The RFID tag comprises an antenna (11) connected to a wireless communication device (18). The antenna comprises a conductive planar surface and a slot (14) extending at least in a part of said conductive planar surface, the slot (14) forming a non-conductive area of the antenna and defining a first part (12) and a second part (13) of the antenna. The wireless communication device comprises two contact pads (16, 17) being electrically connected respectively each to one of the first and second part of the antenna. The slot comprises a closed end formed by a further conductive part connecting said first and second parts the antenna and further comprises at least one conductive bridge (19-19′″, 20, 21-21″) connecting said first and second parts of the antenna, the conductive bridge allowing to tune the resonance frequency of the tag by varying the length of the electrical path between the pads from the wireless communication device in the antenna.