Search

This paper aims to produce a high data capacity and miniaturized flexible chipless RFID tag based on the frequency signature using the Modified Complementary Split Ring Resonator (MCSRR). The proposed 19 bits chipless RFID tag using the frequency shifting technique consists of five slotted overlaying MCSRR with Different Width (MCSRR with DW) structures and the dimension of 48 mm × 48 mm. The structure is designed by using a flexible (Polyethylene Terephthalate) PET substrate with permittivity of 0.2. The operating frequency is between 0.9 GHz and 2.7 GHz. The advancement of slotted overlaying MCSRR with DW structures has successfully miniaturized the chipless RFID tag structure to about 107 mm2/ bit, 0.02λmid2/bit and 0.09 GHz/bit by maximizing the number of resonators in a limited space and minimizing the frequency separation between the resonators. The omnidirectional tag antenna is incorporated with the proposed MCSRR structure using the retransmission measurement method. The log-periodic antenna with a gain of 5-7 dBi is used for this measurement to improve the range distance between tag and reader system. Based on the retransmission measurement involving the antenna tag, the 19 bits chipless RFID tag which consists of five MCSRR with DW structures can be detected with a maximum range distance of 30 cm and a power transmitted level of 30 dBm.

The detection of partial discharge (PD) activities in high-voltage equipment can be conducted according to several mechanisms of signal detection, including electromagnetic wave signal detection, acoustic signal detection, chemical reactions, electrical signal detection, and optical emission detection. Recently, multiple methods of detection and localization of partial discharge activities, which occurred in power transformers and gas-insulated switchgear (GIS), have been proposed to monitor the health condition of high-voltage equipment, especially when the awareness regarding preventive maintenance has been emphasized at the industrial level and among electrical providers. In aligning the needs of the industrial sector and the improvement of PD-detection methods, this manuscript focuses on reviewing the current practice methods for the detection and localization of PD signals in high-voltage equipment, comparing their efficacy, and summarizing the future direction of research work-related methods of PD detection. The comparative reviews are discussed in terms of the mechanism of PD signal detection, indication parameters, calibration techniques, and the advantages and limitations of each method of PD measurement in detail.

A low-profile and wide-angle radiation pattern reconfigurable antenna is designed, analyzed, and fabricated for wireless sensor network (WSN) applications, which operate at a 2.5-GHz frequency. This work aims to minimize the number of switches and optimize the parasitic size and ground plane to achieve a steering angle of more than 30° using a low cost-high loss FR-4 substrate. The radiation pattern reconfigurability is achieved by introducing four parasitic elements surrounding a driven element. In this work, the single driven element is fed by a coaxial feed, while other parasitic elements are integrated with the RF switches on the FR-4 as the substrate with dimensions of 150 × 100 mm (1.67 × 2.5 λo). The RF switches of the parasitic elements are surface mounted on the substrate. By truncating and modifying the ground plane, the beam steering can be achieved at more than 30° on the xz plane. Additionally, the proposed antenna can attain an average tilt angle of more than 10° on the yz plane. The antenna is also capable of attaining other important results, such as a fractional bandwidth of 4% at 2.5 GHz and an average gain of 2.3 dBi for all configurations. By adopting the ON/OFF condition on the embedded RF switches, the beam steering can be controlled at a certain angle, thus increasing the tilting angle of the wireless sensor networks. With such a good performance, the proposed antenna has high potential to serve as a base station in WSN applications.

In this paper, the design, simulation, fabrication, and characterization study of a low-cost and directional hybrid four-element (2 × 2 configuration) Minkowski–Sierpinski fractal antenna array (MSFAA) for the high-efficiency IEEE 802.11ax WLANs (Wi-Fi 6E) and the sub-6 GHz 5G wireless system is presented. Each element of the array is separated by 0.7 λ0. The complete four-element fractal antenna array system includes designing the single-element Minkowski–Sierpinski fractal antenna using two different substrates for performance comparison and an equal-split Wilkinson power divider (WPD) to achieve power division and to form a feed network. The single-element antenna, four-element fractal antenna array, and WPDs are fabricated using a flame-resistant (FR4) glass epoxy substrate with a dielectric constant (εr) of 4.3 and thickness (h) of 1.66 mm. For performance comparison, a high-end Rogers thermoset microwave material (TMM4) substrate is also used, having εr = 4.5 and h = 1.524mm, respectively. The designed four-element fractal antenna array operates at the dual-band frequencies of 4.17 and 5.97 GHz, respectively. The various performance parameters of the antenna array, such as return loss, bandwidth, gain, and 2D and 3D radiation patterns, are analyzed using CST Microwave Studio. The fabricated four-element antenna array provides the bandwidth and gain characteristic of 85 MHz/4.19 dB and 182 MHz/9.61 dB at 4.17 and 5.97 GHz frequency bands, respectively. The proposed antenna array design gives an improvement in the bandwidth, gain, and radiation pattern in the boresight at both frequencies. In the IEEE 802.11 ax WLANs (Wi-Fi 6E) deployments and the upcoming 5G wireless and satellite communication systems, it is critical to have directional antenna arrays to focus the radiated power in any specific direction. Therefore, it is believed that the proposed dual-band four-element fractal antenna array with directional radiation patterns can be an ideal candidate for the high-efficiency IEEE 802.11ax WLANs (Wi-Fi 6E) and the upcoming 5G wireless and satellite communication systems.

A compact triple-band operation ultra-wideband (UWB) antenna with dual-notch band characteristics is presented in this paper. By inserting three metamaterial (MTM) square split-ring resonators (MTM-SSRRs) and a triangular slot on the radiating patch, the antenna develops measured dual-band rejection at 4.17–5.33 GHz and 6.5–8.9 GHz in the UWB frequency range (3–12 GHz). The proposed antenna offers three frequency bands of operation in the UWB range, which are between 3–4.17 GHz (~1.2 GHz bandwidth), 5.33–6.5 GHz (~1.17 GHz bandwidth), and 8.9–12 GHz (~3.1 GHz bandwidth), respectively. The higher resonating frequency band can be tuned/controlled by varying the width of the triangle slot, while the medium operational band can be controlled by adjusting the width of the SSRR slot. Initially, the simulated S-parameter response, 2D and 3D radiation patterns, gain, and surface current distribution of the proposed UWB inverted triangular antenna has been studied using epoxy glass FR4 substrate having parameters εr = 4.3, h = 1.6 mm, and tan δ = 0.025, respectively. In order to validate the simulation results, the proposed UWB antenna with dual-notch band characteristics is finally fabricated and measured. The fabricated antenna’s return-loss and far-field measurements show good agreement with the simulated results. The proposed antenna achieved the measured gain of 2.3 dBi, 4.9 dBi, and 5.2 dBi at 3.5 GHz, 6.1 GHz, and 9.25 GHz, respectively. Additionally, an in-depth comparative study is performed to analyze the performance of the proposed antenna with existing designs available in the literature. The results show that the proposed antenna is an excellent candidate for fifth-generation (5G) mobile base-stations, next-generation WiFi-6E indoor distributed antenna systems (IDAS), as well as C-band and X-band applications.

In this article, two distinct kinds of metamaterial (MTM) antennas are proposed for fifth-generation (5G) indoor distributed antenna systems (IDAS). Both antennas operate in the sub-6 GHz 5G band, i.e., 3.5 GHz. The antenna’s radiating structure is based on a combination of triangular and rectangular patches, as well as two complementary split-ring resonators (CSRR) unit-cells etched on the top layer. The bottom layer of the first MTM antenna is a complete ground plane, while the bottom layer of the second MTM antenna is etched by a 3 × 3 cross-slot MTM structure on the ground plane. The use of these structures on the ground plane improves the antenna bandwidth. The proposed antennas are designed using two different substrates i.e., a high-end Rogers thermoset microwave materials (TMM4) substrate (h = 1.524 mm/εr = 4.5/tan δ = 0.002) and a low-end flame-resistant (FR4) epoxy glass substrate (h = 1.6 mm/εr = 4.3/tan δ = 0.025), respectively. The antenna designs are simulated using CST microwave studio, and in the end, the antenna fabrication is performed using FR4 substrate, and the results are compared. Furthermore, parametric analysis and comparative studies are carried out to investigate the performance of the designed antennas. The simulated and measured results are presented for various parameters such as return-loss, gain, and radiation pattern. The two MTM antennas have an overall dimension of 18 × 34 mm2, demonstrating that the proposed design is 60 percent smaller than a standard microstrip patch antenna (MPA). The two proposed MTM antenna designs with complete ground plane and 3 × 3 cross-slot MTM on the bottom layer using FR4 substrate have a measured gain/bandwidth characteristic of 100 MHz/2.6 dBi and 700 MHz/2.3 dBi, respectively.