Saudi Cultural Missions Theses & Dissertations
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Item Restricted Compact High-Data-Rate Implantable Antennas for Leadless Cardiac Pacemakers(Saudi Digital Library, 2025-07-02) Alghamdi, Abdulwahab; Ben Mabrouk, IsmailIn recent years, biomedical telemetry has revolutionised healthcare by enabling real time remote monitoring of physiological parameters, reducing the need for frequent hospital visits and in-person check-ups. At the heart of this advancement are Im plantable Medical Devices (IMDs), which facilitate wireless monitoring for a range of critical applications, including endoscopy, blood pressure tracking, cardiac defibrilla tors, pacemakers, and blood glucose monitoring. Among these innovations, leadless pacemakers have gained significant attention due to their minimally invasive design and improved patient comfort. However, their effectiveness depends largely on a well-optimised implantable antenna, which is essential for ensuring reliable wireless communication. This thesis focuses on addressing key challenges including miniaturisation, res onant frequency detuning, and multipath fading within the human body’s lossy electromagnetic environment. Three novel implantable antenna designs are presented in this work. The first contribution presents an implantable antenna with a rectangular patch design, incorporating a U-shaped slot, an inductive shorting pin, and multiple edge slots. It achieves a volume of 9.44 mm³, offering a 3.39 GHz bandwidth and a fractional bandwidth of 138%. The antenna supports a broad frequency range from 0.76 to 4.15 GHz, covering key medical bands, including the Industrial, Scientific, and Medical (ISM) bands at 0.869, 0.915, and 2.45 GHz; the Wireless Medical Telemetry Service (WMTS) band at 1.4 GHz; and the midfield communication band around 1.6 GHz. Simulation results within a homogeneous phantom (HP) of heart tis sue indicate gain values of −32.4 dBi at 0.915 GHz, −27.94 dBi at 1.4 GHz, and −19.8 dBi at 2.45 GHz. The second contribution presents an ultra-compact im plantable antenna featuring a central C-shaped slot. It has a volume of 8.33 mm³, a fractional bandwidth of 152.7%, and operates within a frequency range of 0.67 to 5 GHz, covering essential medical bands. These include the ISM bands at 0.915 GHz and 2.45 GHz, the WMTS band at 1.4 GHz, and the midfield band at 1.6 GHz. Simulation results indicate gain values of −31.3 dBi at 0.915 GHz, −25.8 dBi at 1.4 GHz, and −21.9 dBi at 2.45 GHz. The third contribution introduces a 2×1 ultra-wideband multiple-input, multiple-output (UWB-MIMO) antenna de signed with two loop radiators and a shared slotted ground plane. The antenna achieves a compact volume of 16.4 mm³, a wide fractional bandwidth of 165.12%, and operates from 710 MHz to 7438 MHz with a high isolation level of −21 dB. The individual MIMO antenna elements exhibit peak gain values of −34.7 dBi at 0.915 GHz, −28.4 dBi at 1.4 GHz, −23.3 dBi at 2.45 GHz, and −20.1 dBi at 5.8 GHz. Furthermore, at a signal-to-noise ratio (SNR) of 20 dB, the antenna achieves a channel capacity of 15.04 bps/Hz, highlighting its suitability for high-data-rate telemetry in next-generation leadless pacemakers. Specific Absorption Rate (SAR) analysis confirms that all three implantable antennas comply with regulatory safety standards, ensuring patient safety.11 0Item Restricted DESIGN OF A DUAL-BAND 900 MHz and 2.4 GHz RF-DC RECTIFIER AND DC-DC BOOSTER FOR ENERGY HARVESTING APPLICATIONS(ProquestNorth Carolina Agricultural and Technical State University, 2024) Hakami, Hadi Ahmad; Xie, Zhijian; Eroglu, AbdullahThis dissertation focuses on designing and developing a dual-band RF-DC rectifier and DC- DC booster, operating at 900 MHz and 2.4 GHz, for efficient energy harvesting applications. As the demand for sustainable energy sources grows, converting ambient radio frequency (RF) energy into usable direct current (DC) power offers a promising solution for powering low-power electronic devices such as wireless sensors and Internet of Things (IoT) devices. The proposed system aims to continuously harvest ambient RF energy, providing a reliable and sustainable energy source. The research begins with the design of a dual-band antenna capable of efficiently capturing RF signals at 900 MHz and 2.4 GHz. This antenna is integrated with an RF-DC rectifier circuit optimized for high conversion efficiency. The rectified DC voltage is then stepped up using a DC- DC booster circuit to ensure sufficient output voltage for various low-power devices. Component selection is critical, with diodes, capacitors, transformers, and transistors meticulously chosen based on their performance characteristics to maximize efficiency. Advanced simulation tools such as ADS (Advanced Design System) and HFSS (High-Frequency Structure Simulator) are employed to model and optimize the antenna, rectifier, and booster circuits, ensuring optimal performance under different operating conditions. Prototyping and testing validate theoretical designs. Circuits are fabricated on printed circuit boards (PCBs) and assembled for experimental evaluation. An experimental test bench measures the performance of the antenna, rectifier, and booster at various RF input power levels and frequencies. Key performance metrics, including conversion efficiency, output voltage, and power density, are assessed to determine the system's effectiveness. v Energy storage components, such as supercapacitors, are integrated to enhance the system's capability to provide continuous power. The integrated system's performance is evaluated by powering low-power devices, demonstrating its potential for real-time applications. Data analysis identifies performance bottlenecks, leading to iterative design optimizations to improve overall efficiency and reliability. The optimized rectifier and booster circuits are integrated into a complete RF energy harvesting (RFEH) system in the final phase. This system is tested in real-world scenarios, demonstrating its capability to power wireless sensors and IoT devices using ambient RF energy. The successful implementation underscores its potential to contribute to sustainable and renewable energy solutions, offering a reliable power source for an increasing number of low-power electronic devices. This comprehensive study, encompassing design, simulation, prototyping, testing, and optimization, presents a viable approach to harnessing ambient RF energy for practical applications. The results suggest that dual-band RF energy harvesting is a promising technology for sustainable energy management, providing continuous power to low-power devices and advancing self-sustaining electronic systems.23 0Item Restricted Low Cost Transparent and Flexible Antenna for Next Generation Communication Networks(University of Illinois at Chicago, 2024-02-09) Alsaab, Nabeel; Chen, Pai-YenNext-generation antenna design plays a vital role in enabling technologies in fifth generation (5G) and beyond fifth-generation (B5G) wireless networks. 5G and B5G technologies are envisioned to provide ubiquitous connectivity, enhanced coverage, ultra reliable low latency, and high data rates to meet societal and industrial needs. Furthermore, they are envisioned to unleash the potential of machine-to-machine communication and internet-of-things (IoTs) to build an ecosystem where networks can provide instantaneous connectivity for billions of connected devices. However, one challenge to the wide deployment of such a level of connectivity is that traditional antennas used in the current 4G and 4G-LTE systems are often large and intrusive. The exponential growth in demand for IoT devices, gateways and other wireless modulus, alongside with aesthetics requirement and cost considerations, have driven engineers to research “invisible” optically- transparent antennas and arrays that can be used in access points and signal repeaters embedded into existing urban infrastructure, without spoiling the aesthetic appearance of the environment and architectures. This thesis focuses on development of robust, cost-effective, and ecologically acceptable nanomaterials for optically transparent antennas, intelligent surfaces, and radio-frequency (RF) devices. Particularly, a large- area, ultralow-profile and mechanically-flexible transparent conductive films (TCFs) based on the metal-dielectric nanocomposite (MDNC) will be used to build these key component in next- generation communication systems. Moreover, the optimal design of MDNC, which exhibits high optical transparency and decently low electrical resistivity, will be conducted using the optical nanocircuit theorem and transfer matrix method. The versatility of the MDNC-TCF is demonstrated by implementing various transparent and flexible antennas, in the form of omnidirectional linear dipole, unidirectional Yagi-Uda antenna, microstrip patch antenna, and novel solar-powered body-wearable antenna. This research also studies transparent metasurfaces and their applications in antenna radomes, which can be used in, for example, high-gain and low- RCS Fabry-Perot cavity antennas and solar-powered base station antenna. The results of this thesis will pave the way for the practical realization of low-cost, conformal and optically- transparent antennas and intelligent surfaces that are capable of enhancing and optimizing connectivity of 5G and B5G communication systems.22 0