In article , starman
wrote:

Pete KE9OA wrote:

I usually go for less than one tenth of a wavelength for maximum spacing
between vias. I never lay out the vias on a grid. This is one of the things
I learned at one of the EMI/EMC classes I took at when I was working at
Rockwell-Collins. I understand that different folks have different
approaches to board design, and these different approaches do work well, my
approach has been ok, with boards I have been designing well up to 5GHz. I
do need to state that I am not the foremost expert in this field; I am just
a simple soul that is scratching the surface of the RF realm!

Given that the highest HF frequency is 30-Mhz, then 1/10 wavelength
would be about 1-meter. This is much larger than the circuit boards in a
radio like the R8, so how important would it be to adhere to the 1/10
wavelength rule for grounding an HF board?

We were discussing what had to be done to prevent board features from
becoming resonant structures on the board and yes at 3 to 30 MHz it's
much less likely due to propagational effects alone but still possible.
If a trace on the board is not closely associated with a ground plane
then its impedance is high and can look more like a lumped inductor than
a transmission line. If the following input to the next device or
circuit has enough capacitance it could resonate anywhere in the HF
spectrum. There are other reasons for via spacing like tying ground
planes together so they look unified electrically. One goal dictating
via density in board design is to make the RF return current path for a
device on the board as small as possible.

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Telamon
Ventura, California