Microwave transparent material for ESR/EPR spectrometer

Hi! Completely forgot about this great forum!

I'm designing an electron spin resonance /electron paramagnetic resonance spectrometer, as an easier vacation from my diy NMR - while still utilizing much of the same setup.

Issue is; I have an X-band (~12GHz) waveguide cavity in a magnet, and I need to be able to adjust the position of a sample in that waveguide without ruining or detuning my cavity. There'll be a bushing in one of the WG shorts with wich to rotate the sample eccentrically, but what material should the sample holding rod be?

I'm not really keen on making it from beryllia... The article I'm kinda following is putting the sample ions in a MgO matrix, would a little sintered MgO rod be the answer?

Thanks in advance!


Science Advisor
Gold Member
These are impressive DIY projects! I would think a low dielectric constant is desirable to minimize detuning, and a low loss tangent is necessary to keep the cavity Q high. I suggest starting with teflon, which has that combination, or looking at styrene or fused quartz if you need a more rigid material. Your cavity will probably need to be retuned if you move anything inside, no matter what.

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