microwaves are a line of sight weppon
ive thought of that, and yes it is true that the weppon is directed by a proton beam, I think the sensor and targeting system is more sophisticated than that
it may be able to detect the ionazation of its suroundings than thus use that to manipulate the beam so that the lighting would hit the target
for example, to fire over a wall into a building, it would know what the ionazation of the building is, and thus it would point the beam over the building, but the lightning would be attracted to the building and thus move in an arc over the wall
thats probly the reasion in the noliva thor had such targeting problems in the beginning, it didnt know how the ionazation would bend the lightning