This is a customizable horn antenna with the a flange generated from WR112 to WR28. Needs to be metalized to function (or metal casted). Attention: The customizer shows reversed face, the resulting stl works. Openscad does not show this problem.Select the proper WR code, and in addition to this you can define some parameters as length of the wavguide (from the flange border) till the horn starts. The horn has an opening for a optimal horn (based on http://www.ece.mcmaster.ca/faculty/nikolova/antenna_dload/current_lectures/L18_Horns.pdf), Its a work in progress, I didnt test the results yet other than printability. Please feedback also if I did a mistake in the formulars. Before econnecting to a waveguide adapter, metalize the surface and check that the impendance is low for the inner sides and the flange plane.