Design and analysis of CPW-fed compact planar antennas for ultra wideband communication systems

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] In this research, three new designs of planar compact ultra-wideband (UWB) antennas have been studied, simulated, and experimentally measured. Their structures are not complicated in design, easy in fabrication with low cost. They are in different physical sizes and considered small compared to many recent published UWB antennas that have similar performance. The proposed antennas have ultra-wide bandwidth that cover the entire bandwidth allocated by FCC for such applications. They are made to be planar structure with a single layer in order to be easier in fabrication and for use in wireless devices and applications. The used feeding technique is coplanar wave-guide (CPW) in all of them due to the great advantages of this feeding methodology. Each design has certain more superiority over the others either in terms of operating frequency range, power gain, radiation pattern, or structure size. Although, all compact patch antennas demonstrate high performance results and are very suitable for ultra-wideband systems. Finally, since there are a variety of ultra-wideband applications with several characteristics requirements, the research is composed of three different sizes of compact planar single layers antennas. These antennas have similar or better performance than some other large size designs, which makes it suitable for very compact wireless gadgets. Thus, the ultra-wideband (UWB) systems designer will be able to select the most appropriate design for the application based on the antenna characterizes and size

Design, simulation, and analysis of reconfigurable antennas in gigahertz regime.

May 2013."A Thesis presented to The Faculty of the Graduate School at the University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science."Thesis supervisor: Dr. Naz E. Islam.Includes bibliographical references (pages 79-85).The entire text is included in the research.pdf file; the abstract appears in the short.pdf file; a non-technical general description appears in the public.pdf file.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] This research focuses on the design and analysis of a reconfigurable antenna where the radiation pattern and its characteristics are altered in each operating state. Specifically three versions of the reconfigurable antenna have been designed, all made from the same materials. An industry standard simulation code is used for simulation and analysis. It is expected that each antenna design can be used for specific applications. The first antenna design is optimized for radiation. It has the same resonant frequency in each switching state, an S11 value of -50 dB, and a difference in the angle of more than 90 between each state. The second design is a modified version of the first antenna, and has very high directivity and gain values and with the highest angle between the radiation patterns between the states. The resonant frequency of the third reconfigurable structure is less than the previous two designs but it has a wider bandwidth. The antenna designs have applications in saving battery power, avoiding detectability and as a wide band radiation pattern reconfigurable antenna respectively

Compact Design of 2 × 2 MIMO Antenna with Super-Wide Bandwidth for Millimeters Wavelength Systems

A novel compact planar 2 × 2 antenna system with super-wide bandwidth is presented in this paper. The MIMO antenna has four square-shaped patches with two slots in each that are interconnected with each other using four strip lines printed on a substrate of Rogers Duroid RT 5880 with relative permittivity of εr = 2.2 and tangent loss of δ = 0.0009. The proposed antenna system has a partial ground plane with two enhancement fractured slots. The design is characterized by a super-wide impedance starting from 15.2 to 62 GHz (a bandwidth of 46.8 GHz) and compact total system size of 11.2 × 15.25 mm2 with a thickness of 0.12 mm. The proposed MIMO design has omnidirectional radiation pattern for far field and the achieved peak gain reaches 13.5 dBi. The presented planar antenna which relies on computer aided design, has been designed and simulated using an industrial standard simulation code. Its performance results showed that the MIMO design is characterized by super wide bandwidth, omnidirectional radiation pattern, and high-power gain with miniaturized physical size; thus, it is suitable for radio-frequency identification (RFID) systems, fifth-generation applications, ultra-wideband systems, and others

Compact Design of 2 × 2 MIMO Antenna with Super-Wide Bandwidth for Millimeters Wavelength Systems

A novel compact planar 2 × 2 antenna system with super-wide bandwidth is presented in this paper. The MIMO antenna has four square-shaped patches with two slots in each that are interconnected with each other using four strip lines printed on a substrate of Rogers Duroid RT 5880 with relative permittivity of εr = 2.2 and tangent loss of δ = 0.0009. The proposed antenna system has a partial ground plane with two enhancement fractured slots. The design is characterized by a super-wide impedance starting from 15.2 to 62 GHz (a bandwidth of 46.8 GHz) and compact total system size of 11.2 × 15.25 mm2 with a thickness of 0.12 mm. The proposed MIMO design has omnidirectional radiation pattern for far field and the achieved peak gain reaches 13.5 dBi. The presented planar antenna which relies on computer aided design, has been designed and simulated using an industrial standard simulation code. Its performance results showed that the MIMO design is characterized by super wide bandwidth, omnidirectional radiation pattern, and high-power gain with miniaturized physical size; thus, it is suitable for radio-frequency identification (RFID) systems, fifth-generation applications, ultra-wideband systems, and others

A multi-stage SEIR model to predict the potential of a new COVID-19 wave in KSA after lifting all travel restrictions

The complete lifting of travel restrictions to KSA takes place after 3rd of January 2021. There are fears that KSA will confront a new COVID-19 wave, especially when the most of countries that resumed the international flights are suffering now from the second surge. Fortunately, more than one Covid-19 Vaccine have been rolled out. However, herd immunity could be reached only through widespread vaccination. COVID-19 vaccines need more time to be properly protective, especially in front of people refusing to get vaccinated. A modified multi-stage SEIR model, with distinct reproductive numbers corresponding to before and after lockdown is employed to predict the potential of a new pandemic wave. First, the two-stage model employed to find the best fitting for the reproductive numbers. Then, the model is extended to three-stage one to investigate the relaxation. However, the modified model detects a second wave in early stage from 28th May to 17th June 2020 before even succeeding controlling the first outbreak. Subsequently, the four-stage SEIR model is used to predict the end of the second wave. Moreover, the model is employed to test the potential of a new pandemic surge after the international flights are resumed

H∞ Reliable Dynamic Output-Feedback Controller Design for Discrete-Time Singular Systems with Sensor Saturation

In this study, we investigate the H∞ fault-tolerant control problem for a discrete-time singular system which is subject to external disturbances, actuator faults, and sensor saturation. By assuming that the state variable of the system is unavailable for measurement, and the actuator fault can be described by a Markovian jump process, attention is mainly focused on designing a reliable dynamic output-feedback (DOF) controller able to compensate for the effects of the aforementioned factors on the system stability and performance. Based on the sector non-linear approach to handle the sensor saturation, a new criterion is established to ensure that the closed-loop system is stochastically admissible with a γ level of the H∞ disturbance rejection performance. The main aim of this work is to develop a procedure for synthesizing the controller gains without any model transformation or decomposition of the output matrix. Therefore, by introducing a slack variable, the H∞ admissibility criterion is successfully transformed in terms of strict linear matrix inequalities (LMIs). Three practical examples are exploited to test the feasibility and effectiveness of the proposed approach

Implementing a Symmetric Lightweight Cryptosystem in Highly Constrained IoT Devices by Using a Chaotic S-Box

In the Internet of Things (IoT), a lot of constrained devices are interconnected. The data collected from those devices can be the target of cyberattacks. In this paper, a lightweight cryptosystem that can be efficiently implemented in highly constrained IOT devices is proposed. The algorithm is mainly based on Advanced Encryption Standard (AES) and a new chaotic S-box. Since its adoption by the IEEE 802.15.4 protocol, AES in embedded platforms have been increasingly used. The main cryptographic properties of the generated S-box have been validated. The randomness of the generated S-box has been confirmed by the NIST tests. Experimental results and security analysis demonstrated that the cryptosystem can, on the one hand, reach good encryption results and respects the limitation of the sensor’s resources, on the other hand. So the proposed solution could be reliably applied in image encryption and secure communication between networked smart objects

Optimized Omnidirectional High-Reflectance Using Octonacci Photonic Crystal for Thermographic Sensing Applications

The transmittance of waves through one-dimensional periodic and Octonacci photonic structures was studied using the theoretical transfer matrix method for both wave-polarization-modes. The first structures were made up of the SiO2 and TiO2 materials. The objective here was to obtain a broad omnidirectional high reflector covering the infrared spectrum of a thermographic camera [1–14 µm] and, especially, to prevent the transmission of emitted human body peak radiation λmax = 9.341 µm. By comparing the periodic and Octonacci structures, we found that the last structure presented a main and wide photonic band gap near this human radiation. For that, we kept only the Octonacci structure for the rest of the study. The first structure did not give the aspired objective; thus, we replaced the TiO2 layers with yttrium barium copper oxide material, and a significant enhancement of the omnidirectional photonic band gap was found for both TE and TM polarization modes. It was shown that the width of this band was sensitive to the Octonacci iteration number and the optical thickness (by changing the reference wavelength), but it was not affected by the ambient temperature. The number of layers and the thickness of the structure was optimized while improving the omnidirectional high reflector properties

Power System Reconfiguration in Distribution Network for Improving Reliability Using Genetic Algorithm and Particle Swarm Optimization

This paper presents an optimal method for optimizing network reconfiguration problems in a power distribution system in order to enhance reliability and reduce power losses. Network reconfiguration can be viewed as an optimization problem involving a set of criteria that must be reduced when adhering to various constraints. The energy not supplied (ENS) during permanent network faults and active power losses are the objective functions that are optimized in this study during the reconfiguration phase. These objectives are expressed mathematically and will be integrated into various optimization algorithms used throughout the study. To begin, a mathematical formulation of the objectives to be optimized, as well as all the constraints that must be met, is proposed. Then, to solve this difficult combinatorial problem, we use the exhaustive approach, genetic algorithm (GA), and particle swarm optimization (PSO) on an IEEE 33-bus electrical distribution network. Finally, a performance evaluation of the proposed approaches is developed. The results show that optimizing the distribution network topology using the PSO approach contributed significantly to improving the reliability, node voltage, line currents, and calculation time

Implementing a Symmetric Lightweight Cryptosystem in Highly Constrained IoT Devices by Using a Chaotic S-Box

In the Internet of Things (IoT), a lot of constrained devices are interconnected. The data collected from those devices can be the target of cyberattacks. In this paper, a lightweight cryptosystem that can be efficiently implemented in highly constrained IOT devices is proposed. The algorithm is mainly based on Advanced Encryption Standard (AES) and a new chaotic S-box. Since its adoption by the IEEE 802.15.4 protocol, AES in embedded platforms have been increasingly used. The main cryptographic properties of the generated S-box have been validated. The randomness of the generated S-box has been confirmed by the NIST tests. Experimental results and security analysis demonstrated that the cryptosystem can, on the one hand, reach good encryption results and respects the limitation of the sensor’s resources, on the other hand. So the proposed solution could be reliably applied in image encryption and secure communication between networked smart objects