Microstrip Coupled line impedance matching

[khungbopro]

Hello everyone, could you help me this problem :-?

I design a microstrip bandpass filter using coupled line model.
Some parameters of my circuit:

• Zin, Zout = 50 Ω

• f_center = 6.142 GHz

• Order N = 5

• In the input resonator, \[{Z}_{0e }\] = 82.664 Ω, \[{Z}_{0o }\]=37.623 Ω \[\Rightarrow\] \[Z = sqrt{{Z}_{0e }*{Z}_{0o } \] = 55.768 Ω

How to impedance matching Z and Zin?
Thanks alots :-D

This is my design in ADS, (some parameters in schematic was changed after tuning)


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up.........

 

[BigBoss]

Your calculations is not exactly correct.Odd and Even mode impedances are valid only and only if there are 2 coupled lines.But if there are more than 2 coupled lines like in your filter structure , it's hard to say that formulae will still be valid in any case.You forget other interactions between-for instance- first element and kth element.
If you do a EM simulation, you will see that your calculation is not exact but maybe approximate.

 

[RealAEL]

Why are you using MCLINs to construct this filter? The unconnected pins on the 4 pin device mean that these connections are not being calculated correctly, they assume something should be connected there. Using the 2 pin MCFIL element, just above it in the Microstrip palette, would be much better and yield more accurate results for a given topology.

 

[khungbopro]

Your calculations is not exactly correct.Odd and Even mode impedances are valid only and only if there are 2 coupled lines.But if there are more than 2 coupled lines like in your filter structure , it's hard to say that formulae will still be valid in any case.You forget other interactions between-for instance- first element and kth element.
If you do a EM simulation, you will see that your calculation is not exact but maybe approximate.

I have calculated in #1. Could you guide me more!?

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Why are you using MCLINs to construct this filter? The unconnected pins on the 4 pin device mean that these connections are not being calculated correctly, they assume something should be connected there. Using the 2 pin MCFIL element, just above it in the Microstrip palette, would be much better and yield more accurate results for a given topology.

View attachment 100420

I used LineCalc tool and it selected MCLIN automatically

 

[khungbopro]

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