Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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My Hobby Website:
CPW Calculation - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: CPW Calculation Posted: Wed Sep 19, 2007 9:16
Joined: Tue Sep 04, 2007 7:54 am
With the following parameters,
I am getting different answers with different tools.
H = 0.3mm
Er = 4.25
W = 0.56mm
gap = 0.35mm
With this Agilent Appcad gives 50.2 ohms. AWR Tx line
gives 47 ohms.
Following online calculator gives 78 ohms.
Don't understand the reason for this difference.
Post subject: Posted: Tue Sep 25, 2007 3:01
Joined: Tue Mar 15, 2005 11:43 pm
the difference is
the ground plane.
I believe that for your first calculation (AppCad
and AWR) you included the groundplane (CPW ground)
While the online
calculator is without ground plane.
you can double check the
setting thru AppCad and also AWR (CPW and CPW ground).
Post subject: Posted: Tue Oct 16, 2007 5:40 am
Joined: Wed Jun 20, 2007 3:01 am
I'm with Jeanalmira in his opinion. As for the lower impedance
values you used -most probably- Grounded-Coplanar. While the larger
values is for the conventional coplanar waveguide -without lower ground
Kindly check this online applet, it is for conventional