A dual broadband and multiband antenna system of reduced dimension is preferably an external antenna adapted for vehicles. The antenna system comprises first and second radiating elements and a common ground plane for the first and second radiating elements. The ground plane comprises at least three planes, wherein a first and a second planes are parallel to each other, and wherein a third plane is connected with the first and second planes and it is orthogonally arranged with respect to the first and second planes. The first and second planes extend from the third plane in opposite directions so as to define generally a Z shape in a cross-sectional view. The antenna system is preferably adapted to operate on the LTE communication network.