الفهرس 
CHAPTER 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
The Internet of Things (IoT) technology has attracted significant attention in recent years due to its pledge of making life easier for humans. IoT covers enormous applications and each application’s environment is unique. As flexible antennas are crucial in various IoT applications, therefore, the objective geometry of the antenna in this Ph.D. thesis is a flexible antenna that conforms to any surface. Flexible antennas, on one hand, have shown to be successful in satisfying non-electromagnetic needs. On the other hand, the antenna’s reconfigurability makes it possible to have a customizable electromagnetic performance. In other words, by simply controlling the antenna’s current flow, a single-element antenna or an antenna array can function as a multiple-element or multiple-arrays, respectively. A typical reconfigurable antenna can alter its radiation pattern, resonance frequency, polarization, and other performance parameters. The various types of reconfigurability on flexible antennas for diverse applications in an IoT environment are comprehensively proposed in this Ph.D. dissertation.
The first type of reconfigurability discussed is the “radiation pattern reconfigurability”, where the reconfigurability is applied to a flexible meandered Inverted-F antenna in a wireless capsule endoscopy system (first contribution). Regardless of orientation or location inside the gastrointestinal tract, the proposed capsule antenna provides reconfigurable omnidirectional radiation pattern. Two PIN diodes that produce four states are used to create the reconfigurable omnidirectional radiation pattern. With the assist of a microcontroller inside the capsule, it is possible to simultaneously choose which state provides the most gain. The proposed capsule antenna operates at 433 MHz, with a volume of 30 × 15 × 0.254 mm3 in the flat form and fits inside a capsule with a length of 26 mm and a diameter of 12 mm in the conformal form. It is simulated in different orientations in muscle, stomach, and colon homogenous boxes. Moreover, it achieves a realized gain of -33.64 dBi inside a 100 mm colon cube. After that, the proposed antenna is then examined inside a voxel model. Furthermore, the robustness of the communication system that includes the capsule antenna is verified. The maximum input power (11 mW) is determined from the Specific Absorption Rate (SAR) in the colon. The link Carrier-to-Noise ratio (C/No) is greater than the required C/No for a 4 Mbps data rate and distances up to 3 meters. The proposed capsule antenna’s performance is validated by fabricating and measuring it inside a muscle phantom.
The second type of reconfigurability discussed in this dissertation is “Frequency reconfigurability”, where the reconfigurability is applied to a flexible slotted hexagon-like antenna for on-body multiple applications (second contribution). It attains a size of 45 × 65 mm2. The proposed antenna is hexagonal in shape and has a single ON/OFF PIN-diode short to the ground. When the switch is turned ON, it operates at 433 MHz and operates at 915 MHz when the switch is OFF. It functions as an on-body receiver for the Wireless Capsule Endoscopy system at 433 MHz and as a receiver for an implanted arm antenna at 915 MHz. It is simulated on a cylindrical substance with the average dielectric constant of skin, fats, and muscle. The proposed antenna is fabricated and examined in a liquid that resembles average biological material and on the human arm as well. The fabricated reconfigurable antenna provides good matching at both 446 MHz and 934 MHz on a cylindrical container. At the OFF state, it is matched well on the human arm. Furthermore, at the ON-state, the fabricated on-body antenna is tested as a receiver for the capsule antenna.
The third type of reconfigurability discussed is the “polarization reconfigurability”, where the reconfigurability is applied to the proposed aperture-coupled antenna array with hourglass aperture for off-body application (third contribution). The array consists of two elements, occupies an area of 200 × 100 mm2 and operates at 915 MHz. The off-body array switches between linear polarization, left-hand circular polarization and right-hand circular polarization. The array is fed by a 2-way in-phase power divider which is firstly designed and fabricated as a stand-alone power divider (fourth contribution), then it is adjusted to be integrated with the array. Moreover, the proposed array is studied as an off-body receiver for a transmitting in-body capsule antenna implemented at 915 MHz.