You can't really shrink a phased array. If you use smaller antenna elements you must use a higher frequency, and higher frequencies are more attenuated by the

You can't really shrink a phased array. If you use smaller antenna elements you must use a higher frequency, and higher frequencies are more attenuated by the earth's atmosphere (generally, when you get to THz there is a window or else visible light wouldn't be able to penetrate) so they have no chance of making it to a satellite. If you use less elements you lose all your gain in the side lobes, as the other commenter mentioned