wayfar3r
Newbie level 6
I've designed microstrip and stripline filters at S-Band that have excellent performance. Because the propagation mode is nearly TEM, I expected performance to be even better at UHF. That's not what I'm observing. Both stripline and microstrip are showing extremely high losses compared to the theoretical models. This is true for FR4 and a variety of high and low dielectric Rogers materials I've tried (I'd never use FR4 at S-Band, but I thought it might stand a chance for UHF). These are high order (7 element) filters. I've made similar order filters at S-Band though (at least 5 element). I still see distinct poles in the response, so I don't think its quite as simple as the elements just being de-Qed. The best theory I can come up with is that, because the resonant elements are so much longer at UHF and the 50 ohm lines are wider, my dielectric losses are increasing substantially. Is this the likely cause of my high insertion loss and mediocre response?
I'm using IFilter in AWRDE, then exporting to schematic. I'd move to a 2.5D simulator, but the schematic results don't even meet my design requirements.
I'm using IFilter in AWRDE, then exporting to schematic. I'd move to a 2.5D simulator, but the schematic results don't even meet my design requirements.