An antenna device designed to be installed on a portion of a vehicle body, comprising: a support base defining a horizontal plane and designed to be arranged resting on said portion of the vehicle body, an inner casing having a three-dimensional shape that is coupled to said support base to delimit an internal housing space, an outer casing structured to cover said inner casing, electronic signal processing means, that are arranged inside said inner casing and are designed to receive/provide an antenna signal, a first antenna element that defines at least one capacitive antenna element and comprises a plate-shaped element arranged on the upper portion of the outer surface of said inner casing, and a second antenna element defining at least one inductive antenna element, that is arranged in said internal housing space of the inner casing and is structured to electrically connect said first antenna element to said electronic signal processing means so as to receive/provide said antenna signal, said second antenna element comprising: a plate-shaped support body made of electrically insulating material, which is arranged on a vertical plane approximately orthogonal to said support base and off-centre with respect to the vertical centre-line plane of said inner casing, and at least one spiral element that is arranged on a vertical surface of said plate-shaped support body and comprises a plurality of turns made of electrically conductive material, which lie concentrically about a first common axis approximately orthogonal to said vertical surface of said plate-shaped support body coplanar with one another on the same surface. a support base defining a horizontal plane and designed to be arranged resting on said portion of the vehicle body, an inner casing having a three-dimensional shape that is coupled to said support base to delimit an internal housing space, an outer casing structured to cover said inner casing, electronic signal processing means, that are arranged inside said inner casing and are designed to receive/provide an antenna signal, a first antenna element that defines at least one capacitive antenna element and comprises a plate-shaped element arranged on the upper portion of the outer surface of said inner casing, and a second antenna element defining at least one inductive antenna element, that is arranged in said internal housing space of the inner casing and is structured to electrically connect said first antenna element to said electronic signal processing means so as to receive/provide said antenna signal, said second antenna element comprising: a plate-shaped support body made of electrically insulating material, which is arranged on a vertical plane approximately orthogonal to said support base and off-centre with respect to the vertical centre-line plane of said inner casing, and at least one spiral element that is arranged on a vertical surface of said plate-shaped support body and comprises a plurality of turns made of electrically conductive material, which lie concentrically about a first common axis approximately orthogonal to said vertical surface of said plate-shaped support body coplanar with one another on the same surface. a plate-shaped support body made of electrically insulating material, which is arranged on a vertical plane approximately orthogonal to said support base and off-centre with respect to the vertical centre-line plane of said inner casing, and at least one spiral element that is arranged on a vertical surface of said plate-shaped support body and comprises a plurality of turns made of electrically conductive material, which lie concentrically about a first common axis approximately orthogonal to said vertical surface of said plate-shaped support body coplanar with one another on the same surface.