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...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Transmission line design - 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: Transmission line design Posted: Sat Jul 22,
2006 3:10 pm
Joined: Tue Feb 21, 2006 5:19 pm
What's the best way of designing transmission
line matching circuits using CAD tools? I am doing a simple single stub
tuned match. I have a series line and a open-circuit shunt stub. I used
the ideal Tline components in ADS to design the match so I have the
value of electrical lengths for both series and the stub. Then, since
I know the frequency and effective permittivity I got the approx. guided
wavelength; then using
physical length (L) = ((guided wavelenth)*(electrical
I got the approx. physical length of the transmission
line. Then, I went in Sonnet and drew up the line and did EM simulation.
But, now I am stuck. For series line, I pretty much was able to match
what ADS had i.e. if the electrical length was 20 deg in ADS for series
line, its S21 mag. and phase was close to the line simulated in Sonnet.
However, I cannot get the Sonnet simulation to match the open-circuit
stub. Its phase way way different and I can't figure it out.
Is the way I am doing sound? Now, I am doubting about using the ideal
Tlines but my thinking was as long as I am able to match s-param, especially
S21, of these ideal Tlines to the simulated lines it should give me
the same match.