Rotman Lens-Based Wide Angular Coverage and High-Gain Semipassive Architecture for Ultralong Range mm-Wave RFIDs

• Published in: IEEE antennas and wireless propagation letters Vol. 19; no. 11; pp. 1943 - 1947
• Main Authors: Eid, Aline, Hester, Jimmy G. D., Tentzeris, Manos M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Antenna measurements; Backscattering; flexible electronics; Gain; Gain measurement; High gain; Internet of Things (IoT); Lenses; Millimeter waves; millimeter-wave (mm-wave); Modulation; Photovoltaic cells; Power consumption; Power management; Radar cross sections; RFID; smart skin; Solar cells; Substrates
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2020.3002924

In this letter, the authors demonstrate, for the first time, the implementation of a fully-flexible, energy autonomous Rotman lens-based backscattering RFID tag operating in the 28 GHz 5G band. The Rotman lens front end was designed, simulated, fabricated on a thin flexible substrate and its gain and differential radar cross section (RCS) tested. The structure displays a simultaneous high gain and wide angular coverage, resulting in a remarkable RCS, measured in both planar and severe bending conditions. A low power oscillator was then added to the retrodirective array to test its detectability as a backscatterer at an unprecedented range of up to 64 m while displaying a power consumption as low as 2.64 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>W, effortlessly supplied by its flexible solar cell in normal office indoor conditions. Enabled by the implementation of a high degree of focalizing retrodirectivity, this unique Rotman lens-based system could enable the birth of RFIDs with practical reading ranges exceeding 1.8 km.