Engineering Commons^™

Low Cost Scanning Arrays, Matilda Gabriela Livadaru

FIU Electronic Theses and Dissertations

Over the past decades, phased arrays have played a significant role in the development of modern radar and communication systems. The availability of printed circuit technology and ease of integration with microwave components, as well as the development of low profile and low weight approaches, have also played an important role in their conformal adaptation. However, fabrication costs remain prohibitive for many emergent platforms, including 5G base stations and autonomous vehicles, when compared to a conventional mechanically steered passive array. Therefore, cost reductions in the fabrication and integration of modern phased arrays are essential to their adaptation for many upcoming …

Reconfigurable Antennas Using Liquid Crystalline Elastomers, John Gibson

FIU Electronic Theses and Dissertations

This dissertation demonstrates the design of reversibly self-morphing novel liquid crystalline elastomer (LCE) antennas that can dynamically change electromagnetic performance in response to temperature. This change in performance can be achieved by programming the shape change of stimuli-responsive (i.e., temperature-responsive) LCEs, and using these materials as substrates for reconfigurable antennas. Existing reconfigurable antennas rely on external circuitry such as Micro-Electro-Mechanical-Systems (MEMS) switches, pin diodes, and shape memory alloys (SMAs) to reconfigure their performance. Antennas using MEMS or diodes exhibit low efficiency due to the losses from these components. Also, antennas based on SMAs can change their performance only once as …

Origami Antennas For Novel Reconfigurable Communication Systems, Xueli Liu

FIU Electronic Theses and Dissertations

Antennas play a crucial role in communication systems since they are the transmitting/receiving elements that transition information from guided transmission to open-space propagation. Antennas are used in many different applications such as aerospace communications, mobile phones, TVs and radios. Since the dimensions of antennas are usually physically proportional to the wavelength at their operating frequencies, it is important to develop large antennas and arrays that can be stowed compactly and easily deployed. Also, it is important to minimize the number of antennas on a platform by developing multifunctional antennas.

The first aim of this research is to develop new deployable, …

Novel Strongly Coupled Magnetic Resonant Systems, Daerhan Liu

FIU Electronic Theses and Dissertations

Wireless power transfer (WPT) technologies have become important for our everyday life. The most commonly used near-field WPT method is inductive coupling, which suffers from low efficiency and small range. The Strongly Coupled Magnetic Resonance (SCMR) method was developed recently, and it can be used to wirelessly transfer power with higher efficiency over a longer distance than the inductive coupling method.

This dissertation develops new SCMR systems that have better performance compared to standard SCMR systems. Specifically, two new 3-D SCMR systems are designed to improve the angular misalignment sensitivity of WPT systems. Their power transfer efficiency for different angular …

Plasmonic Nanoplatforms For Biochemical Sensing And Medical Applications, Arash Ahmadivand

FIU Electronic Theses and Dissertations

Plasmonics, the science of the excitation of surface plasmon polaritons (SPP) at the metal-dielectric interface under intense beam radiation, has been studied for its immense potential for developing numerous nanophotonic devices, optical circuits and lab-on-a-chip devices. The key feature, which makes the plasmonic structures promising is the ability to support strong resonances with different behaviors and tunable localized hotspots, excitable in a wide spectral range. Therefore, the fundamental understanding of light-matter interactions at subwavelength nanostructures and use of this understanding to tailor plasmonic nanostructures with the ability to sustain high-quality tunable resonant modes are essential toward the realization of highly …

Anomalous Properties Of Sub-10-Nm Magnetic Tunneling Junctions, Mark Stone

FIU Electronic Theses and Dissertations

Magnetic Logic Devices have the advantage of non-volatility, radiation hardness, scalability down to the sub-10nm range, and three-dimensional (3D) integration capability. Despite these advantages, magnetic applications for information processing remain limited. The main stumbling block is the high energy required to switch information states in spin-based devices. Recently, the spin transfer torque (STT) effect has been introduced as a promising solution. STT based magnetic tunneling junctions (MTJs), use a spin polarized electric current to switch magnetic states. They are theorized to bring the switching energy down substantially. However, the switching current density remains in the order of 1 MA/cm2 in …