What type of horn to use for designing a feed for parabolic reflector antenna?

Probably a low gain horn.

There is a software package, SABOR, that might get you started without too much pain.

To get helpful comments you really need to define your situation more.

What is the frequency range you are looking for?
There are different types of horn feeds for parabolic reflector antennas.
are you designing for any Radio astronomy dish?
Then i may be able to suggest you.
Give some specs.

My frequency range is 10GHz, the parabolic reflector antenna will be used for satellite linking.

So its single frequency right? only 10 GHz.
No broad band horn.
Then Refer what Azulykit has suggested.
It is suitable for your application I suppose.

hi horzcat,
you can use hfss to simulation horn antenna, however you can use feko to simulation this. feko is powerful with antenna placement. it's useful for you when designing satellite
if you use hfss, you can use waveport
if you use feko, you can use wireport like its example or AW card with waveguide port to simulate
good success horzcat

The waveguide port is available in CADFEKO in FEKO 5.4
No EDITFEKO necessary :D

yeah ~.~ mvr