Gradient-Index-Based Frequency-Coded Retroreflective Lenses for mm-Wave Indoor Localization
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This article introduces retroreflective lenses for millimeter-wave radio-frequency indoor localization. A three-dimensional (3D) gradient-index Luneburg lens is employed to increase radar cross section (RCS) of photonic-crystal high-Q resonators and its performance is compared to conventional radar retroreflectors. A classic Luneburg lens with and without a reflective layer is realized with 25 mm diameter (6.7 lambda(0)), showing a realized gain of 24.6 dBi and a maximum RCS of -9.22 dBm(2) at 80 GHz. The proposed Luneburg lens with embedded high-Q resonators as frequency-coded particles in a photonic crystal structure, operating as a reflective layer, achieved a maximum RCS of -15.84 dBm(2) at the resonant frequency of 76.5 GHz and showed a repeatable response each 18 degrees over +/- 36 degrees in two perpendicular planes. With this high RCS of the Luneburg lens, a maximum readout range of 1.3 m could be achieved compared to 0.15 m without the lens at 76.5 GHz for the same transmit power, receiver sensitivity, and gain of the reader antenna.
KeywordsGradient-index, luneburg lens, retroreflective lens, retroreflector, photonic crystal, chipless RFID, indoor localization, mmWave, RCS enhancement, artificial dielectric
Document typePeer reviewed
Document versionFinal PDF
SourceIEEE Access. 2020, vol. 8, issue 1, p. 212765-212775.
- Ústav radioelektroniky