Theses, Dissertations & Reports

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    Concentric Square Shaped Split Ring Based Metamaterial Absorber for Microwave Dual Band Applications
    (International Islamic University Chittagong, 2024-02) Alam, Neyamul
    The primary aim of this investigation is to formulate a split-ring metamaterial absorber (MMA) designed in the configuration of a maze to demonstrate superior absorption efficiency. The effective absorption is facilitated by the well-crafted split cut of the resonator within the unit cell. This metamaterial absorber (MMA) is assembled using a unit cell featuring dimensions of 10mm and a substrate composed of FR4 material with a permittivity of 4.4. Within this electromagnetic metamaterial absorber (MMA), transverse electromagnetic (TEM) mode is employed for electromagnetic waves, both under normal and oblique angles of incidence. The utilized maximum angles of incidence are 80° and 180°, respectively. Consequently, the MMA attains absorption rates of 93.70%, 93.32%, 99.96%, and 96.04% at four distinct resonant frequencies. Operating as a single negative (SNG) metamaterial absorber, the design resonates at frequencies of 4.44GHz, 6.24GHz, 8.50GHz, and 11.50GHz within the C and X bands. This proposed metamaterial design opens up possibilities for applications in radar absorption, wireless communication, microwave imaging, and radio astronomy
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    Fan Grill Shaped Circular Split-ring Loaded Metamaterial Absorber For X,K & Ku Band Applications
    (International Islamic University Chittagong, 2024-02) Hossain, Kazi Md Maharaz
    This thesis presents a Fan grill shaped circular split-ring loaded metamaterial absorber for X,K & Ku band applications. The finding demonstrates that regardless of the substrate or polarization angle, the TEM mode absorption rate is constant. With maximum absorptions of 99%, 98%, 99%, 92%, and 99%, respectively, the study shows five resonance gains in the X, K and Ku bands with single negative (SNG) MM characteristics at frequencies of 8.903094, 14.102, 14.606, 20.996, and 21.68 GHz. Due to its superior absorption qualities and clear construction compared with recent work on MM, this absorber has a special function in satellite communication, terrestrial microwave communication and radar communication, comparable works using FR4 substrate
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    Gas Stove Burner Shape with Inductive Tailed Rotational Symmetric Metamaterial Absorber for C and X Band Application
    (International Islamic University Chittagong, 2024-02) Chowdhury, Apurba Ray
    In this study, a multiband metamaterial (MM) absorber is shown. This absorber demonstrates the properties of the metamaterial at each resonance frequency. In the X band, absorption may be performed throughout the frequency spectrum between 10.373 and 10.825 gigahertz. At the frequencies of 4.12, 5.776, 10.472, and 10.696 GHz, where the maximum absorptions are respectively 99.4%, 99.9%, 95%, and 90.4%, four resonances gain in frequency in the C and X bands that have single negative (SNG) MM characteristics. These resonances occur at frequencies. In conclusion, compared with current work on MM, the highest angle sensitivity in Transverse Electromagnetic (TEM) mode, broadband absorption, and small size identify it as a more effective ideal absorber
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    Eye Shaped Labyrinth Metamaterial Absorber For C, X, Ku & K Band Applications.
    (International Islamic University Chittagong, 2024-02) Mahamud, Sayed
    In the microwave frequency domain, we introduce a simple design aimed at designing a multiband polarization-insensitive MA. Polarization-insensitive MA are currently highly appealing owing to their distinctive absorption characteristics across various polarization angles. This design involves imprinting a specific structure onto a metal-backed dielectric substrate Fr-4, which comprises an eye-shaped labyrinth structure. Upon conducting a series of diverse analyses at an angle of incidence perpendicular to the surface, it has been determined that the proposed arrangement exhibits significant levels of absorption, reaching 94.93% at frequencies of 5.76 GHz, 97.73% at frequencies of 7.432 GHz, 95.89% at frequencies of 10.644 GHz, 98.28% at frequencies of 13.813 GHz, 93.18% at frequencies of 19.048 GHz, 98.72% at frequencies of 21.006 GHz, 99.9% at frequencies of 22.856 GHz, 91.85% at frequencies of 23.756 GHz, and 99.15% at frequencies of 24.746 GHz. To gain deeper insights into the absorption mechanism intrinsic to this design, provide visualizations of surface current distributions.
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    Highly Sensitive Photonic Crystal Fiber Gas Sensor for Toxic Gases Detection in the Terahertz Regime
    (International Islamic University Chittagong, 2023-09) Nasif, Mohammad Abrar
    A form of optical fiber known as PCF uses the photonic crystal feature to its advantage. The quantitative effect of guiding characteristics on material properties along wavelength is examined using the finite element method (FEM). By employing the finite element method, Gas sensors made of photonic crystal fiber (PCF) can detect a variety of dangerous chemicals across a broad spectrum of wavelengths. The relative sensitivity, confinement loss, effective area, effective material loss, and dispersion are some of the sensing metrics obtained for various hazardous gases by means of this gas sensor. The hazardous gases we analyzed for our sensor investigation encompass Benzene (C6H6), Methyl Bromide (CH3BR), Tin Chloride (SnCL4), Sulfur Trioxide (SO3), and Vinyl Chloride (C2H3CL). The sensitivity of the proposed PCF for different gases like C6H6, CH3BR, SnCL4, SO3, and C2H3CL at the wavelength of 0.8 THz are 96.899%, 97.256%, 96.573%, 97.072%, and 96.961%. The effective material loss is about 0.009233, 0.015593, 0.00841, 0.016458, 0.01691 cm-1 and at the same wavelength confinement loss are 5.88 × 10−21, 3.36 × 10−17, 6.67 × 10−17, 6.44 × 10−22, and 9.42 × 10−17 dB/cm for C6H6, CH3BR, SO3, SnCL4, and C2H3CL. Due to its high sensitivity and uncomplicated construction, the suggested sensor has the potential to be used in significant ways for detecting biochemical and biological analytes.
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    Performance Analysis of Dense Wavelength Division Multiplexing System Based on Free Space Optics Communication
    (International Islamic University Chittagong, 2024-02) Injamam, Asiful Hoque
    This study reported the performance evaluation of various distributors and exchange elements configurations in the optical fiber communication system. With the increasing demand for high-speed data transfer, Dense Wavelength Division Multiplexing (DWDM) technology has become an attractive solution for optical communication systems. This paper presents the performance analysis of a DWDM-FSO-based on Free space optical communication system. The system consists of multiple channels, each transmitting data at a different wavelength, which are combined into a single optical fiber using a multiplexer. A demultiplexer separates the channels at the receiving end, and each channel's data is recovered separately. We analyze the performance of the system by measuring its bit error rate (BER) and Q-Factor (Quality Factor) under different channel. We also examine how varying the channel number affects the system's performance. Our results demonstrate that the proposed system can achieve high data rates and excellent performance with low BER and high Q-Factor (Quality Factor), making it a promising compressional evaluation for high-speed optical communication systems
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    Design And Simulation Of Dense Wavelength Division Multiplexing System For Different Channel On Free Space Optical Communication.
    (International Islamic University Chittagong, 2024-02) Talha, Abu
    This study reported the performance evaluation of various distributors and exchange elements configurations in the optical fiber communication system. With the increasing demand for high-speed data transfer, Dense Wavelength Division Multiplexing (DWDM) technology has become an attractive solution for optical communication systems. This paper presents the performance analysis of a DWDM-FSO-based on Free space optical communication system. The system consists of multiple channels, each transmitting data at a different wavelength, which are combined into a single optical fiber using a multiplexer. A demultiplexer separates the channels at the receiving end, and each channel's data is recovered separately. We analyze the performance of the system by measuring its bit error rate (BER) and Q-Factor (Quality Factor) under different channel. We also examine how varying the channel number affects the system's performance. Our results demonstrate that the proposed system can achieve high data rates and excellent performance with low BER and high Q-Factor (Quality Factor), making it a promising compressional evaluation for high-speed optical communication systems
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    An Improved Positioning System for 6G Cellular Network
    (International Islamic University Chittagong, 2024-02) Sifat, Md. Zahidul Islam
    Information about the whereabouts of oneself or our cell phones has always been crucial to humans. Technological advancements have supported us across various domains, spanning from interior environments to outdoor global positioning systems. However, achieving real-time indoor positioning has remained a formidable task. The requirement for enhanced positioning has gained prominence in the context of the emergence of 6G cellular networks. The introduction of novel radio technologies, characterized by reduced end-to-end latency, specialized control protocols, and increased processing capacity at the network edge, has opened doors to harnessing the 6G cellular network’s full potential for precise localization in indoor and outdoor settings. Within the 6G cellular network context, this study successfully implemented the classic signal fingerprinting approach using the Received Signal Strength Indicator in a combination with machine learning algorithms. Consequently, it proposed an improved positioning strategy designed for indoor localization scenarios in the next 6G cellular network environment. Using this method, with two datasets, the mean error distance of 0.08025523, meaning an accuracy of 99.92% and 0.10692412 was achieved, which is 99.89% accuracy respectively.
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    Enhanced Localization Infrastructure for 6G Cellular Network
    (International Islamic University Chittagong, 2024-02) Islam, Md. Aminul
    Information about the whereabouts of oneself or our cell phones has always been crucial to humans. Technological advancements have supported us across various domains, spanning from interior environments to outdoor global positioning systems. However, achieving real-time indoor positioning has remained a formidable task. The requirement for enhanced positioning has gained prominence in the context of the emergence of 6G cellular networks. The introduction of novel radio technologies, characterized by reduced end-to-end latency, specialized control protocols, and increased processing capacity at the network edge, has opened doors to harnessing the 6G cellular network’s full potential for precise localization in indoor and outdoor settings. Within the 6G cellular network context, this study successfully implemented the classic signal fingerprinting approach using the Received Signal Strength Indicator in a combination with machine learning algorithms. Consequently, it proposed an improved positioning strategy designed for indoor localization scenarios in the next 6G cellular network environment. Using this method, with two datasets, the mean error distance of 0.08025523, meaning an accuracy of 99.92% and 0.10692412 was achieved, which is 99.89% accuracy respectively.
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    Design and Microscript Path Antenna for Brain Tumor Detection
    (International Islamic University Chittagong, 2024-03) Chowdhury, Prapon
    This paper introduces a compact Iarable rectangular-shaped microstrip patch antenna designed for brain tumor detection in the ISM band (2.4-2.4835 GHz). The antenna measures 60 x 40 mm and employs an FR-4 dielectric substrate (1.6 mm thick) with copper for the patch and ground (0.035 mm thick) To enhance accuracy, a human head phantom model is created with six homogeneous layers representing the head's components: skin, fat, skull, dura, CSF (Cerebrospinal fluid), and the brain. A benign tumor with a 5 mm diameter is simulated in the model. The antenna transmits an input signal into the phantom and records the response. It monitors magnetic field, electric field and return loss for both a normal head model and one with the 5 mm benign tumor, ensuring these parameters meet ISM band safety criteria. In accordance with IEEE safety standards, the Specific Absorption Rate (SAR) within the brain must not exceed 1.6 W/kg. The designed model achieves a SAR, confirming its safety for human use.