Is there any PCB tool for 50 ohm transmission lines?

Layout
1

I was amazed by the new push router, and the tool for equalizing lengths, but is there any tool to help with 50 ohm transmission lines? This is such a common problem in RF designs, I know it would be useful to those doing anything where controlled impedance is important. Feeds to RF connectors, attachments to any controlled impedance object and transmission lines between items all could benefit.

Also, is there any way to draw a spiral track in the pcb artwork?
many thanks,
walter

2

The trace width, separation and distance to a ground plane all determine the impedance. I recommend using the free Saturn PCB Toolkit for calculating those parameters. Then setup the transmission-line router in KiCad and draw them.

4

Thank you, I am still learning all the new features, that is very helpful!
I have seen other RF-specific EDA tools that do this automatically, I was just wondering if there was anything similar with KiCAD.

I did see the info on importing an external image for a spiral, but of course that merely kicks the can down the road, and he then had trouble connecting to it, so maybe not the perfect answer. track spirals for antennas and inductors are very handy, but not so simple to achieve within most PC tools, it’s actually easier with tape and film.

all the best,
walter

5

I have used the Saturn toolkit before (under windows), but it doesn’t run on my new linux workstation (might try it with WINE or in a VM), I was hoping for something within KiCAD. I did not see something called “transmission line router”, where is that located?
many thanks,
walter

6

The PCB Calculator module, at the top level of the KiCad controls, next to PcbNew etc, can calculate various type of transmission line impedances.
The spiral track, designed by script in the other thread, will be hard to calculate as the neighbouring loops affect the impedance.

7

Search again…

That procedure will give you real tracks (in segments, not arcs) that you can connect to.
There is no need to further advance it though as KiCAD will have arcs in a not too distant future.
But if you need them now, you can make them.