Dual-band circularly polarized flat antenna with plano convex and concave slots for RFID readers

Abstract

This article has proposed a circularly polarized dual‐band antenna with unidirectional pattern operating at the bandwidth frequencies of 920–925 MHz and 2.40–2.48 GHz for radiofrequency identification (RFID) readers. The proposed antenna structure is of a radiating patch with a single feeder and two pairs of plano convex and concave slots. This work has innovated and utilized the convex and concave slotting technique to generate the circular polarization. The simulated results showed that the dual‐band antenna is of circular polarization (CP) and unidirectional radiation pattern with the 3 dB axial ratio and the respective gains of 1.31 and 1.36 dBic for the experimental lower and upper bandwidth frequencies. An antenna prototype was subsequently fabricated and tests performed. The simulated and measured results are in good agreement, rendering the proposed dual‐band antenna with plano convex and concave slots suitably applicable to the ultrahigh frequency and microwave RFID readers.

Substrate effect and structure optimization of fabric-based circularly polarized dipole antenna for radio frequency energy harvesting

“…The prepared fabricbased CP antenna has a wider bandwidth compared with other research. 15,18,[49][50][51][52] However, as no reflector is designed on the back of the antenna, which improves its radiation performance, the gain of the proposed fabric antenna is lower than the reference. 15 Although the previous antenna in Bajaj et al 52 has a wide bandwidth, the substrate of the antenna is a hard FR4 substrate, which is not suitable for the wearable field.…”

Linearly tapered meander line cross dipole circularly polarized antenna for UHF RFID tag applications

“…Read range can also be enlarged by removing the polarization mismatch between the reader and the tag antennas. Since most UHF RFID systems employ linearly polarized (LP) tag antenna, circularly polarized (CP) antenna is used for reader applications to increase the reliability of detection of arbitrarily oriented tag antenna . Due to the polarization mismatch, only half of the transmitted power from the CP reader antenna is received by the LP tag antenna.…”

“…Since most UHF RFID systems employ linearly polarized (LP) tag antenna, 3,4 circularly polarized (CP) antenna is used for reader applications to increase the reliability of detection of arbitrarily oriented tag antenna. 5,6 Due to the polarization mismatch, only half of the transmitted power from the CP reader antenna is received by the LP tag antenna. The polarization efficiency can be increased by using circularly polarized tag antenna instead of linearly polarized tag antenna.…”