Mir Sabbir Hossain

This study focuses on the development, simulation, and practical validation of a metal-only microstrip patch antenna and its array designed to increase gain. The antenna is specifically designed to meet the growing demand for reliable and efficient RFID systems in various fields, such as asset tracking, inventory management, and smart logistics. Our design utilizes a truncated patch with an air substrate to achieve high gain and circular polarization. The antenna's dimensions measure 468 × 188 × 31 mm³ and deliver impressive performance metrics, boasting a return loss |S11| of -18.21 dB and an estimated gain exceeding 10.6 dBi. These figures compare favorably with the simulated results, which indicate an |S11| of -20.8 dB and a total gain of 11.2 dBi. Our microstrip antenna array demonstrated consistent Circular Polarization quality throughout the radiation angle, with an Axial Ratio of less than 3 dB. This antenna has emerged as a compelling solution for UHF-band RFID technology to meet the demands of various real-world applications.

SO2, HCN, and Cl2 gases are extremely toxic and can present significant health hazards even at minimal amounts, including respiratory and neurological systems. Timely identification aids in averting exposure and alleviating possible health risks, particularly in industrial and densely populated regions. Moreover, these gases can contribute to environmental pollution; thus, their monitoring is essential for human safety and environmental preservation. This specification recommends employing a photonic crystal fiber (PCF) to construct a terahertz octagonal core and curved air hole sensor for the detection of SO2, HCN, and Cl2 in the THz region. We routinely evaluate the recommended framework numerically, utilizing the entire finite element method. In terms of Cl2, the recommended sensor has a larger numerical aperture of 0.2909 and a superior sensitivity of 99.58%. Furthermore, this simulation yields a reduced effective material loss equal to 0.0020 cm-1 with a 3.094×10-12dB/m confinement loss for this gas. This technology utilizes the distinctive interaction between THz vibrations and gas molecules, improving detection sensitivity at trace levels relative to other techniques. This type of sensor may have practical applications in chemical sensing, biosensing, and gas sensing. Doi: 10.28991/ESJ-2025-09-02-01 Full Text: PDF

ABSTRACT This research presents a novel square hollow‐core photonic crystal fibre (PCF) sensor designed for the detection of food‐grade oils in the terahertz (THz) frequency range. The sensor’s effectiveness is quantitatively evaluated using COMSOL Multiphysics, a sophisticated simulation tool that employs finite element methodology (FEM) to model complex interactions within the fibre structure. Simulation outcomes reveal that, under optimal geometric parameters, the proposed sensor achieves an exceptional relative sensitivity of 98.27% for various edible oils at an ideal frequency of 2.2 THz, significantly outperforming existing technologies. Additionally, the sensor exhibits minimal confinement loss of 1.428 × 10 −8 dB/m and a low effective material loss of 0.004246 cm −1 , facilitating accurate detection of slight refractive index variations related to the chemical compositions of different oils. This high sensitivity enables non‐destructive testing, allowing for the analysis of oils without compromising their composition or quality, thereby maintaining the integrity of food products. Ultimately, the proposed PCF sensor enhances food safety monitoring and paves the way for advanced applications in the food industry, ensuring consumers receive high‐quality products.

Wireless Local Area Network (WLAN) has been one of the great communications technology success stories of the past few years. IEEE's standardization of WLAN has been extended to a family of standards. IEEE 802.11g, based on Orthogonal Frequency Division Multiplexing (OFDM), is a very popular standard for its capability of high data rate communication up to 54Mbps at the 2.4 GHz Industrial, Scientific and Medical (ISM) band. As the number of consumer devices designed for the ISM band is getting higher, co-channel interference has been identified as the major hindrance to the performance of WLAN devices. In this paper, a method of combating co-channel interference employing smart antenna technique is presented. We employ the Minimum Mean Square Error (MMSE) criterion to perform beamforming. We present simulation results that demonstrate performance improvement at the presence of co-channel interference.