I apologize for the late response as I'm just seeing this several months later.
I understand the issue of weight pulling down on it and causing it to separate. To relieve the strain on that joint, tie the knot below it, at the base, below the radials. To keep the antenna vertical tie a loop in the rope near the top. This loop won't hold the weight of the antenna and cable, but it will keep the antenna upright. Diagram attached.