I've had the Pi a bit higher too. Sometimes I could get the repeater to connect the two (the tilt and the pi) but too often, after a couple of days (at most several) they wouldn't stay connected. As I said, I had enough trying to figure it out and went to the pro models. At least those have the signal strength to get through things and connect to the Pi. I did try the repeater in many different locations on the top of the conical. Sometimes it would work for a while, then stopped.
Who knows, maybe I had the 'perfect storm' for getting the standards to NOT work.