Usually mast antennas are series-excited (base driven); the feedline is attached to the mast at the base, so the base of the antenna is at high electrical potential and must be supported on a ceramic insulator to insulate it from the ground.
Usually mast antennas are series-excited (base driven). The feedline is attached to the mast at the base. The base of the antenna is at high electrical potential. The base of the antenna must be supported on a ceramic insulator. This was to insulate it from the ground.