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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.

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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.

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