Dual-Band Circularly-Polarized Unidirectional Patch Antenna for RFID Reader Applications

Abstract

A dual-band 0.92/2.45 GHz circularly-polarized (CP) unidirectional antenna using the wideband dual-feed network, two orthogonally positioned asymmetric H-shape slots, and two stacked concentric annular-ring patches is proposed for RF identification (RFID) applications. The measurement result shows that the antenna achieves the impedance bandwidths of 15.4% and 41.9%, the 3-dB axial-ratio (AR) bandwidths of 4.3% and 21.5%, and peak gains of 7.2 dBic and 8.2 dBic at 0.92 and 2.45 GHz bands, respectively. Moreover, the antenna provides stable symmetrical radiation patterns and wide-angle 3-dB AR beamwidths in both lower and higher bands for unidirectional wide-coverage RFID reader applications. Above all, the dual-band CP unidirectional patch antenna presented is beneficial to dual-band RFID system on configuration, implementation, as well as cost reduction.Index Terms-Dual-band, circularly-polarized (CP), patch antenna, RF identification (RFID), axial-ratio (AR).

A Jia-shaped artistic patch antenna for dual-band circular polarization

“…Circularly polarized (CP) antennas have been widely installed in modern communication systems due to their anti-fading and antiinterference abilities in a multipath, dense environment. In the past decades, numerous antennas were proposed for dual-band CP operations [13][14][15][16][17][18][19]. In 2001, a dual-band CP radiation was achieved by inserting four T-shaped slits at the edges of a single-feed square patch [13].…”

“…In [16], a rotated rectangular patch stacked with a circular patch excited by aperture feed was presented for dual-band CP (2.26/2.67-GHz) operation. A dual-band (0.92/2.45-GHz) RFID antenna comprises two stacked ring-patches excited by a hybrid complicated feed network was introduced [17]. Moreover, an EBG resonator antenna was proposed for dual-band CP (9.65/11.75-GHz) operation [18].…”

Dual-Band RFID Antenna for 0.92 GHz Near-Field and 2.45 GHz Far-Field Applications

“…Most of the dual-band antennas are applied for far-field operation mode whereas most of the dual mode antennas are operated at the same frequency [19][20][21]. In [21], the dual-band 0.92/2.45 GHz unidirectional CP antenna is presented employing multiloops and a complex power splitter, but the operation modes of these two frequencies are all far field. In [22], the antenna can be operated in both near-field and far-field modes at a UHF band.…”

Near‐field UHF L‐shaped dipole antenna array with LC‐balun integration for item‐level tagging systems

“…For efficient inventory management, many reader antennas which have not only high gain characteristic but compact size have been presented. 1,2 Moreover, demand of near-field RFID solutions for item-level tagging in a shop, a hospital, and a factory is increasing recently because the solutions economize unnecessary working time and personnel expenses. For itemlevel tagging in a specific area, near-field RFID antennas are needed.…”