On 22 August 2025 at 12:00, Jaanus Kalde will defend his doctoral thesis in Physical Engineering
“Extending frequency and steering range of amplifier-antenna array via controlled mutual coupling”
Jaanus Kalde is pursuing his doctoral studies under a cotutelle agreement between the University of Tartu and Aalto University. Accordingly, his doctoral defence will take place at Aalto University.
Time and venue of the defence:
22 August 2025, at 12:00
TU2, Maarintie 8, Espoo, Finland
Supervisors:
Professor Alvo Aabloo, University of Tartu
Professor Ville Viikari, Aalto University
Opponent:
Professor Cyrille Menudier, University of Limoges (France)
Summary:
Radio waves are an integral part of our daily lives, from mobile phones to radar systems. At the heart of these devices are antennas, and often, multiple antennas are used together, forming what are known as array antennas. When these antennas are placed close to each other, they inevitably start to influence one another – a phenomenon called 'coupling.' Traditionally, efforts are made to minimise this interaction, as it can degrade system performance and make it less efficient. As antennas become smaller and more complex, getting rid of coupling becomes increasingly difficult.
My doctoral research, however, explored a different question: could this often-unwanted coupling actually be turned into an advantage? To investigate this, I didn't look at antennas in isolation. Instead, I considered the entire radio system as a whole – the antennas, the electronics that feed them, and the signals themselves. The core idea was to cleverly manage and modify the outgoing signals in such a way that the mutual interaction between antennas helps improve performance, rather than hindering it.
And it worked! We demonstrated that such a holistic approach and the deliberate use of coupling can expand the system's frequency range and improve how widely the signal can be steered. This means that by understanding and harnessing the 'cooperation' between antennas, instead of avoiding it at all costs, we can build more efficient and capable communication and radar systems for the future.
