Chipless RFID tag with an improved RCS response

This paper introduces a new 20-bit chipless RFID tag with an improved radar cross section (RCS), based on a novel complementary approach with the slot-in-plate array with respect to the array of single resonator-based chipless tags. The backscatter pattern is formed by a rectangular metallic plate 52 × 50 mm² in size etched on a thin dielectric substrate in which an array of 20 shorted coplanar slots is introduced. The originally monotonous RCS frequency response of the rectangular plate exhibits dips corresponding to the presence of individual slots, and thus enables binary coding using amplitude shift keying. The tag has been measured in a bi-static arrangement with two double-ridge horn antennas, and provides a significantly improved overall RCS response compared to an array of resonator-based chipless tags. We also propose two modifications to the inter-arrangement of the slots in order to eliminate the detuning effect of the missing slot representing `0´ bit information on the resonances of neighboring slots representing `1´ bit information.