الفهرس 
Thesis Contribution
ANTENNA DESIGN FOR MICROWAVE RANGEOnly 14 pages are availabe for public view
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Abstract
of this work is a printed multiple-input multiple-output (MIMO) antenna for the fifth-generation millimeter-wave applications, with advantages such as compact size, good MIMO diversity performance, and simple geometry. It offers Ultra-Wide Band (UWB) operation from 25 to 50 GHz using a Defected Ground Structure (DGS) technology. The antenna’s compact size (33 mm × 33 mm × 0.233 mm) The fifth generation of wireless communication technology has revolutionized the way we use the internet and interact with the world around us. It offers users high-speed data, improved capacity, and reliable communication applications. The key to fifth-generation technology is the use of millimeter wave frequency bands, which provide the necessary bandwidth. Crucial elements of this technology are the antenna and millimeter wave components, which can greatly enhance data delivery speed and capacity. This cutting-edge technology has enabled us to reach a new level of performance, allowing us to transmit and access data faster and more reliably than ever before. With these components, future generations will be able to take advantage of the latest technologies in a way that was impossible for previous generations.
The first contribution makes it suitable for integrating different telecommunication devices for various applications. Additionally, its orthogonal positioning of individual elements increases their isolation, providing the best diversity performance. Its performance was investigated in terms of S-parameters and MIMO diversity parameters, and verified by measurements, exhibiting a good match between simulated and measured results. The antenna achieves UWB, high isolation, low mutual coupling, and good MIMO diversity performance, making it a good candidate for 5G mm-Wave applications.
The second contribution of this thesis is to design compact UWB couplers based on Substrate Integrated Gap Waveguide (SIGW) technology that covers the KU-band and mm-Wave band. These couplers are key components in signal processing for wireless communication, providing a way to control the power distribution of the signal across different ports. They can be used to achieve beamforming and adaptive antenna systems. The first proposed coupler is a novel circular reconfigurable metasurface (MS)-based compact ultra-wideband (UWB) hybrid coupler, and the second one is a 3dB compact UWB SIGW based hybrid coupler.
The first proposed coupler is developed for Ku-band applications. The coupler is developed using SIGW technology. The coupler structure consists of two layers: the bottom layer, with periodic structures and ridges that guide the wave in the required direction with minimum dispersion, and the top layer, which is a circular dielectric gap loaded with a solid top ground for a non-reconfigurable coupler. This layer contains an artificial metasurface of Jerusalem cross elements with copper etched around the edges for a reconfigurable coupler. This MS surface can be mechanically rotated to offset the magnitude and phase of the signal going to the through and coupled ports. Simulations show that the reconfiguration can be accomplished by rotating the MS around the source coupler’s central axis from 0° to 180° in the counterclockwise direction. The operating frequency range of the coupler is between 11.94 and 16.91 GHz, covering the whole Ku-band. The coupler delivers continuously adjustable attenuation and isolation.
The second coupler is developed for 5G mm-Wave applications. The design process started with the implementation of a unit cell of the gap waveguide structure that satisfied the required bandwidth of the coupler. A supercell was then created. A network of full ridges was constructed. A further step was to design a coupling section that achieved the required power distribution along the coupling and isolated ports. This coupling section was implemented using a novel approach of inserting an elliptical slot with a variable major and minor axis and a certain orientation that achieved the standard performance of a 3 dB directional coupler with 90° ± 9% phase shift. To precisely adjust the amplitude and phase, additional vias were added perpendicular to the major axis of the slot, the dimensions and location of which had to be optimized. The Finite-Difference Time-Domain (FDTD) analysis method (CST Microwave studio) was adopted. Additionally, another novel approach was developed for this coupler such that the transition and gap layers were implemented on the same printed circuit board (PCB) layer, resulting in only two layers, compared to the usual three layers used in literature. The proposed coupler was fabricated and tested, and the results showed that it served the majority of frequency bands employed in 5G systems in the USA and Canada.
The last contribution in this thesis is an antenna that provides a high gain and efficient performance for X-band applications. The antenna consists of three layers of substrate material with an overall dimension of 44 × 41 × 1.6 mm³. The design features a flag- and eagle-shaped structure with two multilayer substrates of ε_r= 4.4. Simulation analysis using the CST Studio Suite Electromagnetics (EM) solver and experimental validation using the ROHDE & SCHWARZ ZVB20 network analyzer show good agreement between the two. The antenna operates at two frequencies within the X band range: 7.15 GHz (from 7 GHz to 7.3 GHz) and 8.61 GHz (from 8.4 GHz to 8.75 GHz), with 5.68/6.45 dB gain and 86%/89% radiation efficiency. This new design presents an innovative and artistic approach to multi-band antenna design, using multilayer substrates and DGS technology.
The MIMO antenna, mm-Wave, and microwave components introduced in this thesis positively contribute to mm-Wave and KU-band applications. Their implementation is expected to enhance the performance of 5G wireless communication systems.