advice on the workings of waveguides below cut-off and 
honeycombs, because we have to include ventilation openings without 
possibly degrading the shielding effectiveness.
First, I made an inquiry on textbook formulas for circular and rectangular 
waveguide cut-off frequencies. I was happy to find consistency among three 
different sources (I found the same formulas although rearranged in 
different fashions).
 From Ott's "Noise reduction techniques in electronic systems" I found:

fc = [6.9/d] GHz   for circular waveguides

fc = [5.9/l] GHz  for rectangular waveguides

where fc = cutoff frequency
d = diameter of circular section (inches)
l = longer side of rectangular section (inches)

Now my question is: what about honeycomb panels ?
Can I use the same formulas for honeycombs ? Here the single cells are 
neither circular nor rectangular. Can I still apply these formulas with 
good accuracy ? If not, anyone knows of other formulas that apply in this
case?
As for attenuation (shielding effectivenes) of one single waveguide 
opening, if  the frequency is well below cutoff , this is proportional to 
the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
to 4:1 in order to get good attenuation.

Now, I just found a formula for attenuation of honeycomb panels as function 
of frequency, length-to-width ratio of each cell and also number of cells:

S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)

where:

S [dB] = Shielding Effectiveness in dB
fc = cutoff frequency of waveguide
f = frequency
t = cell length (or thickness)
W = cell section width
n = number of cells in honeycomb panel

I have no problems with the first two terms in the above equation. As for 
the third term, that means that increasing the number of cells (n) in the 
honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
1000 cells means 30 dBs lost).
Before finding this formula I had a feeling that due to the skin-effect 
each honeycomb cell could be treated as a single cell.
So far I wasn't able to find other formulas for honeycomb panels. So I'd 
like to have some feedback on this.
I hope to get some useful directions.

Thank you in advance,

Paolo Roncone
Cisco Photonics, Italy

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 Richard Nute:   ri...@ieee.org


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RE: Holes, waveguides and honeycombs

[Brumbaugh, David]

The formula for honeycomb panels agrees with the one I have found in a 
shielding design guide, provided by a commercial shielding products 
manufacturer. (If you want to know which one, contact me directly.) The last 
term in the equation is similar to that for multiple vent hole openings, where 
the thickness (depth) is much smaller than the opening. In this case, the depth 
is greater than the opening, but you still have to account for multiple 
apertures. You can't ignore it. If you think about it, each hole acts as an 
antenna source on the other side of the panel. The effect of each one 
individually may be small, but collectively, they add up. The result is 
(obviously) an overall reduction in shielding effectiveness. 
The advantage of honeycomb, or any waveguide below cutoff, is that the 
attenuation is very high below the cutoff frequency. Even with multiple 
apertures, the shielding should still be very high below the cutoff frequency.
DB

> --
> From: jim_bac...@mail.monarch.com[SMTP:jim_bac...@mail.monarch.com]
> Reply To: jim_bac...@mail.monarch.com
> Sent: Friday, October 20, 2000 7:31 AM
> To:   Paolo Roncone; emc-p...@majordomo.ieee.org
> Subject:  Re:Holes, waveguides and honeycombs
> 
> 
> forwarding for pronc...@cisco.com
> 
> Reply Separator
> Subject:Holes, waveguides and honeycombs
> Author: Paolo Roncone 
> Date:   10/20/00 12:03 PM
> 
> Group,
> 
> We are working on a couple of designs of telecom gear contained in metal 
> s.u.b.-racks and we have to meet emission limits up to 40 GHz.
> I need some advice on the workings of waveguides below cut-off and 
> honeycombs, because we have to include ventilation openings without 
> possibly degrading the shielding effectiveness.
> First, I made an inquiry on textbook formulas for circular and rectangular 
> waveguide cut-off frequencies. I was happy to find consistency among three 
> different sources (I found the same formulas although rearranged in 
> different fashions).
>  From Ott's "Noise reduction techniques in electronic systems" I found:
> 
> fc = [6.9/d] GHz   for circular waveguides
> 
> fc = [5.9/l] GHz  for rectangular waveguides
> 
> where fc = cutoff frequency
> d = diameter of circular section (inches)
> l = longer side of rectangular section (inches)
> 
> Now my question is: what about honeycomb panels ?
> Can I use the same formulas for honeycombs ? Here the single cells are 
> neither circular nor rectangular. Can I still apply these formulas with 
> good accuracy ? If not, anyone knows of other formulas that apply in this 
> case?
> As for attenuation (shielding effectivenes) of one single waveguide 
> opening, if  the frequency is well below cutoff , this is proportional to 
> the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
> to 4:1 in order to get good attenuation.
> 
> Now, I just found a formula for attenuation of honeycomb panels as function 
> of frequency, length-to-width ratio of each cell and also number of cells:
> 
> S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)
> 
> where:
> 
> S [dB] = Shielding Effectiveness in dB
> fc = cutoff frequency of waveguide
> f = frequency
> t = cell length (or thickness)
> W = cell section width
> n = number of cells in honeycomb panel
> 
> I have no problems with the first two terms in the above equation. As for 
> the third term, that means that increasing the number of cells (n) in the 
> honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
> 1000 cells means 30 dBs lost).
> Before finding this formula I had a feeling that due to the skin-effect 
> each honeycomb cell could be treated as a single cell.
> So far I wasn't able to find other formulas for honeycomb panels. So I'd 
> like to have some feedback on this.
> I hope to get some useful directions.
> 
> Thank you in advance,> 
> 
> Paolo Roncone
> Cisco Photonics, Italy
> 
> 

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RE: Automotive EMC Directive

[Chuck Seyboldt]

Dear Lothar:

I absolutely agree with the approach that you advocate,
and indeed took that approach.  This is what I learned.

VCA North America is competent to issue the certificate,
and they work with and accept the test results of an
already-approved laboratory that is in Michigan.

The approval authority *is* VCA North America, which is a
North American located firm related to VCA in the UK.

VCA North America is open to witnessing testing in other
laboratories as well, and I have the impression that any
laboratory that is well operated and well documented will be
found acceptable with little ado.

Regards,
Chuck Seyboldt
http://www.walaw.com


At 09:27 (-0700) on 00.10.20, Lothar Schmidt wrote:

> Chuck,
> 
> I am convinced that there are labs which can measure these
> things. The problem will be the approval process they have to
> go through.
> 
> My suggestion: contact first the approval authority in Europe
> which report from which lab will they accept, then decide
> which lab you'll use.
> 
> Best Regards
> 
> Lothar Schmidt
> Technical Manager EMC/Bluetooth, 
> BQB, Competent Body
> Cetecom Inc.
> 411 Dixon Landing Road
> Milpitas, CA 95035
> Phone: +1 (408) 586 6214
> Fax: +1 (408) 586 6299
> 
> 
> -Original Message-
> From: Chuck Seyboldt [mailto:cbo...@nlis.net]
> Sent: Friday, October 20, 2000 9:24 AM
> To: IEEE EMC/Product Safety (E-mail); Lothar Schmidt
> Cc: 'Ned Devine'
> Subject: RE: Automotive EMC Directive
> 
> Dear Ned (and group):
> 
>   There are laboratories in the US that perform this
> testing.  I would like to thank John Allen for his message from
> June of this year, where he pointed out VCA North America.  I
> have spoken with this company - they do not perform the test,
> they witness it and issue the certificate.  They work with a test
> laboratory in Michigan, and are willing to witness testing in
> other laboratories after they satisfy themselves that the lab is
> appropriately operated and maintained.
> 
> http://www.vca.gov.uk
> 
> VCA North America
> Livonia, Michigan
> 734 455-6352


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Re:RE: Holes, waveguides and honeycombs

[Jim Bacher]

forwarding for: 


Reply Separator
Subject:RE: Holes, waveguides and honeycombs
Author: "Brench; Colin" 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 11:35 AM

Hi,  

here are some clarifications that might help you in your design.  

Shielding effectiveness is a measure specifically geared to a plane wave,
that means the source is a long way from the shield and there is no direct
interaction between them.  This is seldom true, as a result I have found
that the shielding behavior is better than expected 99 times out of 100.

The effect of the number of holes is also a tough call.  Really this should
be read as the number of equally illuminated holes from each source rather
than the total number of holes.  Looking into this often shows that only a
small portion of the overall vent area needs to be considered for each
source.

Shielding performance goes up drastically with the thickness.  A w/t of 1:1
gives 27dB 2:1= 54 and 4:1 over 100dB "per hole".  I have designs which are
so far only required to work to around 20GHz worst case and use 2:1 (3mm
holes 6mm thick).  Probably the most common size has a 4:1 ratio.  If you
really find that you need more shielding performance then honeycomb is
available with two other constructions; The first consists of two thin
honeycombs joined together with a half cell offset, I'm not sure how this
behaves.  The second has the honeycomb at an angle of 45, so that the
thickness remains small but the honeycomb thickness is increased by 40%.
Again this can be stacked for even better performance.  However, that is
pretty extreme.

Remember that to see the benefit of high levels of shielding all your I/O
will need to be equally well filtered.

Regards,
Colin..

-Original Message-
From: jim_bac...@mail.monarch.com [mailto:jim_bac...@mail.monarch.com]
Sent: Friday, October 20, 2000 10:31 AM
To: Paolo Roncone; emc-p...@majordomo.ieee.org
Subject: Re:Holes, waveguides and honeycombs



forwarding for pronc...@cisco.com

Reply Separator
Subject:Holes, waveguides and honeycombs
Author: Paolo Roncone 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 12:03 PM

Group,

We are working on a couple of designs of telecom gear contained in metal 
s.u.b.-racks and we have to meet emission limits up to 40 GHz.
I need some advice on the workings of waveguides below cut-off and 
honeycombs, because we have to include ventilation openings without 
possibly degrading the shielding effectiveness.
First, I made an inquiry on textbook formulas for circular and rectangular 
waveguide cut-off frequencies. I was happy to find consistency among three 
different sources (I found the same formulas although rearranged in 
different fashions).
 From Ott's "Noise reduction techniques in electronic systems" I found:

fc = [6.9/d] GHz   for circular waveguides

fc = [5.9/l] GHz  for rectangular waveguides

where fc = cutoff frequency
d = diameter of circular section (inches)
l = longer side of rectangular section (inches)

Now my question is: what about honeycomb panels ?
Can I use the same formulas for honeycombs ? Here the single cells are 
neither circular nor rectangular. Can I still apply these formulas with 
good accuracy ? If not, anyone knows of other formulas that apply in this
case?
As for attenuation (shielding effectivenes) of one single waveguide 
opening, if  the frequency is well below cutoff , this is proportional to 
the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
to 4:1 in order to get good attenuation.

Now, I just found a formula for attenuation of honeycomb panels as function 
of frequency, length-to-width ratio of each cell and also number of cells:

S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)

where:

S [dB] = Shielding Effectiveness in dB
fc = cutoff frequency of waveguide
f = frequency
t = cell length (or thickness)
W = cell section width
n = number of cells in honeycomb panel

I have no problems with the first two terms in the above equation. As for 
the third term, that means that increasing the number of cells (n) in the 
honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
1000 cells means 30 dBs lost).
Before finding this formula I had a feeling that due to the skin-effect 
each honeycomb cell could be treated as a single cell.
So far I wasn't able to find other formulas for honeycomb panels. So I'd 
like to have some feedback on this.
I hope to get some useful directions.

Thank you in advance,

Paolo Roncone
Cisco Photonics, Italy

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RE: Automotive EMC Directive

[Chuck Seyboldt]

Dear Ned (and group):

There are laboratories in the US that perform this
testing.  I would like to thank John Allen for his message from
June of this year, where he pointed out VCA North America.  I
have spoken with this company - they do not perform the test,
they witness it and issue the certificate.  They work with a test
laboratory in Michigan, and are willing to witness testing in
other laboratories after they satisfy themselves that the lab is
appropriately operated and maintained.

http://www.vca.gov.uk

VCA North America
Livonia, Michigan
734 455-6352

Regards,
Chuck Seyboldt

At 10:00 (-0700) on 00.10.19, Lothar Schmidt wrote:

> I think there is no lab in the US.
> 
> You have to carefull which lab you choose. 
> 
> Reason:
> The labs are accredeted by the national authorities and at this time the
> national authorities only accept tests form lab they accredited. 
> 
> In practice if you use an accredeted Lab in Germany (e.g) CETECOM ICT
> Services in Saarbruecken http:www.cetecom.de) you have to use the Kraftfahrt
> Bundesamt (national authority) for the approval. 
> However the the approval is then valid for Europe.
> 
> 
> Best Regards
> 
> Lothar Schmidt
> Technical Manager EMC/Bluetooth, 
> BQB, Competent Body
> Cetecom Inc.
> 411 Dixon Landing Road
> Milpitas, CA 95035
> Phone: +1 (408) 586 6214
> Fax:   +1 (408) 586 6299
> 
> 
> -Original Message-
> From: Ned Devine [mailto:ndev...@entela.com]
> Sent: Thursday, October 19, 2000 5:55 AM
> To: IEEE EMC/Product Safety (E-mail)
> Subject: Automotive EMC Directive 
> 
> Hi,
> 
> I have been volunteered to research the Automotive EMC Directive.  What I
> have found so far is,
> 
> - The directive is 95/54/EC which is an amendment to 72/245/EEC.
> 
> - The directive is an "old approach" and has all of the necessary test
> procedures and methods in the directive.
> 
> - Self declaration is not allowed.  You need a "technical service" to
> approve your unit.
> 
> - The mark is the "e" mark and not the CE marking.
> 
> - The effective date is 01 October 2002.
> 
> - The tests listed in the directive are radiated broadband emissions,
> radiated narrowband emissions and radiated immunity.
> 
> 
> The questions I have are.
> 
> - Is what I have above correct?
> 
> - How do I get a copy of the directive(s)?
> 
> - Does anyone have a list of the "technical services", or know where I
> can get one?
> 
> - Does anyone have a sample of the "e" mark, or know where I can get
> one?
> 
> - Are there any labs in the USA that do this type of testing? 
> 
> 
> Thanks
> 
> Ned Devine
> Entela, Inc.
> 3033 Madison Ave. S.E.
> Grand Rapids, MI  49548
> Program Manager III
> Phone 616 248 9671
> Fax  616 574 9752
> e-mail  ndev...@entela.com 


---
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RE: Automotive EMC Directive

[Lothar Schmidt]

Chuck,

I am convinced that there are labs which can measure these things. The
problem will be the approval process they have to go through.

My suggestion: contact first the approval authority in Europe which report
from which lab will they accept, then decide which lab you'll use.

Best Regards

Lothar Schmidt
Technical Manager EMC/Bluetooth, 
BQB, Competent Body
Cetecom Inc.
411 Dixon Landing Road
Milpitas, CA 95035
Phone: +1 (408) 586 6214
Fax: +1 (408) 586 6299


-Original Message-
From: Chuck Seyboldt [mailto:cbo...@nlis.net]
Sent: Friday, October 20, 2000 9:24 AM
To: IEEE EMC/Product Safety (E-mail); Lothar Schmidt
Cc: 'Ned Devine'
Subject: RE: Automotive EMC Directive



Dear Ned (and group):

There are laboratories in the US that perform this
testing.  I would like to thank John Allen for his message from
June of this year, where he pointed out VCA North America.  I
have spoken with this company - they do not perform the test,
they witness it and issue the certificate.  They work with a test
laboratory in Michigan, and are willing to witness testing in
other laboratories after they satisfy themselves that the lab is
appropriately operated and maintained.

http://www.vca.gov.uk

VCA North America
Livonia, Michigan
734 455-6352

Regards,
Chuck Seyboldt

At 10:00 (-0700) on 00.10.19, Lothar Schmidt wrote:

> I think there is no lab in the US.
> 
> You have to carefull which lab you choose. 
> 
> Reason:
> The labs are accredeted by the national authorities and at this time the
> national authorities only accept tests form lab they accredited. 
> 
> In practice if you use an accredeted Lab in Germany (e.g) CETECOM ICT
> Services in Saarbruecken http:www.cetecom.de) you have to use the
Kraftfahrt
> Bundesamt (national authority) for the approval. 
> However the the approval is then valid for Europe.
> 
> 
> Best Regards
> 
> Lothar Schmidt
> Technical Manager EMC/Bluetooth, 
> BQB, Competent Body
> Cetecom Inc.
> 411 Dixon Landing Road
> Milpitas, CA 95035
> Phone: +1 (408) 586 6214
> Fax:   +1 (408) 586 6299
> 
> 
> -Original Message-
> From: Ned Devine [mailto:ndev...@entela.com]
> Sent: Thursday, October 19, 2000 5:55 AM
> To: IEEE EMC/Product Safety (E-mail)
> Subject: Automotive EMC Directive 
> 
> Hi,
> 
> I have been volunteered to research the Automotive EMC Directive.  What I
> have found so far is,
> 
> - The directive is 95/54/EC which is an amendment to 72/245/EEC.
> 
> - The directive is an "old approach" and has all of the necessary test
> procedures and methods in the directive.
> 
> - Self declaration is not allowed.  You need a "technical service" to
> approve your unit.
> 
> - The mark is the "e" mark and not the CE marking.
> 
> - The effective date is 01 October 2002.
> 
> - The tests listed in the directive are radiated broadband emissions,
> radiated narrowband emissions and radiated immunity.
> 
> 
> The questions I have are.
> 
> - Is what I have above correct?
> 
> - How do I get a copy of the directive(s)?
> 
> - Does anyone have a list of the "technical services", or know where I
> can get one?
> 
> - Does anyone have a sample of the "e" mark, or know where I can get
> one?
> 
> - Are there any labs in the USA that do this type of testing? 
> 
> 
> Thanks
> 
> Ned Devine
> Entela, Inc.
> 3033 Madison Ave. S.E.
> Grand Rapids, MI  49548
> Program Manager III
> Phone 616 248 9671
> Fax  616 574 9752
> e-mail  ndev...@entela.com 

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SAR Measurements

[Lothar Schmidt]

Hi group,
 
Does anybody know a source where is written that a portable device (spread
spectrum in the 24 gHz range) under OET 65 has not to be measured regarding
SAR if the radiated power is less than 1 mW (0 dBm)?
Or is this only the experience that these kind of devices never exeed the
limits of table 2?
 
Any hint welcome
 
Thanks

Best Regards 

Lothar Schmidt 
Technical Manager EMC/Bluetooth, 
BQB, Competent Body 
Cetecom Inc. 
411 Dixon Landing Road 
Milpitas, CA 95035 
Phone: +1 (408) 586 6214 
Fax: +1 (408) 586 6299 

 

RE: Holes, waveguides and honeycombs

[Dick Grobner]

My knowledge is limited in this area, but try contacting Tech-Etch, Plymouth
MA - USA http://www.tech-etch.com They supply (manufacturer?) honeycome
filter panels. Hope this helps.

-Original Message-
From: jim_bac...@mail.monarch.com [mailto:jim_bac...@mail.monarch.com]
Sent: Friday, October 20, 2000 9:31 AM
To: Paolo Roncone; emc-p...@majordomo.ieee.org
Subject: Re:Holes, waveguides and honeycombs



forwarding for pronc...@cisco.com

Reply Separator
Subject:Holes, waveguides and honeycombs
Author: Paolo Roncone 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 12:03 PM

Group,

We are working on a couple of designs of telecom gear contained in metal 
s.u.b.-racks and we have to meet emission limits up to 40 GHz.
I need some advice on the workings of waveguides below cut-off and 
honeycombs, because we have to include ventilation openings without 
possibly degrading the shielding effectiveness.
First, I made an inquiry on textbook formulas for circular and rectangular 
waveguide cut-off frequencies. I was happy to find consistency among three 
different sources (I found the same formulas although rearranged in 
different fashions).
 From Ott's "Noise reduction techniques in electronic systems" I found:

fc = [6.9/d] GHz   for circular waveguides

fc = [5.9/l] GHz  for rectangular waveguides

where fc = cutoff frequency
d = diameter of circular section (inches)
l = longer side of rectangular section (inches)

Now my question is: what about honeycomb panels ?
Can I use the same formulas for honeycombs ? Here the single cells are 
neither circular nor rectangular. Can I still apply these formulas with 
good accuracy ? If not, anyone knows of other formulas that apply in this
case?
As for attenuation (shielding effectivenes) of one single waveguide 
opening, if  the frequency is well below cutoff , this is proportional to 
the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
to 4:1 in order to get good attenuation.

Now, I just found a formula for attenuation of honeycomb panels as function 
of frequency, length-to-width ratio of each cell and also number of cells:

S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)

where:

S [dB] = Shielding Effectiveness in dB
fc = cutoff frequency of waveguide
f = frequency
t = cell length (or thickness)
W = cell section width
n = number of cells in honeycomb panel

I have no problems with the first two terms in the above equation. As for 
the third term, that means that increasing the number of cells (n) in the 
honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
1000 cells means 30 dBs lost).
Before finding this formula I had a feeling that due to the skin-effect 
each honeycomb cell could be treated as a single cell.
So far I wasn't able to find other formulas for honeycomb panels. So I'd 
like to have some feedback on this.
I hope to get some useful directions.

Thank you in advance,

Paolo Roncone
Cisco Photonics, Italy

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---
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Virus

[Pryor McGinnis]

If you receive an email with subject "US PRESIDENT AND FBI SECRETS" 
DO NOT OPEN IT!  IT IS A VIRUS 
It will overwrite files with extensions .vbs,.vbe,  .js,.jes,.css,.wsh, 
.sct,.jpg,.jpeg,.mp3, and .mp2.

Best Regards,
Pryor McGinnis
c...@prodigy.net 
www.ctl-lab.com

RE: Holes, waveguides and honeycombs

[William D'Orazio]

Jim,
You might want to look at "Electromagnetic Shielding Material and
Performance" by Donald R.J. White.  All of chapter contains references
related to shielding.

Best Regards,

William D'Orazio
CAE Electronics Ltd.
Electrical System Designer

Phone: (514) 341-2000 (X4555)
Fax: (514)340-5552
Email: dora...@cae.ca


-Original Message-
From: jim_bac...@mail.monarch.com [mailto:jim_bac...@mail.monarch.com]
Sent: Friday, October 20, 2000 10:31 AM
To: Paolo Roncone; emc-p...@majordomo.ieee.org
Subject: Re:Holes, waveguides and honeycombs



forwarding for pronc...@cisco.com

Reply Separator
Subject:Holes, waveguides and honeycombs
Author: Paolo Roncone 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 12:03 PM

Group,

We are working on a couple of designs of telecom gear contained in metal 
s.u.b.-racks and we have to meet emission limits up to 40 GHz.
I need some advice on the workings of waveguides below cut-off and 
honeycombs, because we have to include ventilation openings without 
possibly degrading the shielding effectiveness.
First, I made an inquiry on textbook formulas for circular and rectangular 
waveguide cut-off frequencies. I was happy to find consistency among three 
different sources (I found the same formulas although rearranged in 
different fashions).
 From Ott's "Noise reduction techniques in electronic systems" I found:

fc = [6.9/d] GHz   for circular waveguides

fc = [5.9/l] GHz  for rectangular waveguides

where fc = cutoff frequency
d = diameter of circular section (inches)
l = longer side of rectangular section (inches)

Now my question is: what about honeycomb panels ?
Can I use the same formulas for honeycombs ? Here the single cells are 
neither circular nor rectangular. Can I still apply these formulas with 
good accuracy ? If not, anyone knows of other formulas that apply in this
case?
As for attenuation (shielding effectivenes) of one single waveguide 
opening, if  the frequency is well below cutoff , this is proportional to 
the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
to 4:1 in order to get good attenuation.

Now, I just found a formula for attenuation of honeycomb panels as function 
of frequency, length-to-width ratio of each cell and also number of cells:

S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)

where:

S [dB] = Shielding Effectiveness in dB
fc = cutoff frequency of waveguide
f = frequency
t = cell length (or thickness)
W = cell section width
n = number of cells in honeycomb panel

I have no problems with the first two terms in the above equation. As for 
the third term, that means that increasing the number of cells (n) in the 
honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
1000 cells means 30 dBs lost).
Before finding this formula I had a feeling that due to the skin-effect 
each honeycomb cell could be treated as a single cell.
So far I wasn't able to find other formulas for honeycomb panels. So I'd 
like to have some feedback on this.
I hope to get some useful directions.

Thank you in advance,

Paolo Roncone
Cisco Photonics, Italy

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For policy questions, send mail to:
 Richard Nute:   ri...@ieee.org

Re: Holes, waveguides and honeycombs

[Lfresearch]

Paolo,

in addition to using honeycomb, you could also add an extension to the 
cooling vent. A bend, with some Fe absorber in the region of the bend is 
particularly effective

Best regards,

Derek.

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FW: Majordomo results

[George Sparacino]

Hello out there..

I've been trying to unsubscribe from the list.. Seems that majordomo won't
let me go... Can anyone out there help ?  I am using the prescribed syntax
but keep getting the folowing message..  Then when I trey to contact
majordomo "owner" I get the second message below..

Sorry to bother everyone with this and thanks in advance for your help.
George


-Original Message-
From: majord...@ieee.org [mailto:majord...@ieee.org] 
Sent: Friday, October 20, 2000 8:55 AM
To: george.sparac...@bostonacoustics.com
Subject: Majordomo results
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The MTS-ID of the original message is:
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Re:Holes, waveguides and honeycombs

[Jim Bacher]

forwarding for pronc...@cisco.com

Reply Separator
Subject:Holes, waveguides and honeycombs
Author: Paolo Roncone 
List-Post: emc-pstc@listserv.ieee.org
Date:   10/20/00 12:03 PM

Group,

We are working on a couple of designs of telecom gear contained in metal 
s.u.b.-racks and we have to meet emission limits up to 40 GHz.
I need some advice on the workings of waveguides below cut-off and 
honeycombs, because we have to include ventilation openings without 
possibly degrading the shielding effectiveness.
First, I made an inquiry on textbook formulas for circular and rectangular 
waveguide cut-off frequencies. I was happy to find consistency among three 
different sources (I found the same formulas although rearranged in 
different fashions).
 From Ott's "Noise reduction techniques in electronic systems" I found:

fc = [6.9/d] GHz   for circular waveguides

fc = [5.9/l] GHz  for rectangular waveguides

where fc = cutoff frequency
d = diameter of circular section (inches)
l = longer side of rectangular section (inches)

Now my question is: what about honeycomb panels ?
Can I use the same formulas for honeycombs ? Here the single cells are 
neither circular nor rectangular. Can I still apply these formulas with 
good accuracy ? If not, anyone knows of other formulas that apply in this case?
As for attenuation (shielding effectivenes) of one single waveguide 
opening, if  the frequency is well below cutoff , this is proportional to 
the ratio of length/diameter of the waveguide. The recommended ratio is 2:1 
to 4:1 in order to get good attenuation.

Now, I just found a formula for attenuation of honeycomb panels as function 
of frequency, length-to-width ratio of each cell and also number of cells:

S [dB]  = 20log(fc/f) + 27.3(t/W) - 10log(n)(f < fc/10)

where:

S [dB] = Shielding Effectiveness in dB
fc = cutoff frequency of waveguide
f = frequency
t = cell length (or thickness)
W = cell section width
n = number of cells in honeycomb panel

I have no problems with the first two terms in the above equation. As for 
the third term, that means that increasing the number of cells (n) in the 
honeycomb panel degrades the shielding effectiveness of  the panel (ex. 
1000 cells means 30 dBs lost).
Before finding this formula I had a feeling that due to the skin-effect 
each honeycomb cell could be treated as a single cell.
So far I wasn't able to find other formulas for honeycomb panels. So I'd 
like to have some feedback on this.
I hope to get some useful directions.

Thank you in advance,

Paolo Roncone
Cisco Photonics, Italy

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RE: EN55022 vrs. FCC Part 15

[Colgan, Chris]

Of course it does.  I had a bad case of pressing the send button without the
brain being engaged.  Sorry for the duff information.

Chris

> -Original Message-
> From: jmur...@quantumbridge.com [SMTP:jmur...@quantumbridge.com]
> Sent: 19 October 2000 20:13
> To:   emc-p...@majordomo.ieee.org
> Subject:  RE: EN55022 vrs. FCC Part 15
> 
> 
> FCC Pt15 states that you can use their limits or, alternatively, the
> limits
> found in CISPR 22:1995.  Your EN Class B data should be sufficient for
> having your lab generate an FCC B (or A) report.
> 
> Jack
> 
> -Original Message-
> From: Colgan, Chris [mailto:chris.col...@tagmclarenaudio.com]
> Sent: Thursday, October 19, 2000 4:51 AM
> To: 'Emc-Pstc' (E-mail)
> Subject: RE: EN55022 vrs. FCC Part 15
> 
> 
> 
> No.
> The class B FCC limits for conducted disturbance at the mains ports are
> lower than EN55022 class B.
> QP limits:
> FCC - 0.45 to 30MHz = 48dBuV
> EN - 0.15 to 0.5MHz = 66 to 56dBuV (decreasing linearly with the log of
> frequency)
>0.5 to 5MHz = 56dBuV
>5 to 30MHz = 60dBuV
> Radiated disturbance is performed at 3m for FCC and 10m for EN55022.  The
> limits and are different.
> QP limits:
> FCC @ 3m - 30 to 88MHz = 34dBuV/m
>88 to 216MHz = 37.5dBuV/m
>216 to 960MHz = 40dBuV/m
>960 to 1000MHz = 48dBuV/m
> EN @ 10m - 30 to 230MHz = 30dBuV/m
>230 to 1000MHz = 37dBuV/m
> 
> I'm afraid the only way to compare the two standards is to buy copies of
> them.
> 
> Chris Colgan
> EMC & Safety
> > TAG McLaren Audio Ltd
> The Summit, Latham Road
> Huntingdon, Cambs, PE29 6ZU
> United Kingdom
> > * Phone: +44 (0)1480 415627
> > * Fax: +44 (0)1480 415689
> > * Mailto:chris.col...@tagmclarenaudio.com
> > * http://www.tagmclarenaudio.com
> > 
> > 
> > 
> > -Original Message-
> > From:   Keith Zell [SMTP:zell...@pmifeg.com]
> > Sent:   18 October 2000 14:53
> > To: emc-p...@majordomo.ieee.org
> > Subject:EN55022 vrs. FCC Part 15
> > 
> > 
> > Will a product certified to EN55022 class B necessarily comply to FCC
> Part
> > 15 Class A limits?  Where might I find a valid comparison of these two
> EMC
> > standards. 
> > 
> > As always, thanks for your help. 
> > 
> > B. Keith Zell
> > Electrical Design Engineer
> > PMI Food Equipment Group
> > Troy, OH 45374
> > (937) 332-3067 (ph)
> > (937) 332-3007 (fax)
> > zell...@pmifeg.com
> 
> 
> **  
>Please visit us at www.tagmclarenaudio.com
> **
> 
> The contents of this E-mail are confidential and for the exclusive
> use of the intended recipient. If you receive this E-mail in error,
> please delete it from your system immediately and notify us either
> by E-mail, telephone or fax. You  should not  copy, forward or 
> otherwise disclose the content of the E-mail.
> 
> TAG McLaren Audio Ltd
> The Summit, 11 Latham Road
> Huntingdon, Cambs, PE29 6ZU
> Telephone : 01480 415600 (+44 1480 415600)
> Facsimile : 01480 52159 (+44 1480 52159)
> 
> **  
>Please visit us at www.tagmclarenaudio.com
> **
> 
> ---
> This message is from the IEEE EMC Society Product Safety
> Technical Committee emc-pstc discussion list.
> 
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> 
> ---
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**  
   Please visit us at www.tagmclarenaudio.com
**

The contents of this E-mail are confidential and for the exclusive
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please delete it from your system immediately and notify us either
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TAG McLaren Audio Ltd
The Summit, 11 Latham Road
Huntingdon, Cambs, PE29 6ZU
Telephone 

Re: Got a beef with an NRTL ...

[mike harris]

Hi Doug,

I believe there is another option (which may or may not be palatable) - You
can ask your NRTL to strap out (bypass) the fuse and conduct whatever tests
they like & if there is no fire or shock danger they must ignore the fuse
rating entirely. The down side of this is the cost & time of the additional
testing.

Mike Harris/Teccom

-Original Message-
From: Doug 
To: EMC-PSTC Discussion Group 
List-Post: emc-pstc@listserv.ieee.org
Date: Thursday, October 19, 2000 10:50 AM
Subject: Got a beef with an NRTL ...


>
>I'm just about ready to escalate this issue.
>
>Issue:  Major NRTL has recognized a DC-DC power supply.
>Said ps is being used within the confines of
>it's stated purpose, input power, output power,
>temps, etc ...
>
>Said product is submitted to NRTL for what appeared
>to be a walk through.  Oh no, Mr. McKean.  You can't
>use THAT power supply as intended.  Input fuse of
>power supply (that is the fuse INSIDE the power that
>is out of our hands) is an AC fuse.  It should be a
>DC fuse.  (From the documentation from the ps mfr,
>the approval was done with the aC rated fuse.)
>
>You have to either:
>
>1. have the ps mfr change the input fuse.
>
>or
>
>2. drop an in-line fuse between the power inlet
>   of the product and the input of the ps.
>
>EXCUSE ME!?!
>
>How the heck can a power supply mfr get NRTL approval on one
>hand and, yet, when that power supply is used within it's
>intended and stated purpose, get rejected?
>
>Even bringing this to the attention of the test engineer
>(who has approx over 10 years experience as a test eng)
>it defaults to - "well, that's just because the OTHER
>test engineer interpreted it that way ... "
>
>I can understand and have been in those areas of
>"interpretation" with NRTLs, but this one really ...
>er ... surprises me.
>
>Yours truly and totally confused, Doug
>
>---
>This message is from the IEEE EMC Society Product Safety
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Re: Surge testing.

[Peter Poulos]

IEEE C62.41-1991 has some good background information on rates and severity 
of power surges - graphs for surge peak vs rate of occurrence etc.




At 09:34 AM 20/10/2000, Cameron O'phee wrote:


Hi all,

I would like to know if anyone could point me to any articles or studies of
real world mains born interference that substantiate the need to test
equipment for immunity to these phenomena.  I want to convince an engineer
from another company that the standards my company has chosen to adopt are
not excessive.

Regards,

Cameron O'Phee.
EMC & Safety Precompliance.
Aristocrat Technologies Australia.

Telephone : +61 2 9697 4420
Facsimile  : +61 2 9663 1412
Mobile  :   0418 464 016

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Re: Got a beef with an NRTL ...

[Peterhays]

Doug,

I have used DC-DC power supply with the AC fuse on the PSU in our products 
many times and have never heard such a saga from an agency. The PSU report 
will certainly have C of A and in addition to that almost all test houses 
when testing DC-Dc power supply which is fitted with AC fuse, they will 
conduct certain abnormal tests to ensure that fuse does what it is supposed 
to do and will list all the fuses that were used during the testing. In fact 
UL PAG 1950 has one particular clause about such thing and will allow the PSU 
manufacturer to use AC fuse on a DC-DC PSU provided certain conditions are 
met.

I suggest you go back to the top management and demand that they show the 
clause of the standard where it says this practice is not acceptable. If you 
look at most fuse catalogues, you will notice that many of the fuses even 
though they are rated for AC, they have also been test for DC and fuse 
manufacturers would confirm this.

Don't give up and demand full explanation. It seems to me that your product 
certification engineer is either have not enough experience or he is after 
promotion.

Thanks
Peter

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RE: EN55022 vrs. FCC Part 15

[Benoit Nadeau]

Bonjour de Montréal,

This is true, but don't forget that if your product uses or generate 
frequencies over 108 MHz you will have to test over 1 GHz using the ANSI 
C63.4 Standard and Part 15 limits. The FCC limit can go up to 40 GHz 
according to the following table:


9 KHz to  1,705 MHz /   30 MHz
1,705 to 108 MHz /  1 GHz
108 to 500 MHz /2 GHz
500 to 1000 MHz/5 GHz
> 1 GHz /   5th harmonic up to 40 GHz

Best regards,



At 03:13 PM 10/19/2000 -0400, jmur...@quantumbridge.com wrote:


FCC Pt15 states that you can use their limits or, alternatively, the limits
found in CISPR 22:1995.  Your EN Class B data should be sufficient for
having your lab generate an FCC B (or A) report.

Jack

-Original Message-
From: Colgan, Chris [mailto:chris.col...@tagmclarenaudio.com]
Sent: Thursday, October 19, 2000 4:51 AM
To: 'Emc-Pstc' (E-mail)
Subject: RE: EN55022 vrs. FCC Part 15



No.
The class B FCC limits for conducted disturbance at the mains ports are
lower than EN55022 class B.
QP limits:
FCC - 0.45 to 30MHz = 48dBuV
EN - 0.15 to 0.5MHz = 66 to 56dBuV (decreasing linearly with the log of
frequency)
   0.5 to 5MHz = 56dBuV
   5 to 30MHz = 60dBuV
Radiated disturbance is performed at 3m for FCC and 10m for EN55022.  The
limits and are different.
QP limits:
FCC @ 3m - 30 to 88MHz = 34dBuV/m
   88 to 216MHz = 37.5dBuV/m
   216 to 960MHz = 40dBuV/m
   960 to 1000MHz = 48dBuV/m
EN @ 10m - 30 to 230MHz = 30dBuV/m
   230 to 1000MHz = 37dBuV/m

I'm afraid the only way to compare the two standards is to buy copies of
them.

Chris Colgan
EMC & Safety
> TAG McLaren Audio Ltd
The Summit, Latham Road
Huntingdon, Cambs, PE29 6ZU
United Kingdom
> * Phone: +44 (0)1480 415627
> * Fax: +44 (0)1480 415689
> * Mailto:chris.col...@tagmclarenaudio.com
> * http://www.tagmclarenaudio.com
>
>
>
> -Original Message-
> From: Keith Zell [SMTP:zell...@pmifeg.com]
> Sent: 18 October 2000 14:53
> To:   emc-p...@majordomo.ieee.org
> Subject:  EN55022 vrs. FCC Part 15
>
>
> Will a product certified to EN55022 class B necessarily comply to FCC Part
> 15 Class A limits?  Where might I find a valid comparison of these two EMC
> standards.
>
> As always, thanks for your help.
>
> B. Keith Zell
> Electrical Design Engineer
> PMI Food Equipment Group
> Troy, OH 45374
> (937) 332-3067 (ph)
> (937) 332-3007 (fax)
> zell...@pmifeg.com


**
   Please visit us at www.tagmclarenaudio.com
**

The contents of this E-mail are confidential and for the exclusive
use of the intended recipient. If you receive this E-mail in error,
please delete it from your system immediately and notify us either
by E-mail, telephone or fax. You  should not  copy, forward or
otherwise disclose the content of the E-mail.

TAG McLaren Audio Ltd
The Summit, 11 Latham Road
Huntingdon, Cambs, PE29 6ZU
Telephone : 01480 415600 (+44 1480 415600)
Facsimile : 01480 52159 (+44 1480 52159)

**
   Please visit us at www.tagmclarenaudio.com
**

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--
Benoit Nadeau, ing. M.ing. (P.Eng., M.Eng)
Gerant du Groupe Conformite (Conformity Group Manager)
Matrox 
--

1055, boul. St-Regis
Dorval (Quebec) Canada
H9P 2T4

Tel : (1)(514) 822-6000 (x2475)
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