I'm using Fusion 360 to generate a model and paper drawings so I can machine an intricate and tiny antenna component for the 122 GHz mmwave band from Tellurium Copper using my 1982 Colchester 1800 manual lathe.
A key element of antennas using the Cassegrain topology with a deep parabolic dish and a hyperbolic subreflectoe is the design of a compatible feedhorn. It needs to illuminate the subreflector without too much overspill or under-illumination.
I used OpenEMS to optimise the gain of a simple conical flared horn so that the illumination of the edges of a 48 mm diameter subreflector would be down about 6dB from the central level. I'll probably do a video about the modelling, design and optimisation processes as they are interesting in their own right
In a very deep dish with f/d 0.25, there is an inherent spatial attenuation because the focus is twice as far from the rim as from the centre of the parabolic surface.
