Self-diplexed antenna based on metamaterials for RFID application

In this paper a self-diplexed antenna is proposed for a RFID transponder application. The development cycle is divided into two stages: antenna design and filters design. The antenna is based on a square microstrip patch filled with metamaterial structures. The inclusion of these structures allows simultaneous operation over several frequencies, which can be arbitrarily chosen. The antenna working frequencies are chosen to be 2.45 GHz (receiver) and 1.45 GHz (transmitter). In addition, the antenna is fed through two orthogonal coupled microstrip lines, which provides high isolation between both ports (> 20 dB). Some filters based on left-handed particles are coupled to the antenna feeding microstrip lines have been included to avoid undesired interferences. This approach avoids using of an external filter or diplexer, providing high size reduction and a compact self-diplexed antenna.