I finally tried to make a board with a PCB trace antenna, using the script you provided me ages ago.
In Razen it looks fine. The trace is supposed to be 0.5mm wide. When I try to use width=0, it measures to exactly 0.5mm.
In the gerbers, it's always 0.75mm. I have tried different settings for width, including 0, 0.1 and 0.25mm.