you dont need a circuit, a diagram or the Ku band ... you're using the parabolic dish to collect and focus em radiation ... the wavelength of the radiation is not so important here (as long as the dish can reflect it, it will work as I understand things)
you need to discard the factory feed and build your own ... either a cantenna or a bi-quad works well, and you'll see fantastic range.
If you're working with a large primestar dish, you'll be better served by taking the mounting apart and inverting the dish, since the feed arm is offset, the focal point of the dish is not 90 deg perpendicular to the feed point ... inverting the dish will let you aim it easier at ground based locations, rather than off into space.
oh I should add ... to save yourself some expense and cable losses, get yourself a cheap-o USB wifi card and hack it open. then you can use a short piece (6") of cheap coax like RG6U (for cable tv with cable modem) to solder from the antenna connection on the wifi card directly to your active element (cut the trace leading to the pcb dipole). this eliminates expensive connectors and microwave cable, now you can use cheap usb cable (up to 6 meters (iirc) without a booster) to run the signal back to your computer.... taking this a step further, with some carefull crafting and trial-and-error, you could place the usb card dipole directly in the focal point of the dish ... problem here is the dipole radiates omnidirectionally, so only a small fraction of its energy gets collected by the dish ... thats why the cantenna or bi-quad make better feeds.