Flexible Dual-chip Folded Patch for Polarization-diversity Metal-mountable Tag Design

A novel dual-chip folded patch is proposed for designing a compact radiofrequency identification (RFID) tag that can be mounted on metal surface, operating in the regulated band of (902~928MHz). The proposed tag antenna is fed by two coplanar feedlines, with two microchips bonded, to enhance its radiation performance and achieve polarization diversity in the broadside. The dual-feeding mechanism makes the antenna to have polarization diversity and such feature has been effectively used to improve the read pattern in the broadside, making it readable in a broader angular range horizontally. Two lumped resistors are incorporated into the antenna structure for improving the impedance matching level and bringing the tag resonance down to the ultra-high (UHF) band. The proposed tag antenna has a simple structure and it can be made on the single surface of a flexible PET substrate. It has a compact size of 30 × 30 × 3 mm
³
(0.09l5λ × 0.09l5λ × 0.0092λ). Despite being electrically small, the proposed tag can achieve a maximum read distance of 19.5 m in the broadside. The two-chip tag structure enables polarization diversity and it can be detected in all directions.