For the last couple of years, the meme of an EMP attack against the United States has been an integral part of the thoughtbase of the prepper community.  So the idea goes, the next major attack by a foreign power will involve not the bombing of a major city but bombardment with an electromagnetic pulse (local mirror, snapshot taken 20170310 @ 2030 hours PST8PDT).  Due to the fact that "electromagnetic" is kind of a loose term, sometimes they mean an actual magnetic field, sometimes they speak of a microwave burst (which means that you've got bigger problems than your electronics getting …