Microstrip Transmission Line

Hi Everyone and thank you for the answers

I am doing my first design in HFSS and it is about a Microstrip TL. I would like to know what is the procedure, what should I look for. How do I analyze it, when can I say "I am done with it and I am satisfied with the results". How far should the simulation results be from the theory?

I appreciate any comment

Regards
sally

ansoft has an example describing this procedure in detail
i dont have the file but its a pretty straightfoward process
you may be able to dl it from their server or someone maybe able to post it for you

good luck

gb

Here is how to check your work for this example.
Design your microstrip transmission line. Make it longer than 1/4 wavelength. Plot the S11 on a 50 ohm Smith chart starting at zero Hertz and make a note when the spiral 1st crosses the real axis on the Smith chart. Calculate the reflection coefficient at this point. It will be a real number but the sign may be + or - depending on the angle being 0 or 180 degrees. Calculate the actual line impedance using this formula:

Zline = (50 ohms)*square_root[ (1+reflex)/(1-reflex) ]

To check this, I designed a microstrip 100 ohms, 135 degrees long @ 1GHz. It 1st crossed the real axis at 670 MHz, Z=192.3 ohms. Reflection coefficient calculates to 0.5873 @ 0 degrees.

Zline = (50 ohms)*square_root[ (1+0.5873)/(1-0.5873) ]
Zline = 98.06 ohms

This is also the way to check actual transmission lines using a network analyzer.

This is also my question.
I will check tonafishy's method

Zline = (50 ohms)*square_root[ (1+reflex)/(1-reflex) ]
right it is !!

and which port do I use here? a Lumped port or a Wave port?
Can anyone send an example for the micro strip Tx Line design oh HFSS?

Thanks

HFSS is a 3-D EM tool. If you just want to analyze a segment of microstrip line, a 2-D EM tool is much more efficient.
Try Transmatex: SEMSTRA :: Home