In July 1962, a 1.44 megaton United States nuclear test in space, 250 miles above the mid-Pacific Ocean, called the Starfish Prime test, demonstrated to nuclear scientists that the magnitude and effects of a high-altitude nuclear explosion were much larger than had been previously calculated.
Starfish Prime made those effects known to the public by causing electrical damage in Hawaii, about 898 miles away from the detonation point, knocking out about 300 streetlights, setting off numerous burglar alarms and damaging a microwave link.
The electromagnetic pulse (EMP) damage of the Starfish Prime test was quickly repaired because of the ruggedness (compared to today) of Hawaii’s electrical and electronic infrastructure in 1962 and the relatively small magnitude of the Starfish Prime EMP in Hawaii and the relatively small amount of led some scientists to believe, in the early days of EMP research, that the problem might not be significant.
Subsequent calculations showed that if the Starfish Prime warhead had been detonated over the northern continental United States, the magnitude of the EMP would have been much larger because of the greater strength of the Earth’s magnetic field over the United States, as well as its different orientation at high latitudes. These new calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that EMP could be a significant problem.
The military pressed on. And now, in their terminology, a nuclear warhead detonated hundreds of kilometers above the Earth’s surface is known as a high-altitude electromagnetic pulse (HEMP) device. Effects of a HEMP device depend on such factors as the altitude of the detonation, energy yield, gamma ray output, interactions with the Earth’s magnetic field and electromagnetic shielding of targets but the most likely outcome is a massive erosion of communications capabilities for a prolonged period of time.
We know that an EMP, whether military or from a freak sunburst, is very likely to fry all electrics that are exposed to the EMP pulse, or flash. So to be properly prepared, you need to be able to shield your communications devices like your cell phone (for when the towers are back up), your shortwave emergency radio (emergency government communications) your CB radio (to talk to friends) and your Ham radio (for serious long-distance information exchanges.)
Defend Your Communications System
A Faraday cage or Faraday shield is an enclosure formed by conductive material or by a mesh of such material. Such an enclosure blocks external static and non-static electric fields by channeling electricity through the mesh, providing constant voltage on all sides of the enclosure. Since the difference in voltage is the measure of electrical potential, no current flows through the space. Faraday cages are named after the English scientist Michael Faraday, who invented them in 1836
Saving small items
Put your cellphone in a non-conductive paper bag. Seal completely. Wrap in aluminum foil. Place in Ziplock bag. Repeat.
Get an old-fashioned metal trash can with tight metal lid, line completely with Styrofoam or cardboard. Place electrical object inside making sure not to touch anything metal.
Place your phones and radio in to a microwave oven, close door and hope it has a good seal!
Advance planning – Build a Faraday Cage
Find a large metal box of some sort – an old filing cabinet is a good option. Whatever you use has to be metal on every surface or it won’t work. Put insulated packing material inside the metal box. Place the items you want to protect for an emergency inside the box. Make sure they’re protected from the sides of the box by the packing material. Close the box. Cover any gaps in the container’s metal sides with copper mesh. And solder the mesh in place.