Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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filter - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: filter Posted: Tue Nov 14, 2006 6:57 am
Joined: Tue Nov 14, 2006 6:50 am
I'm facing a problem in High pass
filter design realised using suspended substrate stripline. the filter
cutoff frequency is 16 GHz. Return loss near cutoff is very poor (-6
dB) and rejection is not monotonically decreasing. it falls down very
sharply upto -40 dB (typically) and then increases by 2 or 3 dB and
remains constant at that level. I have tried various combinations of
substrate parameters, number of elements etc.. Can u please help me
ELECTRONICS RESEARCH LAB
Posted: Tue Nov 14, 2006 7:48 am
Fri Feb 17, 2006 12:07 pm
Location: London UK
would need to know a little more about the filter design type: is it
Butterworth, Chebychev or Elliptic Function? Also how many poles?
The last 2 types have strange behaviour near the -3dB cut off frequency.
If the cutoff roll-off rate in the stop band is very high it suggests
an Elliptic Function or Chebychev filter, and the behaviour may be quite
normal for that type.
They are used when you know the max frequency
can be set somewhat below the max design frequency, but you have several
products or external carriers not far removed from the wanted carrier,
and you need max attenuation of these. The subsequent sidelobes of the
filter then can remain the same level once they have been eliminated.
So, tell us more.