In a pioneering effort, this research presents a distinctive transformation of the Government College University Faisalabad (GCUF) logo into an RFID tag antenna using characteristic mode analysis (CMA), which resonates at the entire ultra-high frequency (UHF) radio frequency identification (RFID) band for IoT applications. The logo of GCUF is simulated in a computer simulation technology (CST) microwave studio to execute its four characteristic modes at 900 MHz. With the implementation of minor changes in the GCUF logo, optimal conjugate impedance matching with the RFID chip has been achieved. The impedance, reflection coefficient, and far-field pattern are examined through CST. The logo tag antenna is fabricated using a Rexin substrate (artificial leather) coated with conductive paint and a passive UHF RFID Alien Higgs H3 chip attached to the logo for impedance matching. The proposed design has been simulated with a human body model. The read range of the fabricated prototype is tested on different objects, like a notebook, T-shirt, and bag. The measured read range demonstrates the robustness of the proposed logo design across various distances: 3 m for a notebook and bag, and 2 m for a T-shirt, with RSSI values of −61 dB, −59 dB, and −62 dB, respectively.

A meandered-dual-antenna structure is proposed for UHF radiofrequency identification (RFID) tag. It is composed of two independent antennas printed on the one side of the substrate board. One of the antennas is exclusively used for receiving and harvesting sufficient energy to the tag chip having the complex conjugate impedance of the receiving antenna. The other is for backscatter to enhance maximum differential radar cross-section with purely real input impedance, to enhancement the read range. The receiving antenna is formed by a rectangular loop and a parasitic meandered line. The rectangular loop is used as a feeding element for the meandered line. The backscattering antenna is made using a meandered dipole along with a thin rectangular strip. The input impedance of the receiving antenna is designed to be conjugate matched to the chip impedance (13.5-j110 Ω), whereas the input impedance of backscattering antenna alternatively switched to open and short circuit for modulating the backscattered field. The input impedance of receiving and backscattering antennas is measured using differential probe technique. The simulated and measured results are found in good agreement. It is also demonstrated that the read range of UHF RFID system increased considerably by using the dual-antenna structure.

Radio-frequency identification (RFID) technology is a consolidated example of wireless power transfer system in which passive electromagnetic labels called tags are able to harvest electromagnetic energy from the reader antennas, power-up their internal circuitry and provide the automatic identification of objects. Being fully passive, the performance of RFID tags is strongly dependent on the context, so that the selection of the most suitable tag for the specific application becomes a key point. In this work, a cost-effective but accurate system for the over-the-air electromagnetic characterization of assembled UHF RFID tags is firstly presented and then validated through comparison with a consolidated and diffused measurement systems. Moreover, challenging use-cases demonstrating the usefulness of the proposed systems in analyzing the electromagnetic performance of label-type tags also when applied on different material or embedded into concrete structures have been carried out.