Improved Fonts for Chipless Radio-Frequency-Identification Tags Based on Letters

Using embedded microchips on radio-frequency identification (RFID) tags requires difficult mounting processes and increases the tag price. Therefore, chipless RFID tags have been introduced in the literature. In this paper, an improved series of chipless RFID letter-type tags are introduced. Each letter has unique characteristics that can be identified clearly, thanks to the well-designed slits opened to improve its electromagnetic response without sacrificing legibility. Simulations are realized for 150-point Calibri letters, which are also suitable for low-cost inkjet printing, excited with different polarizations. Various types of slits are investigated on the letters to achieve more reliable identification of the corresponding tags. A comparative analysis based on backscattered radar cross section and current distribution results is presented.