*As everyone responds, please include Adam (Adam Novak <[email protected] <[email protected]>>) 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 <[email protected]> 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 <[email protected]> *On Behalf Of *Scott > Hall via TriEmbed > *Sent:* Friday, October 29, 2021 3:35 AM > *To:* Triangle Embedded Computing Interest Group <[email protected]> > *Cc:* Adam Novak <[email protected]> > *Subject:* [TriEmbed] Does my Raspberry Pi LoRa modem board look ready to > send off to OSHPark? > > > > Question from Adam Novak <[email protected]>, 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 [email protected] *Although kindness is rarely a job, no matter what you do it's always an option.*
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