Public defence in Radio Science and Engineering, M.Sc. Jaanus Kalde

The title of the thesis: Extending frequency and steering range of amplifier-antenna array via controlled mutual coupling

Thesis defender: Jaanus Kalde
Opponent: Professor Cyrille Menudier, University of Limoges, France 
Custos: Prof. Ville Viikari, Aalto University School of Electrical Engineering

Doctoral thesis, "Extending Frequency and Steering Range of Amplifier-Antenna Array via Controlled Mutual Coupling," proposes a new approach to designing the core technology behind wireless communication, such as the systems used for 5G, 6G, and advanced radars. The study challenges the long-standing practice of trying to eliminate interactions between, or "mutual coupling," between the antennas and amplifiers in these devices. Instead, the research suggests that by actively controlling and using this coupling, engineers can create more efficient and flexible wireless technology. 

By intentionally managing these interactions, the research achieved significant results. A key finding was a 92% increase in the operational frequency range of a wireless system, allowing it to work across a much wider band of frequencies. It also led to a 36% increase in the frequency steer envelope, which means the system can maintain its performance while directing its signal over a broader range of angles. 

Ultimately, the most important takeaway from this research is a call for a new way of thinking. Rather than seeing antennas and amplifiers as separate parts, the thesis argues that they should be designed as a single, integrated system. This holistic approach could pave the way for a new generation of wireless devices that are not only more efficient and powerful but also more compact and adaptable for the increasingly connected world.

Thesis available for public display 7 days prior to the defence at Aaltodoc.