The SStran at 1680 covers the front 100′ outdoors so that a portable radio gets good signal during frequent yard work. But the back yard’s 100′ is out of range because of being uphill, and a verticle antenna at the ground does not go uphill. Perhaps an angled antenna would work, but for now I’m trying something else.
In the rear I’ll be running a copper wire underground for the full 100′ like a single ground radiator and find out whether that pushes the signal up the hill.
Do you have any predictions?

Just a guess…
Just a guess at what you’re dealing with. Most likely, the ground mounted antenna is not propagating a signal through the structure of the house to the backyard. Elevating the antenna some will help, along with a more complete ground system under the antenna. A buried wire will assist in propagating more signal in its direction due to the wire raising the radiation resistance in that direction. The wire would work better on top of the ground and need not be a bare conductor. Most short radiators produce a signal pattern off the sides of the antenna that look like a squashed ball. So, that means the house is probably your biggest problem. The signal is probably already trying to go up the hill through the house.