The requirements of wearable antennas are small dimensions and lightweight as well as high immunity to the human body interaction which may otherwise sensibly change the radiation diagram and degrade the antenna efficiency. Some of these issues are also common to the design of tags for metal objects whose presence strongly affects the radiation diagrams of the attached antenna and prevents the use of dipole like layouts. In active and semi-active architectures, as in the case of body centric communication systems [6], the overall radiation performance is enhanced by additional battery-assisted electronics. In case of passive tags instead, where the energy to produce the response comes from a remote query unit, the antenna design is much more challenging.