so the closer you get to the ILS beacon - the smaller the scale (hence the smaller the movement required to regain / lose track
A small 'amplification' to Alex90's post. An ILS installation is not a 'beacon' in the same sense as VOR or NDB. There are two antennae - a glide slope antenna on the side of the runway, adjacent to the touchdown zone and the localizer antenna which is at the far end of the runway.
By the time you are crossing the threshold, the glide slope is much more sensitive to deviations than the localizer, because the glide slope antenna is only about 1000' away, whereas the localizer antenna is still a mile or more away.