Design and optimization of microwave antenna array for next-generation wireless networks

This Ph.D. thesis presents different novel high-performance antenna systems for satellite communication, 5G wireless networks, and RADAR system applications. The research deals with several aspects of antenna during design to produce electromagnetic structures for exhibiting high gain, wide bandwidth, and cost-effective fabrication. To meet the demands of modern communication systems, all critical issues present in conventional antennas are addressed and solved through proper electromagnetic design. The first part of this thesis focuses on planar transmitarray antenna, which provides dual polarized radiation while maintaining a compact architecture. After fabrication and characterization, this multi-layer phase-compensating structure demonstrates a peak gain of approximately 21 dB with beam steering up to ±30°. This transmitarray can be considered as a practical alternative to the conventional high gain antenna as it features low transmission loss, accurate phase control, and low side-lobe levels. Next, the thesis focuses on additive manufacturing techniques based Fabry–Pérot cavity antennas. In this antenna, gain is enhanced through constructive interference executed by partially reflective surfaces, while low-cost and scalable fabrication is enabled through conductive inkjet printing. Cost-effective manufacturing method is used to produce flexible microwave structure. Measurement shows that this fabricated cavity antenna exhibits a maximum gain of approximately 13.2 dBi with a 3 dB gain bandwidth of 24.5% proves its potential. Wideband magneto-electric dipole antennas integrated with advanced electromagnetic structures are addressed by the subsequent work. Wide impedance bandwidth with reduced side-lobe levels is exhibited by the electromagnetic bandgap structure-based magneto-electric dipole antenna at millimeter wave frequency, while enhanced gain with slant polarization-based radiation is provided by metasurface (artificial magnetic conductor) based dipole antenna for 5G applications. The performance evaluation of these designs illustrated that the effective use of EBG (Electromagnetic Bandgap) and AMC (Artificial Magnetic Conductor) structures can control unwanted surface mode propagation for shaping radiation pattern and reduce the overall profile thickness respectively. Moreover, stable and symmetric radiation pattern is observed over the targeted band for the internal characteristics of the magneto electric dipole antenna. Finally, a wideband patch antenna array for SOTM (Satellite Communications on the Move) applications is demonstrated which provide wide impedance bandwidth, high gain, and stable radiation patterns. This design addresses the challenges of wideband operation required for mobile satellite communications and highlight the capability of polarization control with easy integration of external electronic circuitry. Furthermore, investigation on different fabrication and system set up tolerances show minimal effect on performance makes this array more attractive. Altogether, a comprehensive framework for designing, fabricating, and deploying antenna system of high-performance in terms of bandwidth, gain, radiation pattern, and profile compactness is established by this thesis which is significant for next-generation wireless communication technologies.