@profdc9@mastodon.social in this type of antenna, the mast is insulated from the ground. The feedpoint is at the base of the tower, which is the apex of a conical arrangement of wires tgat go from the base to the circumference of the ring at the top (which is itself supported by wires at the top of the mast.) Think of the small UHf/VHF discone antennas mounted on roofs, but turn them upside down. Here, the “disc” is the ground.