hat feed

Hi,
can you tell me, if is it any theory about design hat feed for parabolic antenna ? (picture). Is any theory or is it only "use CST Microwave studio and try it try it and try it"

Thank

try this
pl

Thank,
yes, I know it, because Libor Slama was my colleague and Hazda was my teacher :D. But there is problem, that theory is not the best, it is only "trial-and-error" in CST MWS, I want to use sophisticated method, but fundamental problem of this type hat feed: is very big and expensive.....

In terms of operation concepts :

this looks like a cassegrain reflector to me.

The metal plate is the "shaped sub-reflector" and dielectric is the "region of air" between the subreflector and feed horn.

It may look similar to a Cassegrain but it is not: note that Cassegrain has a primary radiator closer to main dish center; it irradiates the shaped secondary reflector, then the main reflector. This feed only used the reflector to return the field from the circular waveguide backwards. There is no free-space path between waveguide opening and the subreflector.