do you mean 2:1 like vswr 2x1 would not really be an array I guess you could have a two element array but that is very simple create two dipoles at 3GHz:
Dipole length: 48mm (a little shorter than 1/2 wave for better matching)
Dipole diameter: I would say 200um would be good but don't go much thicker than 2mm or it'll give you funky matching results
Feed in the center of it.
Now place these two elements 180° spacing (50mm) and now you have a side fire 2 element array working at 3GHz. You should get about 5dBi out of this structure.
Hope this helps