Looking for a book that I read years ago, about mysterious radio signals, and a guy who went into a wilderness area to transmit test radio signals, trying to find source of the mysterious signals.
He set up the antenna across a river that that ended on the side of a cliff.
When he hits the transmit button, he is transferred somewhere else, to a facility run by a computer that represented a galactic civilization, and the computer will only give him advanced information and citizenship after he demonstrates that he is ready for it, and recognizes and asks for additional training. He comes across (I think) a woman that says she has been in a time stasis for a long time (stasis looks like a frozen atomic explosion), that later proves to be too long.
The galactic civilization had teleportation, but the equipment was huge. Our hero miniaturized it and had the computer insert it into his brain via microcircuits. They also had a view point/portal that looked like a UFO and they had a stasis field that looked like a frozen atomic explosion.