question about stub matching

[Manchested]

in stub matching, why is it important to keep the stubs length short?

 

[AmrZohny]

It is important to keep the total stub length as short as possible, if wider bandwidths are required.

Every time you add a half wavelength to the stub length the reactance of the stub comes back to the same value.

It is good design practice to make stubs in the range 0 to 0.5 wavelengths long. However, this may require an impractically short stub, so then one can make the stub just a little over 0.5 wavelengths.

Re-check here...

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[vfone]

It is good design practice to make stubs in the range 0 to 0.5 wavelengths long.

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How looks a 0 wavelength stub?

 

[AmrZohny]

It is a theoretical value for high-frequency applications. ( > 60 GHz applications ).

The same way you mention a pulse (infitinitely small in time) in communications while you always have a certain time for it in real life in pulse generators.

 

[Manchested]

does it somehow affect the resonant frequency if the stub too short?

 

[AmrZohny]

" How Long is Too Long? A Via Stub Electrical Performance Study "

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