Corner reflector tag with RCS frequency coding by dielectric resonators

For a novel indoor-localization system, chipless tags with high retro-directive radar cross-section (RCS) under wide-angle incidence are required as fixed landmarks. Tags based on dielectric resonators (DRs) were proposed to provide identification by resonance frequency coding. To achieve a satisfactory read range for the localization system, the low RCS levels of these tags require a major boost. A solution was found by adopting the metallic corner reflector which is known for high RCS levels over a wide bandwidth and over a wide angle of incidence. The study presents a novel corner reflector design where notches in the RCS spectral signature are created by the attachment of arrays of dielectric resonators to the metallic surfaces of corner reflectors. It is shown that notches appear due to the increased scattering of the resonators at resonance and by the power loss due to grating lobes formed in addition to the specular reflection from the arrays and from the metallic surfaces. Results from electromagnetic simulations are verified by measurements of an example dihedral corner reflector of 100 × 100 mm² plate size with two arrays of 3 × 3 DRs producing a notch signature at about 7 GHz.