Millimetre wave devices for high frequency mobile, space and IoT applications

In this thesis, Hollow Substrate Integrated Waveguides (HSIW) for microwave and millimetre-wave applications are thoroughly analyzed and investigated. New millimetre wave device fabrication techniques, a new HSIW transmission line, and a curved HSIW structure are all presented. The three published journals that form the basis of the thesis, make major contributions to the field of HSIW technology. An innovative technique for constructing HSIWs using a cheap, readily available material and a streamlined production process is covered in the first journal paper. The article outlines a step-by-step fabrication process and assesses the HSIW structures’ performance in terms of bandwidth, insertion loss, and return loss. Later on, the new HSIW structure is analyzed and it shown that, it offers considerable benefits over standard HSIWs in terms of performance characteristics, including propagation loss and bandwidth. It is based on the manufacturing approach discussed previously. The thesis presents the novel HSIW structure’s design, manufacturing, performance assessment and a comparison to other existing HSIWs. After the straight sections presentation, the design, production and performance assessment of a novel curved HSIW structure are analyzed. This structure has a number of possible uses in microwave and millimetre-wave systems. In terms of performance characteristics, the thesis contrasts the curved HSIW structure’s performance with that of previously designed straight section HSIW structures. The thesis in overall, provides a comprehensive review of the fundamental concepts and design principles of HSIWs, including their electromagnetic characteristics, propagation modes, and transmission properties. The research presented in this thesis can contribute to the development of advanced HSIW-based devices and systems for high-frequency communication and other emerging applications. In conclusion, this thesis presents significant contributions to the field of HSIW technology, drawing on three previously published journal articles and a comprehensive investigation of HSIWs’ fundamental concepts, design principles, and potential applications.