الفهرس 
Chapter 1 : IntroductionOnly 14 pages are availabe for public view
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Abstract
Nowadays, as a result of the rabid growth of fast wireless communication systems, wide operating frequency bands and, high-gain Tx / Rx antennas become an urgent demand. Such systems are intended to attain high-speed and high data rate transfer with much wider bandwidth. So, millimeter-wave (MMW) frequency bands can be considered a good candidate for such system realization. However, the MMW frequency bands suffer from severely high attenuation due to the wave absorption by oxygen molecules in the propagation atmosphere. In order to overcome this problem, high-gain directive antennas are needed. They have been utilized in various mobile communication applications like base station antennas or broadband phased array antennas. In this thesis, a wideband 5G MIMO CXRL LPDA antenna with ENZ index metamaterial is presented. The proposed design achieves very wideband performance extending from 26 to more than 39 GHz. The antenna achieved a realized gain of 9.59 dBi at 28 GHz and 11.1 dBi at 36 GHz. The proposed antenna shows stable radiation characteristics over the operating bandwidth, which makes it a proper candidate for various 5G applications. Quad element MIMO array is built using CXRL LPDA elements. The array shows superior performance in terms of Gain, port isolation, ECC, DG, and CCL. In addition, a wideband 5G monopole antenna with three loaded stubs is presented. The proposed design achieves very wideband performance extending from 20 to 40 GHz. The antenna achieved a gain of 4.3238 dBi at 28 GHz and 5.078 dBi at 38 GHz. The proposed antenna shows stable radiation characteristics over the operating bandwidth, which make it a proper candidate for various 5G applications. Significant research work has focused on enhancing the gain of microstrip patch antennas. To enhance the overall antenna gain, different gain-enhancing techniques have been investigated. A circularly polarized (CP) high gain hybrid rectangular patch/horn antenna with chamfered corners is designed. The proposed design antenna has an operating band from 26.7 to 28.7 GHz. The circular polarization is achieved, and the overall gain is about 10.9 dBi at 28 GHz. The design and implementation of a beam-steering antenna array using a 4x4 Butler matrix feed network (BMN) for 5G applications is presented. The proposed antenna array can achieve a gain of 14 dBi and a steering range of (+16 º, -47 º, +46.5 º, -15.7 º) to cover an angular range extending from 45º to 135º. To achieve that, a simple, 4x4 Butler matrix etched on a single-layer microstrip structure is designed, optimized, and fabricated.