Guest Editorial on Advanced Antennas for Radio Frequency Identification (RFID) Systems

The RFID community is enjoying new impetus coming from the revolutionary Internet-of-Things (IoT) paradigm and its integration with new application scenarios like Industry 4.0. RFID technology, in fact, enables reliable communication at low cost and with lightweight apparatus, desirable features for pervasive devices employment as desired by the IoT. Nonetheless, commercial-off-the-shelf (COTS) solutions cannot be always employed in some of emerging application scenarios, requiring customized reader and/or tag antenna design. In order to collect the most recent developments in the antenna design research for both legacy and novel RFID application contexts, the IEEE Journal of Radio Frequency Identification proposed the special issue 'Advanced Antennas for Radio Frequency Identification (RFID) Systems'. A RFID system and its performance clearly depend on the antenna ability, both on reader and tag sides, to make the system accessible from short or long distances, and on different environments. The latter is particularly important in the new RFID tag application contexts, e.g., industrial manufacturing processes, vehicular environments, etc., where tags are indifferently applied on heterogeneous materials, many times on metal surfaces, and for this reason the antenna design requires particular care. Moreover, the pervasive diffusion of RFID-IoT devices poses new challenges in inventory assessment, requiring even longer read ranges and wide coverage ability, which clearly translates in new reader/tag antenna requirements. The purpose of this special issue was therefore to encourage the research on novel RFID antenna design solutions for both reader and tag devices to face these new application scenarios and cope with the new challenging requirements. Starting from magnetic coupling resonant high-frequency (HF) RFID systems, Mukherjee et al. consider the annoying problem of HF RFID reading performance deterioration in the presence of metallic conductors in the close vicinity [A1]. This problem arises because of the eddy currents induced on the metal surface by a varying magnetic field generated by the reader coil, which in turn generate an opposite magnetic field that reduces the intensity of the original field, deteriorating the reader-tag communication performance. Authors study the possibility to employ an auxiliary coil in the proximity of the metal surface, and how this mitigates the deleterious surface current effect. Tag coils co-located with the auxiliary coil are fabricated and placed on the cap of a plastic container (where the cap contains an aluminum foil) and on a credit card size metal sheet to benchmark the read range capabilities, showing an almost doubled read range and an improvement of more than 44% if compared with the case no auxiliary coil, respectively.