Letter Re: EMP

I currently keep my backup mini-iPad in an EMP bag. Do I also need to keep my power supply for it there, too? Thanks – A.B.

HJL replies: Yes. In fact, it is probably more important that the charger is in the bag than the ipad. Being an electrical engineer with considerable radio technology experience, I have a perspective that is a bit different than most on the subject. The true danger of EMP is in having antennas or things that act like antennas pick up the electrical energy. If the object in question either has wires or parts that could be considered long antennas or is connected to parts that could suffice as such, then the object is in danger of being susceptible to EMP. Many modern cars fall under this category because they are basically networked mini-computers with considerable wire interconnecting the various parts. Your iPad alone does not, unless you have it connected to the charger when the EMP hits. The charger (with cable) and house wiring that the charger is connected to becomes that antenna that makes it hazardous to your iPad. Unless you are at ground zero, or very close to it, your normal electronics won’t have any problems surviving. The advantage to the EMP bag is that it will block any wifi or cellular signal and keep Alphabet agencies from activating the camera or microphone to spy on you. As for protection, the charger is probably more susceptible to EMP than the iPad, just because of the length of the cord attached to it. Most modern electronics are made from such sensitive electronics that they are designed with ESD/EMP protection from the start. The integrated circuit has built-in shorting diodes, and the circuit boards will often have additional protective circuitry. The manufacturers do not know where you will be taking your electronics, and the protection is cheap insurance for them. It is easy to protect objects that are not connected to anything from EMP, because the induced voltages will be so small. It is much harder to protect anything connected to the power lines, phones lines, or even many local computer LANs that have miles of unprotected cable.

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Letter Re: EMP

Hi Jim,

Do you know if we have a EMP attack or if the grid goes down weather we will still have internet service? – GLB

HJL Replies: Since the vast majority of the Internet depends upon the power grid, it really depends on how much of the power grid survives an EMP event. The long hauls of the infrastructure would probably survive due to the fact that most are based on fiber optics, which are not affected by EMP. The hubs, connection points and routers all have to have power though, which is affected by EMP events. If the locations are sufficiently hardened, they may survive. If they are not EMP hardened, they most likely will not survive. I suspect that we would have isolated pockets that would be just fine and most long hauls would be fine as well. The connectivity of the Internet would greatly depend on those areas that are powered by commercial electric power or have sufficient metal wiring to be able to induce EMP spikes large enough to kill electronic equipment with minimal protection. The Internet was designed to be a self healing network (or at least able to route around isolated problems) so if enough infrastructure survives, it may indeed be useful. However, I suspect that it will not be very usable though since the usability is directly related to connectivity.

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