ANSYS HFSS Physical Optics Solver
As part of the IE solver, HFSS offers a physical optics solver. This is an asymptotic solver that is extremely useful when solving very large electromagnetic problems. As a result it is most useful when solving large reflector antennas or the RCS of large objects such as aircraft and ships. This capability allows you to illuminate any large structure by an incident plane wave excitation or use a "linked" HFSS simulation as a source.
Antenna pattern of an antenna mounted on the International Space Station