and what i mean by that, is we are talking about a pulse of high voltage and very very high frequency (maybe even gamma radiation) and its effect on electronics.

thats not a case of power falloff. Because interaction with the environment and target is non linear.

for example if it blasts a phone to reset from a few centimeters it could easily drop all calls in a 20 meter radius. but upping the power/voltage 4 times may only add milimeters to the range of blasting the phone to reset because so much is absorbed by the case. but upping the power/voltage 5 times could add a meter to blasting the phone to reset because the case now no longer absorbs enough energy to prevent the interference. Also resonance and harmonics play a huge role in the effect.

All conjecture. but my point is you cant apply school boy physics to the problem because its not a problem they teach in school.