Abstract
This paper presents a compact circularly polarized microstrip antenna for radio frequency identification (RFID) readers. The dimensions of the proposed antenna are reduced by etching a cross slot in the radiation patch and loading four grounded coupling patches on the four corners of the radiation patch. An inverted Z-shaped coupling feedline is used to realize circularly polarized operation. The measured -10 dB |S11| bandwidth, 3-dB axial ratio bandwidth and maximum gain are 872-1095 MHz, 888-933 MHz, and 5.52 dBi, respectively, at 922 MHz frequency. The overall dimension of the proposed antenna is 0.36 λ g X 0.36 λ g X 0.05 λ g (λ g is the guide wavelength at the center frequency of 915 MHz). The proposed antenna has small size with good overall performance and is suitable for compact RFID devices.
Highlights
Radio frequency identification (RFID) is a wireless communication technology that uses electromagnetic waves to transmit and exchange information, and has been widely used in tracking of goods, manufacturing, supply chain, industry, and commerce
The simulated and measured results are in good agreement and both can completely cover the entire operating bandwidth of ultrahigh frequency (UHF) RFID
This paper presents a compact circular polarization unidirectional antenna for RFID readers
Summary
Radio frequency identification (RFID) is a wireless communication technology that uses electromagnetic waves to transmit and exchange information, and has been widely used in tracking of goods, manufacturing, supply chain, industry, and commerce. Compact planar microstrip patch antennas are widely used in RFID systems because of their low profile, easy construction, and simple structure Many techniques, such as using a substrate with high dielectric permittivity [2], slotting the radiation patch [3], and loading shorting probe [4], [5], have been developed to miniaturize microstrip antennas. Frequency selective surface layers offer reflective phase coherence in broadband to achieve good antenna performance [17] These techniques provide unidirectional radiation patterns they experience the same problem, that is, the reflector structure is complex with extremely large size. Compared with [15]–[17], a simple resonance-based reflector structure is proposed to provide unidirectional radiation in broadband, but it cannot reduce the profile height [18], [19]. The proposed antenna has smaller size, lower axial ratio (AR), and wider bandwidth compared with other microstrip structures with air gap [20], [21]
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