Ultrathin Dual-Band Metasurface for UHF-RFID and WLAN Applications

This paper presents an ultrathin dual-band metasurface which exhibits a linear-to-circular polarization conversion reflection band at the 865MHz UHF-RFID band and a co-polarized transmission band at the 2.45GHz WLAN band. When a linearly polarized UHF-RFID reader antenna is placed in front of the metasurface, the linearly polarized wave of the antenna is converted to a circularly polarized wave after reflection from the metasurface. This reflected circularly polarized wave can be used to detect RFID tags. Once the required information is collected from the tags, the RFID reader can then transmit this information via the 2.45GHz WLAN band through the metasurface. This is possible because of the pass-band of the metasurface at 2.45GHz. The metasurface therefore acts in the reflection mode at 865MHz and in the transmission mode at 2.45GHz. The metasurface has an angular stability of 20° for both TE and TM incidence.