In this paper, a 3 dimensions (3D) fully metallic antenna for an RFID tag is presented. It is a crooked wire monopole antenna. Close to the frequencies of the European UHF RFID band, it exhibits an input impedance that is the conjugate of the one of the Monza R6 chip. The latter with the proposed antenna presents a reading range of 11.87 meters and occupies a volume of 23 mm x 23.4 mm x 23.8 mm. This 3D tag structure could be useful for applications in metallic environments or applications in very severe environments where nonmetallic materials are useless such as in some aerospatiale applications. With a simple meander antenna, the proposed antenna, the reading range is approximately 6m.