Frequency-Coded mm-Wave Tags for Self-Localization System Using Dielectric Resonators

Abstract

The paper describes the development of passive, chipless tags for a novel indoor self-localization system operating at high mm-wave frequencies. One tag concept is based on the low-Q fundamental mode of dielectric resonators (DR) which exhibits peak scattering at its resonance frequency. As the radar cross-section (RCS) of DRs at mm-wave frequencies is far too low for the intended application, arrays of DRs and combinations with dielectric lens and corner reflectors are investigated to boost the RCS while keeping the scattering retro-directive over wide-angle incidence. Satisfactory results are demonstrated experimentally in Wband with metal corner reflectors combined with planar arrays of DRs; the tags produce a high RCS level over a moderately broad angular range and a wide frequency range where they exhibit a notch at the resonance frequency of the dielectric resonators. These designs suffer from low coding range of 3 to 6 bit, degradations of RCS in angular range, and a difficult separation of the tag response from strong clutter. Both the suppression of large clutter interference by using time gating of the tag response and a larger coding range are promised by a chipless tag concept based on multiple high-Q resonators in photonic crystal (PhC) technology. Experimental samples are characterized as transmission resonators and as retro-directive tags at the 230 GHz band. As a concept to boost the retro-directive RCS with a truly wide-angle response, the integration of PhC resonators with a Luneburg lens is discussed.

Wide-Angle Ceramic Retroreflective Luneburg Lens Based on Quasi-Conformal Transformation Optics for Mm-Wave Indoor Localization

“…For example, Van Atta arrays are formed by planar patches [1] or substrate integrated waveguides [2]. Moreover, frequency-coded corner reflectors are achieved by employing frequency selective surfaces [3]-- [4] or dielectric resonator arrays [5]- [7]. A large amount of retroreflective structures are based on lenses by incorporating a reflective layer, such as frequency-coded fused silica spherical lenses [8]- [9], or lenses backed by a photonic crystal (PhC)-based structures [10], such as a polyethylene lens with a Bragg grating [11], and planar [12] or spherical [13] gradient-index Luneburg lens backed by planar PhCs.…”

A Fully Optoelectronic Continuous-Wave 2-Port Vector Network Analyzer Operating From 0.1 THz to 1 THz

“…1 If the VNA is used to measure linear devices or materials with a relatively broad spectral response, the aforementioned disadvantages are no noteworthy limitations. However, if the VNA is used to measure devices or materials with narrow resonances, the resolution may be insufficient [13]. Further, the simultaneous presence of thousand of different frequency components might become problematic when measuring nonlinear terahertz components, like transistors, mixers or simple receiver diodes.…”

Clutter Suppression for Indoor Self-Localization Systems by Iteratively Reweighted Low-Rank Plus Sparse Recovery

“…Although they showcase lower ranges than their active counterparts, owing to the lack of a powered supply, they can be considered as cooperative radar targets that, without actively participating on the communication link, reflect a wave back to a reader. In this direction, several tags have been developed over recent years [ 3 , 6 , 7 , 8 , 9 ]. Assuming that these passive tags are located at fixed positions, and by detecting several of them, a reader can estimate its own position inside a common Cartesian coordinate system by time-of-flight and trilateration techniques [ 10 ].…”