Device for transmitting and/or receiving radiofrequency signals

An apparatus for transmitting and/or receiving radiofrequency signals comprising at least a broadband antenna and a substrate;

• the antenna comprising at least a first radiating surface and being superimposed on the ground plane, the ground plane being located on a first face of the substrate, at least a side tongue of a power supply and at least a side wall connected to at least the first radiating surface, wherein:
• the antenna comprises at least a second radiating surface excitable by coupling with the first radiating surface,
• the side wall is connected to a coupling trace located on a second face of the substrate, the second face opposite to the first face of the substrate, and the side wall and the coupling trace being configured to act as a capacitive coupling between at least the first radiating surface, the second radiating surface and the ground plane, and
• wherein the coupling trace is configured to form a coupling capacitor whose value is εS/e where ε is the dielectric constant of the dielectric material constituting the substrate. S is the surface of the coupling trace and e is the thickness between the coupling trace located on the second face of the substrate and the ground plane located on the first face of the substrate, and
• wherein the first face of the substrate is a lower surface of the substrate and the second surface of the substrate is a surface of the substrate above the first face.