Hi ChuckMcM!

If you are interested , i also developed last year a PLA Luneburg lens for Band X (8Ghz to 12Ghz) using a conventional FDM printer.

We obtained a 6dbm gain @10Ghz

https://github.com/jboirazian/LuneburgLensGenerator

https://polar.sh/jboirazian/posts/why-luneburg-lenses-are-co...

Awesome. That is pretty much exactly what I was thinking of doing. My thought was that you could more easily weatherize something like this rather than a parabolic dish which has a lot of wind loading.

What filament did you use?

Conventional PLA. Since its the cheapest and surprisingly extremley stable for Ghz range RF applications

I recommed you to read the research paper "Measuring the Electrical Properties of 3D Printed Plastics in the W-Band "

(https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=10...)

It was really useful for us when developing our lens with an FDM printer. Be warn that it does require an infill of 100% , so it will be quite heavy.

6 dB gain? 'dBm' is db gain relative to 1 milliwatt of power.

Based on the literature the measure would be 6dBi (relative to isotropic). This is often referred to as 'gain' as it represents sensitivity to the band of interest at a given angle of arrival.

Yes, antennas are normally measured relative to the theoretical 'isotropic' radiation pattern. Sometimes, dBd is used - gain relative to a dipole.

But, even then, you have pattern E and H plane measurements. https://www.data-alliance.net/blog/antenna-radiation-pattern...

We'll discuss this with an eyeball QSO in November...

In the paper they were measuring signal gain between two antennas, and as such the 6dBm gain appears to be the effect of collating more of the beam spread into the receiver (as one would expect of a lens). Given my schedule I don't think I'll have enough time to print one by November but it would make for some excellent discussion! Reading the permittivity paper that was linked here was also quite good and I'm wondering if something could be integrated into openEMS which would tie the two together.

I'm also tickled by the idea of a 'Newtonian' RF telescope using two lenses.