Hello,
I have come across the exact same problem. This is not an issue just
for high frequency behaviour of the circuit but also with the
etching. This staircase step in direction of the 45 degree bend can
create a bridge and with hobbyist means for etching it certainly will.
I have started looking at the code, it seems everything happens in
zones.cpp in the pcbnew subfolder. I didn't have time to dig into it
but I think the main idea is to fill the area with edge joining
tracks going left to right in one pass and top to bottom in another
pass. The thickness of the track is probably given in the fill
parameters but I think this is not the problem.
The problem is with the internal representation of the tracks I think
that do not seem to take the 45 degree bend into account thus
resulting in a gap on the outer side of the bend that gets filled
since it is thought to be outside the clearance area. The inner side
of the bend gets processed correctly since the clearance area of both
tracks overlap there.
If you try with very thin tracks (say 0.025 mm) and a much larger
clearance (say 0.635 mm) it works nicely which leads me to think this
is how the program works.
I will try to have a closer look when time permits, for now this is
food for thought if anybody wants to also have a look.
I think this problem leads to unrealizable boards when using copper
pouring zones which is a pity for an otherwise very good software.
Cheers, Edouard.
--- In kicad-users@..., Tonamiben <tonamiben@y...> wrote:
Hi,
I tried to create a zone that I filled with copper.
It work good except when there is 45 deg. angles, where the pour
appear
as stair steps.
I was able to modify it in the gerber file by adding a diagonal
line but
for a big pcb it is a big task
to modify a text file and always refere to the coordinate and I did
not
tried the concave curve which I don't know how I can do it in the
file.
Maybe there is an option in Pcbnew to fill the pattern and make
smooth
edge. I ask this
because for high frequency transmission line (PCB coplanar
waveguide)
the calculation of the impedence rely on these gaps between the
signal
trace and the ground plane and I don't know the behaviour of such
stairs
pattern and for the look also.
Is anybody aware about such feature or an easy way to do it?
Thank you