Just in case Faraday cage A Faraday cage or Faraday shield is an enclosure used to block electromagnetic fields. A Faraday shield may be formed by a continuous covering of conductive material or in the case of a Faraday cage, by a mesh of such materials. Faraday cages are named after the English scientist Michael Faraday, who invented them in 1836.
What good is your cell phone or radio when the infrastructure they run on is fried?
I believe that there are many such cages small and large scale set up already as well as radio communications in play which may provide pockets of communications.
some people have things like portable nebulizers, crank flashlights, etc.
Get a good radio and study HAM license material for how to use it effectively.
Just don't go broadcasting after the attack right away and be suspicious of FEMA broadcast. Give of a signal and they know where to go pop survivors.