RFID tag antennas with stable impedance to mounted material

The following study presents two UHF RFID tag antennas for the identification of mass retailing produces. The antenna is composed of two elements, a planar dipole based antenna matched with a small inductive coil. These tags have the particularity to have stable performances to mounted material. Simulations studied the performance of tag antennas depending on the permittivity and thickness of the mounted material. Tags prototypes ranges are measured on different mounted materials: cardboard, paper block, plastic, wood, bottle of tap water and glass bottle. Measurement results indicated a maximum range of 8 meters for material with a low permittivity and a maximum range close to 2 meters for thicker material or with a higher permittivity.