Design of Dual-Band Circularly Polarized Stacked Patch Antenna for RFID Applications

This article presents a novel dual-band circularly polarized sector antenna operating at 900 MHz and 5.9 GHz, intended for Radio Frequency Identification (RFID) applications. It consists of four sectorial patches and a feeding network with two substrates stacked one over another. From the four sectorial patches, two patches are excited by aperture coupling and the remaining two are the parasitic patches coupled from the main patch. The feeding networks are designed using 90° phase offset to achieve circular polarization. The main radiating patches are excited by using the slots on the bottom substrate. The presented antenna has radiating bandwidths of 547 MHz and 447 MHz ranging from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$647-1194 \text{MHz}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5.82-6.26 \text{GHz}$</tex>, respectively. The simulated peak gain values are 12 dBi and 9 dBi, while the average gain values are 11.8 dBi and 8.8 dBi at 900 MHz and 5.9 GHz, respectively. The proposed antenna also exhibits axial ratio (AR) bandwidths of 0.84 GHz at 900 MHz and 0.54 GHz at 5.9 GHz. These performance characteristics indicate that the antenna is well-suited for deployment in RFID systems, as well as vehicular and WLAN communication applications.