Abstract: An adjustable mobile antenna comprising an upper metal mast and a lower metal mast, the upper mast being telescopically received in the lower mast and adjustably movable longitudinally therein to vary the length of the antenna and thereby effect tuning thereof, a clamping member for releasably locking the upper mast in a selected position relative to the lower mast, a dielectric rod extending upwardly from the upper end of the upper metal mast, and a loading coil helically wound on the dielectric rod with a lower end of the coil connected to the upper metal mast adjacent the upper end thereof, and a protective outer jacket covering the loading coil, the antenna being tunable by simply adjusting its length.