[TriEmbed] Does my Raspberry Pi LoRa modem board look ready to send off to OSHPark?

[Scott Hall]

*As everyone responds, please include Adam (Adam Novak <interfect at gmail.com
<interfect at gmail.com>>) in your "To:" addressing -- I don't think he is a
member of the TriEmbed email list yet.*

On Fri, Oct 29, 2021 at 12:05 PM John Wettroth <jwet at mindspring.com> wrote:

> The microstrip track with all the via fencing looks too narrow.  I assume
> this is supposed to be a 50 ohm line?  You might check this- I assume
> this is on FR4 at 1.5 mm (.062”), if so, a 50 ohm track is about 3 mm wide
> (.125”).  A narrower track will give you a higher impedance line, this
> line looks more like a 100 ohm line.  If it’s a matching section, ignore
> my comment, but if its supposed to be 50 ohms, check it.  You might also
> consider putting some via stitches around the perimeter of the planes-
> they’re kind of floating RF wise at the edges except perhaps at the top and
> at the fencing.  I’m sure your initial design will work as is- but the
> narrow track will create some mismatch loss (range) and the lack of
> perimeter stitching can cause RF leakage- kind of a slot antenna that will
> radiate in the plane of the board- could give a squirrelly radiation
> pattern.  If the module vendor has a recommended layout, I would study it
> carefully and use it as much as possible.  Also, is any local bypassing
> recommended external to the module on power lines, etc.?  Something like
> a 10 nF 0805 and a bulk 1 uF ceramic would seem wise and cheap.  That
> 3.3v line is an inductor- not so bad really but dying to have a shunt C at
> the module end to make a proper “bias T” kind of structure.  Have fun.
>
>
>
> Regards,
> John M. Wettroth
> (984) 329-5420 (home)
> (919) 349-9875 (cell)
>
> *From:* TriEmbed <triembed-bounces at triembed.org> *On Behalf Of *Scott
> Hall via TriEmbed
> *Sent:* Friday, October 29, 2021 3:35 AM
> *To:* Triangle Embedded Computing Interest Group <triembed at triembed.org>
> *Cc:* Adam Novak <interfect at gmail.com>
> *Subject:* [TriEmbed] Does my Raspberry Pi LoRa modem board look ready to
> send off to OSHPark?
>
>
>
> Question from Adam Novak <interfect at gmail.com>, posed at 9:26pm 28-Oct-21:
>
> Anybody here know PCB design? Does my Raspberry Pi LoRa modem board look
> ready to send off to OSHPark?
>
>
>


-- 
Scott G. Hall
Raleigh, NC, USA
scottghall1 at gmail.com
*Although kindness is rarely a job, no matter what you do it's always an
option.*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.triembed.org/pipermail/triembed_triembed.org/attachments/20211029/969d880e/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 33381 bytes
Desc: not available
URL: <http://mail.triembed.org/pipermail/triembed_triembed.org/attachments/20211029/969d880e/attachment.jpg>