Abstract
We propose a flexible anti-metal radio frequency identification (RFID) tag antenna based on a high-conductivity graphene assembly film (HCGAF). The HCGAF has a conductivity of 1.82 × 106 S m−1, a sheet resistance of 25 mΩ and a thickness of 22 μm. The HCGAF is endowed with high conductivity comparable to metal materials and superb flexibility, which is suitable for making antennas for microwave frequencies. Through proper structural design, parameter optimization, semiautomatic manufacturing and experimental measurements, an HCGAF antenna could realize a realized gain of –7.3 dBi and a radiation efficiency of 80%, and the tag could achieve a 6.4 m read range at 915 MHz on a 20 × 20 cm2 flat copper plate. In the meantime, by utilizing flexible polyethylene (PE) foam, good conformality was obtained. The read ranges of the tags attached to curved copper plates with different bending radii were measured, as well as those of those attached to several daily objects. All the results demonstrate the excellent performance of the design, which is highly favorable for practical RFID anti-metal applications.
Highlights
Numerous antenna design solutions have been proposed to overcome this problem, such as an antenna based on an electromagnetic bandgap (EBG) [9,10] or artificial magnetic conductor (AMC) structure [11,12], a patch-style antenna including a planar inverted-F antenna (PIFA) [13,14], and a microstrip-slot antenna [15,16]
Instead of employing metallic via holes to connect to ground, a wrapped patch-slot antenna was put forward to obtain a realized gain of –7.3 dBi and a radiation efficiency of 80%, and our tag can successfully obtain an excellent read range of 6.4 m at 915 MHz on a 20 × 20 cm2 flat copper plate
Due to the low profile as well as usage of the high-conductivity graphene assembly film (HCGAF) and the flexible PE foam, the proposed tag shows a good advantage for conformal applications
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Numerous antenna design solutions have been proposed to overcome this problem, such as an antenna based on an electromagnetic bandgap (EBG) [9,10] or artificial magnetic conductor (AMC) structure [11,12], a patch-style antenna including a planar inverted-F antenna (PIFA) [13,14], and a microstrip-slot antenna [15,16] These existing designs can favor anti-metal application in many common application scenarios. Most of the existing flexible anti-metal tag antennas are made of aluminum foil (~10 μm), the performance of which dramatically deteriorates due to oxidation, corrosion and bending.
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