I wondered if trace on a single sided PCB could be optimised to resemble a 50 ohm transmission line. It will be enclosed largely between ground areas.
But looking around on the web I have so far only found dual layer calculators for microstrip or striplines with ground planes.
Does anybody know some calculator, reading material or an simply example?
Cheers,
Joop
Hello, What you want is a co-planar waveguide.
Download the milmega RF calculator, it has a line calculator.
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Hello Joop,
The program TXLINE can calculate the impedance for a CPW with or without a ground plane. Google: txline.zip
I just tried the TXLINE-program for CPW with FR4(Er=4.5). Z=50 Ohm, no ground plane W=2mm, gap=0.25mm Z=50 Ohm, no ground plane W=3mm, gap=0.35mm
Best regards, Helmut
CPW=Coplanar Waveguide
Appcad will also do cpw, with and without flip-side ground plane.
Increasing the gap eventually produces the single trace, single-sided board case. In older versions of Appcad, as the gap increased the impedance started going back *down*, but they've fixed that.
Lots of formulas and many programs produce goofy numbers when the situation deviates from their sweet spot. Negative impedances are a dead giveaway that something isn't right.
John
Thanks, at least I know the right terminology now. Always nice to be buzzword compliant ;-)
While trying TXLINE I quickly get an error that the substrate height H should be > 2(w+2g). Your values only can be reached with super thick PCB material (6mm or so). What did you specify to get to these numbers? Perhaps I am not operating the program right.
Joop
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