EEVblog Electronics Community Forum
Electronics => RF, Microwave, Ham Radio => Topic started by: jujun on June 20, 2018, 11:11:07 pm
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Hello,
When adding notch/reject filter by putting them in series, will it work?
Is it as easy as the losses are added and nothing more complicated? It sound a little too easy...
And what about the length of cable between the filters ?
Basicaly, I want to block two annoying signals, that are one each side of my band of interest. Is it good to make a notch/reject filter for each ?
Because if I make a band pass, on UHF, the loss are too big. But the added losses of two reject filters are not a very big. 0.5db + 0.5db it's quite good :)
By the way, why it's so different ?
Thank you for any advices :)
Julien
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As long as the notches don't overlap it should work fine. If they overlap there will be a standing wave between the filters and rejection may decrease at some frequencies relative to a single filter.
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As long as the notches don't overlap it should work fine. If they overlap there will be a standing wave between the filters and rejection may decrease at some frequencies relative to a single filter.
Thank you!
So it's wonderful, and it's a lot better than making a band pass!
I will try to make very broad band block filter to see if it's possible to have low losses.
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You can put an isolator between reject filters of the same notch i think
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You can put an isolator between reject filters of the same notch i think
What is it ?
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Tip: You could simulate the circuityou have in mind using SPICE you have in mind so you can predict the effects.
I notoriously do this, results are OK:
https://electronicprojectsforfun.wordpress.com/rf-module-gallery/the-rf-filter-gallery/