Not a simple rule for design, just one to alert me when speeds get fast
enough I have to pay more attention. As you should know, I am not one
for simple rules. As a famous person at Bell Labs said "Rules are no
substitute for intellegence." I would have to say that for simulations
too.
Doug
On Tue, 5 Jul 2016 16:40:36 -0700, Lee Ritchey
<leeritchey@xxxxxxxxxxxxx> wrote:
AH! The quest for simple rules!
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Smith
Sent: Tuesday, July 5, 2016 2:37 PM
To: si-list@xxxxxxxxxxxxx; Jeff Loyer <jeff.loyer@xxxxxxxxxx>
Subject: [SI-LIST] Re: Via fence along board edge
Hi Jeff,
Thanks, yes that is different. Seems like the far field radiation is
what is important here. Just looking for a simple rule that will
trigger when our designs get near a danger zone for edge radiation.
Doug
On Tue, 5 Jul 2016 14:26:56 -0700, Jeff Loyer <jeff.loyer@xxxxxxxxxx> wrote:
Hi Doug,
You might note that Franz uses a near-field probe which will be >sensitive to a different phenomenon than what you're referring to.
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Smith
Jeff Loyer
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx >
Sent: Tuesday, July 5, 2016 2:22 PMfrequency. > Thanks. >
To: curtmcn@xxxxxxxxx; si-list@xxxxxxxxxxxxx; LeeRitchey; Grasso, > Charles
Subject: [SI-LIST] Re: Via fence along board edge
Hi Chas,
That seems to indicate problems well under the waveguide cutoff
DougLee > > Ritchey
On Tue, 5 Jul 2016 21:17:58 +0000, "Grasso, Charles"
<Charles.Grasso@xxxxxxxxxxxx> wrote:
Hah - at last! Simple language for the "restofus". :-)
Doug - Franz Gisins paper shows resonances well below 500GHz!!
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042974@xxxxxxxxx
(e) charles.grasso@xxxxxxxxxxxx
(e2) chasgrasso@xxxxxxxxx
-----Original Message-----
From: Doug Smith [mailto:doug@xxxxxxxxxx] Sent: Tuesday, July 05,
2016 3:07 PM
To: Grasso, Charles; curtmcn@xxxxxxxxx; si-list@xxxxxxxxxxxxx;
want > > to show that an open side of a PCB is much like an open waveSubject: RE: [SI-LIST] Re: Via fence along board edge
Hi Lee,
It does not matter if the problem is made up. In this case, I
guide, > > but the the dimensions are so small that the interesting
frequencies > > are high enough as not to be a problem. This puts the
argument about > > PCBs into very simple language and that satisfies
engineering curiosity.
overall > > principle, which is what I am getting at.Citing lots of data does not lead to an understanding of the
assumptions on the dimensions, I get frequencies over 500 GHz where >So, I think the two cases are the same and was looking for your >insight. I have done the calculations, and making reasonable > >
edge radiation as from a waveguide would happen! Just wondering ifI > > did this correctly. Doug
<leeritchey@xxxxxxxxxxxxx> wrote:
On Tue, 5 Jul 2016 13:56:08 -0700, Lee Ritchey > >
imaginary > > problem. >This seems to me to be another case of trying to solve an
problem > > actually > exists before I attempt to solve it.As a side comment on my posts and the responses to them, I oftensay > that I am from Missouri, and need to be shown that a
EMI > > from > energy leaking out the edges and none of them have hadof > more than 3000 PCBs, I have not yet seen one of them fail
In almost 50 years of engineering and participating in the design
via > > fences or > recessing to the 20h rule. So if the problem
really > > exists, the person > making the claim owes an example of a
failure > > due to the absence of > via fences.
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Smith
There is a challenge for you! -----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx > > >
on > > > > EMISent: Tuesday, July 5, 2016 1:32 PMsi-list@xxxxxxxxxxxxx; Lee Ritchey <leeritchey@xxxxxxxxxxxxx>
To: Charles.Grasso@xxxxxxxxxxxx; curtmcn@xxxxxxxxx; >
Subject: [SI-LIST] Re: Via fence along board edgewavelength > (at some very high
Lee, a question. If the spacing between two planes was 1/2
frequency) would not the edge of the board be a little like anfew > years. Doug
open waveguide? Probably not a practical case, at least not for
another
<leeritchey@xxxxxxxxxxxxx> wrote:
On Tue, 5 Jul 2016 11:39:53 -0700, Lee Ritchey >
I think I have traced this myth to its origin. It is no more orless > than a
does > > not "leak out" the sides of a PCB to begin with. One ofmyth. >
The following papers all show with laboratory testing that EMI
them even >
shows that with or without these "grounding vias" the results arethe > same. > > > >
on > > Electromagnetic Radiation From Printed Circuit Boards", UCBrooks, Douglas. "90 Degree Corners, The Final Turn." PrintedCircuit > Design. January 1998
Fang, Jiayuan, et.al., "Effects of 20-H Rule and Shielding Vias
Santa
Cruz, > Publishing date unknown. > >
Chen, Huabo, et.al., "Effects of 20H Rule and Shielding Vias
if > > > > there will be an interference problem or not then a viain > PCBs", UC Santa Cruz EE Department, May 2001. > >
Hope this helps. >[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Grasso, Charles
Lee Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx >
Sent: Tuesday, July 5, 2016 9:21 AMdon't have a simulation tool or handy dandy formula to "guess"
To: curtmcn@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Via fence along board edge
If there is a concern about cavity resonances causing EMI and
you
fence is > > > a
Subject > > > > >outsidegood way to sleep at night! (Just count vias instead of sheep >..one..two...three...zzzzzzz)
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Curt McNamara
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042974@xxxxxxxxx
(e) charles.grasso@xxxxxxxxxxxx
(e2) chasgrasso@xxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx >
Sent: Tuesday, July 05, 2016 6:51 AMwaves
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Via fence along board edge
I have seen this done, and understand the desire to trap EM >
inside the PCB. > > There are parts and short traces on the > >
layers, with ground
pours. > The next layer in is ground on both top and bottom. >
Will the ground fence always help with EMC?will > come out any opening it can find?
- Or sometimes help because that energy has to go somewhere and
wavelength?
- Or mostly help because those openings are small compared to
the
Curt
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