A shelf antenna using near-field without dead zones in UHF RFID

This paper presents a shelf antenna for near-field RFID systems which has an electromagnetic field distribution characteristic without any dead zones presented widely in the vicinity of reader antennas. These dead zones are caused by the electric-magnetic field cancelation since an incident wave is summed with the reflected wave caused by the terminals on the feed line of an antenna. The proposed antenna is made up of a feed line on the bottom layer and a meander line on the top layer in a rectangular waveguide. The feed line acts as a principle of standing wave having periodical dead zones and the meander line acts as a radiator coupled with the feed line of bottom layer. Therefore, these reactions between the feed line and the meander line make the proposed shelf antenna eliminate the effect of dead zones on the surface of the antenna properly.