Aperture-coupled dual-band circularly polarized antenna for RFID reader applications

This paper presents the design and testing of an aperture-coupled dual-band and circularly-polarized antenna for RFID reader applications. The antenna was designed to cover both UHF (902 MHz ∼ 928 MHz) and microwave (2.4 GHz ∼ 2.5 GHz) bands. The coupling apertures were arranged orthogonally with proper phase offset to achieve circular polarization (CP) at both bands. The fabricated prototype exhibited good impedance bandwidth, an axial ratio of less than 3 dB, and 7dBi peak gain at both bands.