On the Improvement of Baseband Section of Frequency-Domain Vector Chipless RFID Readers

This paper presents the design and fabrication of a high-performance frequency-domain vector reader focused on improving the baseband section of the reader. First, a wideband directive filter for canceling out the strong IF harmonics and local oscillator (LO) leakages is implemented in the baseband of the reader to improve the sensitivity of the reader. Then, a modified gain-phase detector (GPD) module is implemented to find the accurate phase of the tag’s received response, enabling the digital background calibration process in the reader. Later, a high featured and compact control unit is proposed for the digital section of the vector reader. To demonstrate the reading performance of the vector reader, we fabricated a modular single-antenna (SNGA) reader to detect the resonances of frequency-coded-based chipless RFID tags over the C-band (4-8 GHz). The reader uses digital and analogue calibrations to yield a high reading range of up to 60 cm while being compatible with the UWB regulations and at desirably compact geometries.