TEM mode coaxial ceramic resonators, how to use them ?

[jujun]

Hello,

I juste discovered that TEM mode coaxial ceramic resonators exists, and I didnt find a lot of information on them.

Where can I find information on them ?
Did you already used them in a design ?

Thank your for your help

J

[TheUnnamedNewbie]

Arent these just bits of coax cut to size (to be crude, ofcourse they will be optimized to give reliable frequency behavior etc), which you can then use as a classic transmission-line stub/short/etc?

Pretty much the same as your classic "Voodoo RF black magic" microstrip filters, just with better shielding.

[PA0PBZ]

I think I've seen these in (older?) mobile phones as duplex filters. Here's a bit information: http://www.exxelia.com/uploads/PDF/epsilon-90-1-4-v1.pdf

[jujun]

Thank you

So I can see it like an industrial version of a coax stub.

A kind of SMD coax stub

[JohnG]

The advantage over a typical microstrip or coax cable stub is that the ceramic has a much higher dielectric constant for the insulation between conductors. This lets one make it much physically smaller for a given resonant frequency.

John

[phenol]

https://www.minicircuits.com/WebStore/dashboard.html?model=CBP-1034C%2B

i used that one in the past. Really low insertion loss in the pass band, but what the datasheet doesn't show are the higher harmonic modes that start to appear above 2 or so GHz.

I've seen such resonators with loosely coupled varactors in VCOs of old Nokia mobile phones in the 70cm band. I guess they were trying to achieve superb phase noise far out from the carrier.