Frequency-Coded Lens by Photonic Crystal Resonator for mm-Wave Chipless RFID Applications

One-dimensional Photonic Crystal (1D PhC) resonator is recently introduced as a good nominee to replace conventional tags at mm-wave and THz bands. For a use of such tags as landmarks in mm-wave indoor self-localization systems, an augmentation of their RCS is required to improve the reading range. As a solution, we propose the integration of a 1D PhC resonator with a dielectric lens (i.e. frequency coded lenses). This concept is demonstrated by locating a 1D PhC resonator in the focal area of a spherical dielectric lens made of PolyPropylene (PP) material with a relative permittivity of 2.0. On the other hand, the PhC resonator is designed by introducing a defect layer between two quarter-wave Bragg mirrors in order to produce a notch signature in the backscattering. Two frequency coded lenses of 24 mm and 40 mm diameter are simulated, fabricated, and experimentally examined. Results show that these coded lenses can achieve 9 dB and 14 dB improvement in RCS, respectively.