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Wideband Filter - RF Cafe Forums
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Antonio
Post subject: Wideband Filter Posted: Tue Nov 27, 2007 6:42
am
Captain
Joined: Sat Jun 16, 2007 12:26 am
Posts:
12
Can anyone tell me:
Why the Return Loss performance is
poor in Wideband Filters?
Or
Why is it difficult to
get good Return Loss performance in Wideband Filters?
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IR
Post subject: Posted: Tue Nov 27, 2007 4:01 pm
Site Admin
Joined: Mon Jun 27, 2005 2:02 pm
Posts:
373
Location: Germany
Hi Antonio,
Wideband filters are
those with a BW>10% of the center frequency
The reason for
that is the same as why it is hard to design a wideband filter with
low insertion loss. When you design a wideband filter, more resonators
are required which increase the insertion loss and thus the return loss.
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Antonio
Post subject: Posted: Thu Nov 29, 2007
6:49 am
Captain
Joined: Sat Jun 16, 2007 12:26 am
Posts: 12
Hi IR,
Thanks for your reply..
Can you
please explain it with the help of circuits? A circuit containing combination
of L and C and some tank circuits.
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IR
Post
subject: Posted: Sat Dec 01, 2007 12:16 pm
Site Admin
Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location:
Germany
Hi Antonio,
The following article mentions this
issue. It describes distributed (printed) filters. The principle is
the same for both distributed and lumped filters.
http://www.eng.jcu.edu.au/Staff/Profile
... 81-Fil.pdf
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Jeanalmira
Post subject: Posted:
Mon Dec 24, 2007 9:25 pm
General
Joined: Tue Mar
15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi Antonio,
I agree with the above posts.
But keep in mind that by adding
more resonators, there will be more insertion loss resulted.
The
difficulty in getting good Return Loss performance in Wideband Filters
is somehow related to the Q concept.
It depends how good you want
the performance is. The smaller insertion loss and the higher return
loss require higher Q, which means it will give sharper response.
I hope it helps.
Regards,
Jean
Posted 11/12/2012
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