How does a single loop bandpass/notch cavity work?

[archjeb]

Over the past few months I've been reading various duplexer designs and one that I can't wrap my head around is the single loop bandpass/reject cavity. I get the dual loop where the cavity is tuned to be resonant at the bandpass and the Capacitor is tuned to the reject.

But the single loop I just don't get. How by using a tee connector do you get the signal to pass when the cavity is tuned at the resonant frequency?

If anyone has a good reference and deep dive, I'd deeply appreciate it.

Thanks,

J

 

[Moleculo]

do you have a sample schematic to post? That might help add some clarity to the design you're asking about?

 

[archjeb]

do you have a sample schematic to post? That might help add some clarity to the design you're asking about?

Probably the best reference is this presentation:
http://www.repeater-builder.com/antenna/pdf/ve2azx-duplexerinfo.pdf

slide 4 covers 2 loop design. Easy to understand as the loops are magnetically coupled with the resonantor. I can wrap my head around this.

Slide 26, single loop. I can't wrap my head around how this works, especially with a t-connector. The notch I understand with the capacitor, makes peffect sense. But the bandpass part with a single loop is what I don't understand....