Abstract of doctoral thesis Misailidis Ilias

The Doctoral Dissertation on the subject: "Design of MIMO antennas to deal with blackouts at 5G millimetre frequencies", covers a wider scientific field of great interest, both telecommunications and commercial. The telecommunications coverage with Next Generation Cellular Networks (NxGnCNet) will bring new speeds, perspectives, and possibilities to telecommunications infrastructures. This makes it necessary not only to study these infrastructures but also how these infrastructures can make the most of a complex technology like 5G.

My research activity at the first level will comprehensively cover the already existing technologies at the level of knowledge. It will be studied, primarily if these technologies fall behind in meeting the needs of 5G technology and secondarily if they fall behind, more precisely. In this first stage, results should be produced, either of the need for change in already existing technologies or of the magnitude of changes that will need to be made so that existing infrastructures can provide the greatest possible effect on 5G technology. The already implemented technologies that will be studied are 3G and, of course, 4G, and of course, phenomena such as Wireless Propagation Phenomena, Propagation Mechanisms, Reflection / Refraction Transmission, Single Reflection (air-ground), Diffraction Losses, Fresnel Zones, Ground Wave Propagation, Sky Wave Propagation, LoS Space, Line-of-Sight, Multipath Propagation, Coherence Bandwidth, MIMO systems, Fading Channels, Doppler Spread, Coherence Time, Smart Antennas.

In the second stage, there will be extensive research activity on Next Generation Cellular Networks (NxGnCNet) technologies focusing on the characteristics of 5G technology. There will be a study of its potential, but also an expansion study, technologically and qualitatively, either for more significant or better utilization of it. My Research activity in this phase will focus on the analysis of the directional lobes of MIMO antennas with the primary objective of Link Budget and Channel Estimation. The techniques will focus on how the pod following the user in 360 degrees will remain unaffected by other properties, how much it will have, and how its width can also remain unaffected by these changes. Then, these results, after being measured and evaluated, will be used for the construction of MIMO antennas. At this stage, microwave and telecommunication devices and capabilities simulation programs such as ANSYS 17 and scientific programs such as Matlab Simulink will be used. A broad and analytical effort will be made to analyze and study the phenomena mentioned for their behaviour in 5G technologies. Thus, we will have a benchmark for how well the transition to next-generation communications (NxGnCNet), such as 5G, can be adequately and reliably covered. In addition, in my main research project, the energy efficiency of this technology, which is a very important part of modern telecommunication networks, will be studied.

In the third stage, having the knowledge of the leading research program from all the previous stages, an approach will be made for the application of this technology (5G) in defence systems where we encounter the phenomenon of their coexistence together with other devices in the microwave range, high frequencies and high voltages, and we will see how its behaviour could be affected in such an environment. With this background, significant results can be produced for the technologies of the next generations.