PIFA antenna with tilted circular polarization angle for RFID readers

In this paper, a miniaturized circularly polarized (CP) antenna for RFID readers is presented. This structure, made up of two crossed PIFA has been designed to operate in the European RFID UHF band [0.865-0.868 GHz]. Thanks to two shorts circuits, miniaturization and CP are achieved with only one feed. By optimizing the different parameters of the structure, CP direction can be also tilted in a desired angle. The simulated impedance matching and axial ratio bandwidths are 4% and 16%, respectively. The realized gain is 1.85 dBi at 0.866 GHz. The overall dimensions of the structure are 0.5λ 0 × 0.5λ 0 × 0.06λ 0 .