Re: Utility of copper pours on four-layer boards

On Mon, 7 Apr 2008 13:07:52 -0700, "Joel Koltner"
<zapwireDASHgroups@xxxxxxxxx> wrote:

"John Larkin" <jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:nutkv353jttdl8o4s9ups03b7htfn5gasm@xxxxxxxxxx
I disagree that it's "common practice." I rarely see this, and never
do it.

Perhaps it should be, "not uncommon?" Anyway, thanks for the comments -- I
respect your design capabilities John and it's clear you have a good mind for
what works and what doesn't. (I probably spent too long in school as I seem
to often be overly conservative when it comes to such matters. Although I'm
not as bad as one professor I had for a microwaves class where who was
cautioning a student who'd designed a ~3GHz stripline filter that moving his
input or output SMA connectors even a millimeter off-center from the
microstrip would "very significantly" affect the board's response... :-( )

---Joel


Crazy... a professor who can't compute a wavelength.

At 3 GHz, BNC connectors still work.

I just did a 4-layer FR4 board, and included a test trace: thru-hole
SMA, 50 ohm traces on layers 1, 3, and 4 (2 is ground), then another
SMA. I included a couple of sharp right angles and a beveled corner.
All the bends are invisible on 20 GHz TDR. The vias do show up, but
not real bad.

John

.