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.