The bottom of the ring is 13 inches off the ground and there are no RF absorbing materials close by. It dips fine and makes contacts but just doesn't seem to be as strong as other antennas. I have a ground screen on the ground under the antenna which consists of welded wire fencing (hog wire).
2011 Update: I gave this antenna away before I had a chance to do much more with it. I don't know if I could have ever gotten it to work better.