Design and Analysis of Gain-Enhanced ZIM Superstrate-Based Antenna for RFID Reader Applications

Abstract

This article introduces a new high-gain linearly polarized (LP) antenna utilizing zero-index metamaterial (ZIM). The design comprises of a rectangular radiating patch and a $2\times 2$ square-shaped metamaterial (MTM) structure. Through the MTM, a zero-index antenna is created, fabricated, and tested. The realized gain of the suggested design is higher with the MTM due to ZIM's focusing effect. The overall dimensions of the antenna are $0.24{\lambda }_0\times 0.016{\lambda }_0$, where ${\lambda }_0$ is the free-space wavelength. The proposed antenna includes a ground plane measuring $0.49{\lambda }_0\times 0.49{\lambda }_0$. The antenna's gain has been observed to increase, approximately from 3.95 to 5.61 dBi. The successful completion of the propagation test under various conditions, along with a reading distance of 7 cm in the ISM band, validates the potential use of the structure as a short-range RFID reader. The suggested antenna, loaded with an MTM superstrate, offers a minimized overall thickness, particularly in comparison to the use of ZIM superstrates for enhancing the gain in antennas documented in previous literature.