Improved RCS Chipless RFID Tag Array for Long Reading Range

This paper introduces a chipless RFID array configuration to improve the reading range of the tag by enhancing its Radar Cross Section (RCS). First, a four-bit unit cell tag is designed using multiple concentric Slot Ring Resonators (SRRs) with resonance frequencies at 1.4, 1.8, 2.4 and 5.2 GHz and thus enables binary tag identification coding using On-Off Keying (OOK). Then a 4×4 array tag is designed using sixteen unit cells arranged in four rows and four columns. A bistatic antenna configuration with two horn antennas is used for the measurement, providing a significantly improved RCS value of +20dBsm compared to the unit cell tag. Finally, distance measurements are done in the real environment and exhibit a good reading range with some environmental noise ripples in the RCS spectrum.