RF filter question
This is a common problem (about symmetry), and some tricks are used to correct this.
Look at this discussion on the old Eagleware forum by Randy Rhea. You may need to do a simple registration to view this, but it is worth the trouble
http://forum.eagleware.com/viewtopic...dpass+symmetry
This is correct, this is a typical preoblem with resonator rods, I know that coupling will place a transmission zero on the high side, but i am sorry i only know about some trial and error aproach.
you can tie with a wire or add caps then connect with a wire, this will couple the resonators, you will have to determine which resonars though, i have seen different ones.
if anyone knows some detailed equations that explin this that wouldf be great
This same problem occurs in LC resonator top coupled filters. One way to look at it is that the coupling capacitors block lower frequencies better than higher frequencies.
In the LC world there is a dual of this filter with series LC sections in a row with a shunt capacitor to ground between each of them. This has better high frequency rejection.
To get symmetrical attenuation, put a little of each type in your signal path.
low Q,and this mean the die loss and conductor loss.
and sometime the radiation loss.
I am sorry what kind of filter are you working with?
I saw this link but just want to let you know that it points to a 404 Not Found fyi
No wonder, it was posted in 2006. A lot happened since then. Randy sold Eagleware out to Agilent.
This is a link to the article on the Agilent site
http://www.home.agilent.com/agilent/...fr=-34360.0.00
Most likely bad grounding!
Thanks for the updated link I didn't know that Eagle ware had been sold... That link was pretty useful so thanks i appreciate it. Also I 'm going to post a link to our RF spec sheets that I hope might help people who are trying to see the type of options that can be used in RF Filters RF Filter Reference sheet