I'm working on the operating theory that Santa is not primarily a physical phenomenon, as the energy expenditure from his travel should have significant effects on atmospheric conditions as yet unseen, and so the radar trace monitored by NORAD is a distraction. An adjustment of Santa's EW capabilities evolving in lockstep with the development of sensor technology would, given Claus's clear advantage in technological development, be supportive of such a counter intelligence strategy. If I had to guess, there has been no relative change in sensor signal responses from Santa over the period of this tracking program.