Originally Posted by
AEK42
I understand that the state of Wisconsin was the antenna for the very low frequency transmissions to submarines. My group did mapping for it.
I believe you're referring to the ELF system. And yes, northern Wisconsin contained part of the antenna with Minnesota containing the rest. What they did was to take upwards of 1500 miles of high power electrical transmission lines out of the power grid and that became the long wire antenna. I know they tried different lengths and what they settled at I don't know. It quite literally thumped the ground and took that route to the subs.