faraday cages?

[NorthernSanctuary]

You can't protect a radio in use since the purpose of the antenna is to receive and transmit EM waves. The EMP is an EM wave with a very wide frequency spectrum where the power level is so strong that it overloads and blows the electronics. In fact any unshielded wire (power cord) exposed and connected to your equipment will receive enough power to blow the equipment.