A manufacture-friendly multi-layer RFID tag antenna design

A multi-layer tag antenna consists of a feeder and a radiator implemented on different metal layers. It benefits reusing existing tag antenna designs and helps reduce the tag manufacture cost. However, its impedance matching performance is susceptible to the error in the alignment between the feeder and the radiator. A manufacture-friendly antenna, which is insensitive to the alignment error, is highly desired for a successful implementation of the multi-layer configuration. A multi-layer antenna in form of small-loop proximity-fed dipole is proposed in this paper. Its lumped-element model and design procedure are also presented. Parametric study results reveal that, with optimized offset values, the proposed tag antenna is promising to achieve the manufacture-friendly feature. For example, a 0.5-mm alignment error leads to approximately only a 3-MHz shift in the tag resonance frequency. In addition to the manufacture-friendly feature, the read range of the proposed multi-layer tag outperforms the Alien Squiggle tag through the UHF RFID band.