A novel, frequency selective surface (FSS) based, data encoding
structure amenable to be used as a chipless RFID tag is proposed. The
data encoding structure is made up of finite repetitions of a unit cell
fabricated on commercially available grounded FR4 substrate having
physical dimensions of 15 × 15 mm². The unit cell is composed
of numerous T-shaped resonant elements arranged as two atypical sets of
concentric nested loops. Alteration in geometry of the encoding
circuit, attained by inclusion or omission of nested resonators,
corresponds to a particular data sequence. Each encoded data sequence is
manifested in the frequency domain as a distinct spectral signature.
The proposed 10-bit tag is both compact and robust, and remains
interrogable in response to illuminating electromagnetic waves at
various angles of incidence.