Assuming your fundamental element is in an array in a particular plane, you can only scan in that plane. Scanning occurs when you add antennas' responses whose delay in receiving or transmitting is controlled. That is, beam forming happens when you achieve constructive interference (add) and destructive interference (subtract) from multiple antennas (elements). The locations where the beams add and subtract are controlled by changing the phase (delay) of each element signal (either by location as in an array, or by electronic signal control)