This paper presents a Circularly Polarized Microstrip Patch Antenna (CPMPA) miniaturization with parasitic elements, suitable for UHF RFID systems. The antenna consists of a half E-shaped patch with cuts. A truncated corner patch can generate an additional Circular Polarization (CP) radiation mode and further enhance the axial ratio. Two symmetric cross shaped slots along the horizontal axis of the CPMPA have been embedded, and its dimension optimization has been based on parametric analysis. Thanks to this slotted structure and reduced surface area, good CP quality has been obtained with a 25% overall size reduction. The proposed antenna is lightweight, low profile, simple, and easily produced. The structure’s simulation is made using CST Studio Suite 2014 to compute return loss (S11), gain, and the axial ratio of the antenna while the overall miniaturized antenna’s volume is 77mm×58mm×1.6mm operating at 915MHz.

This paper presents a new circular monopole antenna with triple-band characteristics that can operate in both ultra-high frequency (UHF) and ultra-wideband (UWB) and can be integrated into a radio-frequency identification (RFID) system reader board. The antenna was built with a patch and a coplanar waveguide (CPW) feed microstrip line to meet the UHF/UWB bandwidth requirements for RFID applications. The designed antenna has a size of 70 mm × 60 mm × 0.8 mm. CST Microwave Studio simulations were used to validate the proposed antenna, which had a maximum gain of 4.8 dBi. Furthermore, the designed antenna had a radiation pattern that spanned the full working band. To interact with RFID tags, the antenna was built and installed into the RFID reader board. The simulation and measurement findings showed good agreement. Experiments indicated that the UHF-RFID performance of the monopole antenna was comparable to that of existing commercial solutions.

A novel methodology is proposed to reliably predict the resonant characteristics of a multipatch backscatter-based radio frequency identification (RFID) chipless tag. An ultra-wideband impulsion radio (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and analyzes the obtained backscatter in the time domain. The RFID system consists of a radar cross-section (RCS)-based chipless tag containing a square microstrip patch antenna array in which the chipless tag is interrogated with a UWB pulse by an UWB-IR-based reader. The main components of the backscattered signal, the structural mode, and the antenna mode were identified and their spectral quality was evaluated. The study revealed that the antenna-mode backscatter includes signal carrying information, while the structural mode backscatter does not include any tag information. The simulation findings were confirmed by experimental measurements obtained in an anechoic chamber environment using a 6-bit multipatch chipless RFID tag. Finally, the novel technique does not use calibration tags and can freely orient tags with respect to the reader.

Chipless RFID has the potential to bring in a paradigm change in industrial applications, notably in the world of the Internet of Things (IoT). This wireless technology permits distant identification, sensing, and tracking, giving tremendous development prospects. Despite substantial advances over the previous century, designing high-performance chipless RFID for IoT applications remains a problem. This research presents a new chipless planar RFID tag for item tracking and identification in IoT systems. The suggested tag uses numerous T-shaped slow-wave structures as micro-reflecting resonators with different dimensions on a lossy substrate to encode information in the tag’s backscattered signal after illumination. The mutual coupling between the resonators has been minimized to improve tag performance and printing variety. A tag with a coding capacity of 24 bits and a compact size of 60 x 40 mm ² was simulated in CST Microwave Studio to validate the suggested approach. To create tags, several patterned configurations were applied on a Rogers RO4350B substrate, and their radar cross-section responses were studied. When compared to typical multi-resonator tags, the suggested tag design demonstrated excellent downsizing and efficient frequency spectrum usage. Furthermore, the Q-factor and coding strength were both high, showing that the suggested technology is capable of manufacturing high-performance chipless tags.

In order to encrypt/encode data based on the magnitude level of the radar cross-section (RCS), we propose an approach with a precise estimation considering the resonant characteristics of a multipatch backscatter-based chipless radio frequency identification (RFID) dedicated for chipless tags depolarization. The working principle is based on the polarization mismatch between the tag and the reader antenna to control the magnitude of the backscatter, which allows a reliable detection in real environments. We introduce in this paper a new 4-bit chipless RFID tag with an enhanced RCS, based on a triangular patch antenna with multiple resonators. Additionally, we propose an ultra-wideband impulse radar (UWB-IR)-based reader that interrogates the chipless tag with a UWB pulse, and the received backscatter was studied in both time- and frequency-domains. The antenna was operating from 4.7 to 6.1 GHz, a band allocated for RFID systems. The obtained experimental measurement results in the environment of anechoic chamber were exceptionally relevant to validate the simulation results.

This paper focuses on the basic concepts of chipless Radio Frequency IDentification (RFID) tag at 30 GHz destined for short range applications. Chipless RFID is proposed as the solution for low cost item tagging. The chipless tag encodes data into the spectral signature using a multiresonator. Both amplitude and phase components of the spectral signature are used for data encoding. The chipless RFID tag is a prototype and comprises of a microstrip multiresonating circuit with 6 spiral resonators and two cross-polarized transmitting and receiving circular UWB monopole antennas. Commercial based software, the finite-integration technique is used to investigate the characteristics of the chipless RFID tag.