This work presents a novel technique for designing chipless radio frequency identification (RFID) tags which, unlike the traditional tags with complex geometries, are both compact and printable. The ...tags themselves are alphabets, which offers the advantage of efficient visual recognition of the transmitted data in real-time via radio frequency (RF) waves. In this study, the alphabets (e.g., a, b and c) are realized by using copper etching on a thin dielectric substrate (TLX-8) backed by a ground plane. It is shown that the original signature of the frequency response of the backscattered radar cross-section (RCS) of the letter, displays dips that are unique to the individual letters. The tags have been simulated, fabricated and their monostatic cross-sections have been measured by using a dual-polarized Vivaldi antenna in the frequency band ranging from 6 to 13 GHz. The study also includes, for the first time, a detailed analysis of the impact of changing the shape of the tag owing to variation in the font type, size, spacing, and orientation. The proposed letters of the alphabet are easily printable on the tag and provide an efficient way to visually recognized them and, hence, to detect them in a robust way, even with a low coding density of 2.63 bit/cm2. The advantages of the proposed novel identification method, i.e., utilization of the both co- and cross-polar RCS characteristics for the printable clipless RFID tags are the enhancement of the coding density, security and better detection of the alphabet tags with different fonts by capturing the tag characteristics with better signal to noise ratio (SNR). Good agreement has been achieved between the measured and simulated results for both co- and cross-polarized cases.
In this paper, we investigate chipless RFID (Radio Frequency Identification) tags based on Arabic Alphabets with points, to be used as RF coding particles. First, the tags were designed by ...considering an Arial font to generate the metallic letters printed on flexible Kapton substrates. Next, the points were connected to form the main bodies of the letters to improve their Radar Cross Section (RCS) signatures when illuminated with incident electromagnetic waves within the frequency band of 2-8 GHz, for both horizontal and vertical polarizations. Good agreement between simulated and measured results has been obtained. We have found that among all of the similar letters studied, those stripline connections provided us the best way to take into account of the presence of the points and then conveniently distinguish the RCS signals characterizing each letter with a unique RF response. Finally, a lookup table for the identification of the 18 letters with punctuation that have been studied has been carried out.
This paper presents an approach for the design of chipless RFID tags by using standard alphabets. To illustrate this approach, the paper considers the alphabet letters (a, b and c) that are realized ...using copper etching on 0.5mm thick Taconic TLX-8, with a relative permittivity of 2.55 and loss tangent of 0.0019. As expected, simulation results demonstrate that the exploitation of resonant frequencies visible in the backscatter signal can be used for purpose of identification. These simulation results are validated by the experimental measurement.
This paper discusses the electromagnetic (EM) signature of Arabic alphabets that can be considered as standards particles to form chipless tags. Normalized Arial font is suited as example but the ...method can be applied for any other font. The letters are realized by metallic strips or better, by conductive ink. All the 28 letters have been simulated and their EM signatures for both field polarizations are extracted. It is demonstrated that combining vertical and horizontal responses allow the identification of letters without ambiguity. Moreover, the case of letter with punctuation (one to three points) is considered in more details. Indeed, we propose to modify very slightly these letters by connecting the points to the body of the letters. This connection is made by a unique straight and very thin strip. Under this modification these letters exhibit more exploitable signatures. Finally, a lookup table for identification of the 28 letters is carried out.
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