This article describes the design of an Ultra-High Frequency (UHF) miniature folded dipole Radio Frequency Identification (RFID) tag antenna that can be mountable on metallic objects. The compact tag antenna is formed from symmetric C-shaped resonators connected with additional arms embedded into the outer strip lines for miniaturization purposes. It is loaded with outer strip lines, resulting in a flexible tuning method that is capable of matching the integrated circuit (IC) chip’s impedance. The proposed tag is fabricated on a single layer of Polytetrafluoroethylene (PTFE) substrate. It has simple structure and does not require any metallic vias or shorting plate. The miniature tag antenna with a size of 82.75 × 19.5 × 1.5   mm 3 yields a total realized gain of − 0.53   dB at the resonance frequency when attached to a 40 × 40   cm 2 metal plate. The presented design utilizes a European RFID band, and the simulated results of realized gain, read range, and input impedance are verified with measurement results.

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Transparent conductive oxides (TCOs) are widely integrated in the field of optoelectronics since they are optically transparent and electrically conductive at the same time. Indium tin oxide (ITO) is a well-developed TCO, but due to its high cost, aluminum zinc oxide (AZO) is now emerging as a promising low-cost replacement for ITO. This work reports on AZO thin film prepared with polyvinyl alcohol (PVA) as a host material. The AZO–PVA thin film was incorporated into an erbium-doped fiber laser (EDFL) as a saturable absorber for the first time. Both Q-switched and nanosecond pulse mode-locked operation were experimentally achieved. The Q-switched EDFL operated at the center wavelength of 1559.6 nm, which had the shortest pulse width of 2.2 µs, the maximum repetition rate of 86 kHz and the highest pulse energy of 47.3 nJ. The mode-locked was achieved at the center wavelength of 1560.4 nm.

This study presents a novel miniature ultra-high frequency (UHF) radio frequency identification (RFID) tag for metallic objects. Its arrangement includes a U-shaped feeder, which is inductively coupled to two E-type connected patches. Size reduction is achieved by means of utilizing the U-shaped feeder, and introducing a defection in the connection between the two E-type patches. The defection in the connection area between the patches modifies the current distribution by increasing the electrical length, and the antenna inductance. Furthermore, increasing the length of the U-shaped structure significantly raises the antenna inductance and, consequently, the flexibility of the structure for the impedance matching purpose. Polytetrafluoroethylene (PTFE) is employed for the fabrication of the designed tag. The tag's size is 65 mm × 20 mm × 1.5 mm, and does not require any complex fabrication process such as utilization of metal vias and/or shorting stubs. It is observed that with 4W EIRP, the measured detection distance is 6.9 m when it is attached onto metal sheets (20 cm × 20 cm), and 5.54 m when it is in free space. The measurement results also are in good agreement with the simulated results.INDEX TERMS Defected microstrip surface, impedance matching, metal mountable tag antenna, miniature UHF tag antenna.

A metal mountable UHF RFID tag antenna with a low-profile folded dipole structure is proposed. It is fabricated on a single layer of polytetrafluoroethylene (PTFE) dielectric laminate. It is composed of two symmetrical C-shape resonators integrated with the outer strip lines. The IC chip's terminals are connected directly to the center of the C-shaped resonators. The outer strip lines are integrated with the C-shaped resonators, which function to lower the reflection coefficient so as to match the IC chip impedance. In particular, the outer strip lines increase the inductive reactance of the antenna impedance in order to realize IC chip impedance. The design has a simple structure, due to the fact that it lacks any metallic vias. Moreover, the gain of the tag antenna can be enhanced when positioned on a large metallic sheet. Installed on a 40 × 40 cm 2 metallic plate, the total gain of the proposed tag antenna is 3 dB, with a maximum reading range of 5.77 m, while it is 3.92 m in free space. The simulation results were in excellent agreement with the fabricated design results.