Passive UHF RFID tag localization on 2D waveguide sheet using single reader and phased array coupler

In this paper we propose a radio frequency identification (RFID) tag localization scheme on a two-dimensional waveguide sheet. A single RFID reader and the waveguide sheet is connected via a phased array coupler. A radio frequency (RF) signal is transmitted from the reader and its focus is formed in the sheet by the phased array. The focus can be steered by individually controlling the phase delays of transmission lines in the phased array network. By scanning the focus over the sheet sequentially and examining the tag response strength at each focus position, the tag position can be estimated as the focus position where the response is maximized. We demonstrate that the system can distinguish which section the tag is at, where 40 × 30 cm
²
area on the waveguide sheet is divided into 9 sections, by using a 950-MHz ultra high frequency (UHF) RFID system.