Abstract: An assembly for mounting an antenna on the body of an automotive vehicle comprises a substantially cylindrical mounting sleeve with an outwardly facing circumferential groove for gripping the edge of a preformed hole in the vehicle body upon an insertion of the sleeve through the hole in a mounting operation. The sleeve is formed with a substantially spherical inner surface in the region of the groove for engaging a matching spherical surface at one end of an antenna casing, the matching spherical surfaces providing a water-tight seal while enabling the casing to assume any of a plurality of orientations with respect to the vehicle body. The sleeve has a bellows-like wall formed at an end opposite the groove with a bead for engaging a cylindrical surface of the antenna casing in a water-tight form fit regardless of the orientation of the casing with respect to the body. A mounting bracket provides mechanical support and an electrical ground for the antenna casing.