Design of a novel dual ports antenna to enhance sensitivity of handheld RFID reader

A compact dual ports antenna with high isolation is proposed for handheld radio frequency identification (RFID) reader which is rarely reported in open literatures. Different with conventional handheld RFID reader antennas with single port, the proposed antenna transmits and receives signal separately. The proposed antenna operating with full duplex mode can enhance effectively sensitivity of reader, since the strong transmitting signal of reader with single port is usually highly coupled with weak receiving backscatter signal of tag. The antenna utilizes E-shaped aperture-coupled patch structure that occupies less volume and provides further space-saving efficiency. The height of the proposed antenna is only 6.8 mm and the volume of that is 80 mm × 80 mm × 6.8 mm, which is easy to integrate in handheld RFID readers. The antenna uses two E-shaped coupling apertures to excite two orthogonal modes for dual-polarized operation. High isolation of around −30 dB is obtained by proper arrangement of the length of coupling apertures and the position of the stubs. The measured results show −10 dB matching band and −25 dB isolation band from 2.32 to 2.6 GHz and from 2.3 to 2.55 GHz, respectively. The antenna is suitable for applications in handheld RFID readers.

Miniaturized Dual Band Multislotted Patch Antenna on Polytetrafluoroethylene Glass Microfiber Reinforced for C/X Band Applications

This paper introduces a new configuration of compact, triangular- and diamond-slotted, microstrip-fed, low-profile antenna for C/X band applications on polytetrafluoroethylene glass microfiber reinforced material substrate. The antenna is composed of a rectangular-shaped patch containing eight triangles and two diamond-shaped slots and an elliptical-slotted ground plane. The rectangular-shaped patch is obtained by cutting two diamond slots in the middle of the rectangular patch, six triangular slots on the left and right side of the patch, and two triangular slots on the up and down side of the patch. The slotted radiating patch, the elliptical-slotted ground plane, and the microstrip feed enable the matching bandwidth to be widened. A prototype of the optimized antenna was fabricated on polytetrafluoroethylene glass microfiber reinforced material substrate using LPKF prototyping machine and investigated to validate the proposed design. The simulated results are compared with the measured data, and good agreement is achieved. The proposed antenna offers fractional bandwidths of 13.69% (7.78–8.91 GHz) and 10.35% (9.16–10.19 GHz) where S11< −10 dB at center frequencies of 8.25 GHz and 9.95 GHz, respectively, and relatively stable gain, good radiation efficiency, and omnidirectional radiation patterns in the matching band.

Photodegradation of Methyl Orange Using Magnetically Recoverable AgBr@Ag3PO4/Fe3O4Photocatalyst under Visible Light

A novel magnetically recoverable AgBr@Ag3PO4/Fe3O4hybrid was prepared by a simple deposition-precipitation approach and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy (DRS). The results revealed that the photocatalytic activity and stability of AgBr@Ag3PO4/Fe3O4composite toward decomposition of methyl orange (MO) dye were superior to those of pure Ag3PO4under visible light irradiation. The photocatalytic activity enhancement of AgBr@Ag3PO4/Fe3O4is closely related to the efficient separation of electron-hole pairs derived from the matching band potentials between Ag3PO4and AgBr, as well as the good conductivity of Fe3O4. Moreover, the photocatalyst could be easily separated by applying an external magnetic field due to its magnetic property. The quenching effects of different scavengers proved that active h+and played the major role for the MO degradation. This work would provide new insight for the construction of visible light responsible photocatalysts with high performance, good stability, and recoverability.