Radio transmitting through the ground
OK, I know that radio waves don't really work well in the ground, but it is the best analogy I could think of for this question.
Back in the mid 1960's, I remember reading an article in Popular Electronics, or similar magazine, about building a device that allowed people to communicate through a device that transmitted through the ground. It worked basically like a radio, but used a ground pole instead of an antenna. I remember that the range on it was at least a mile or two and that it worked better when the earth was wet, like a day or two after a good rain. This was a setup that they showed how to build and was simple enough for home construction.
I have never seen nor heard of such a setup since.
Has anyone heard of this, know what it is called and have any information about it?