Design of a Low-profile Chipless RFID tag Using a Grounded Wall

An 8-bit chipless radio-frequency identification (RFID) tag with a compact structure is proposed in this paper. Designing a RFID tag with a compact size is highly demanded in RFID technology. The original RFID tag is composed of 8 octagonal rings. In order to minimize its dimensions, the tag is divided in two equal parts. One part is completely omitted with its substrate. A grounded wall is placed in front of the remaining part to compensate the effects of the removed part and generate an image of it. Comparing a radar cross-section (RCS) of the compact and normal structure implies that by minimizing the tag, the RCS response of the structure is approximately similar with that of the normal tag. An equivalent circuit model for the RFID tag is presented, which shows a reasonable agreement with its full-wave result. The presented tag exhibits an RCS of σ = −26 dBsm from 2 to 7 GHz with an overall size of 15 × 30 mm2. Through using the aforementioned method, a 50% reduction in the overall area of the structure is observed.