I use a 1,2 or 3 cavity filter which has high Q and the loss is acceptable. A cavity filter in the 28/32 cm band is easy to assemble from a 2lb fruit can and if "tweaked" on a network analyzer can provide >30db rejection with a bandwidth of a couple of Mhz's. There are many texts describing their construction. Contact me off line if you have questions. Procedure I use is, set the filter to the desired center frequency of interest with signal gen, network analyzer, or tracking Gen / analyzer. Determine the insertion loss & record at the center freq. and make the measurement. Then correct for the filter loss. Take this number and factor against the fundamental and your home. I usually re-do at the -3db points of the filter as a sanity check. If the numbers look funny they probably are and you need to check the filter center freq. Repeat for each harmonic of interest. You will probably need to adjust your signal attenuation to keep the measurement in scale. A bit cheesy but worked well for RF guy's the last 60 years. Regards, Michael Taylor Hach Group Colorado
>-----Original Message----- >From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] >Sent: Wednesday, March 20, 2002 11:14 AM >To: emc-p...@majordomo.ieee.org >Subject: Tuned Stub Filter > > > >We are considering using a tuned stub filter to suppress the >carrier so that >we do not overload our spectrum analyzer while measuring >spurious emissions. >One question we have concerns the Q of the filter - i.e., will it >sufficiently suppress the modulation sidebands. So, let me ask >the following >questions. In the frequency ranges of 860-1000 MHz and 2.45 >GHz, how much >suppression should I expect from a stub filter and what design >steps can be >taken to have the necessary bandwidth? Or, am I going down the >wrong path >for a filter? > >Richard Woods >Sensormatic Electronics >Tyco International > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
