I saw the other satellite dish and looked at the stl file but didn't like it so I made a new one. my first proper 3d object using tinkercad. 

It uses a 6mm x 3mm magnet to attach to the z axis stepper, print with supports on.

Seti here we come! Enjoy

edit: I have adjusted the reciever arm to be sturdier and added the stl file.

You may want to use the .obj or .stl file to do your own infill and other settings to bring the time down a bit instead of using my unoptimised gcode.

Update: I'm thinking of trying to incorporate ratioed gears to speed up the movement a bit , this obviously relies on getting a design working and Ive never done gear so I need to research a bit to see if I can find something  to use/ modify.