Design synthesis and miniaturization of multiband and reconfigurable microstrip antenna for future wireless applications

Tese de Doutoramento. Engenharia Electrónica e de Computadores - Telecomunicações. Faculdade de Engenharia. Universidade do Porto. 201

An Overview of Dye Wastewater and Its Treatment via Coagulation-Flocculation with Iron Chloride

The chapter discusses an overview of the removal of colour, COD, turbidity and TSS from dye wastewater using iron chloride as a coagulant in coagulation-flocculation process. This chapter explained dye wastewater definition and characteristics, dye wastewater treatment methods and factors that influence the coagulation-flocculation processes of dye wastewater treatment. The chapter also gives an explanation about various chemical coagulant used in dye wastewater treatment process and the efficiency of these coagulants

Multireflector Antennas - Cascaded Structures with Frequency Selective Surfaces

The problem of increasing the gain of directional multiband antennas is solved in the paper. A single-fed multiband (wideband) planar dipole is combined with cascaded (sandwiched) reflectors made of frequency selective surfaces. Each of those reflectors is placed in a quarter-wavelength distance from the dipole at the frequency of operation. The impedance matching is particularly achieved by active element properties, and impedance symmetrization. Further transformation is made by a planar circuit, placed on the active element plane. The antenna gain is set by the reflector elements amount (reflector plane dimensions). The antenna structure enables its setting into arrays with in-phase feeding

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Analysis and Life Cycle Assessment of Printed Antennas for Sustainable Wireless Systems

Siirretty Doriast

Stretching the limits of dynamic range, shielding effectiveness, and multiband frequency response

In this dissertation, an RF MEMS variable capacitor suitable for applications requiring ultrawide capacitive tuning ranges is reported. The device uses an electrostatically tunable liquid dielectric interface to continuously vary the capacitance without the use of any moving parts. As compared to existing MEMS varactors in literature, this device has an extremely simple design that can be implemented using simple fabrication methods that do not necessitate the use of clean room equipment. In addition, this varactor is particularly suited for incorporating a wide range of liquid dielectric materials for specific tuning ratio requirements. Additionally, the shielding effectiveness performance of graphene-doped ABS thin films is investigated. The use of graphene as a replacement for metal fillers in composite EMI shielding materials is quickly becoming a widely-investigated field in the electromagnetic compatibility community. By replacing conventional metal-based shielding methods with graphene-doped polymers, low-weight, field-use temporary shielding enclosures can be implemented that do not suffer from mechanical unreliability and corrosion/oxidation like a traditional metal enclosure. While the performance of composite EMI shielding materials has not yet surpassed metals, the advantages of polymer-based shielding methods could find usage in a variety of applications. Finally, mutliband pre-fractal antennas fabricated via 3D printing are reported. These devices are the first to incorporate the advantages of 3D printing (rapid prototyping, fabrication of complex geometries otherwise unobtainable) with the advantages of self-similar antennas (increased gain and multiband performance) in a single device. The Sierpinski tetrahedron-based antenna design was both computationally modeled and physically realized to illustrate its potential as a solution to enable true multiband communication platforms

Performance and Improvement of Various Antennas in Modern Wireless Communication System

Today, the importance of wireless communication is known around the world. To achieve better communication, many techniques and methods have been introduced. Among these techniques, intelligent / adaptive antennas are a hot topic in the field of research. Smart antennas consist of several antenna arrays and are able to optimize the radiation and reception of dynamically desired signals. In order to avoid or mitigate interference, smart antennas may also introduce zero values towards the receivers by adaptively updating the weights associated with each antenna element. Smart antennas can also improve reception quality and reduce missed calls. The various existing surveys are also discussed to identify the research deficit for the scope of future research