This is an Amateur Radio Earth-Moon-Earth (EME) 1.296 GHz (23cm band) Septum Feed Antenna Aperture with the attached optional Flare Horn that was designed by OK1DFC (http://www.ok1dfc.com/eme/emeweb.htm#UNITS)
This is only a *part* of a axial or front-feed parabolic dish antenna and was designed to be used in a reflector configuration rather than a Casagrain / Gregorian configuration, but may be used for either as well : https://en.wikipedia.org/wiki/Parabolic_antenna
I have updated the model to include the optional Flare Horn and also added PEM flush nuts for the tuning capacitors.