• field shaping
• metasurface
• MRI
• radiofrequency
• sensing
• wpt

Low-frequency electromagnetic fields (EMF) manipulation through metasurfaces has
emerged as a pivotal research area with significant implications for sensing technologies,
wireless power transfer (WPT), and magnetic resonance imaging (MRI). This dissertation
presents an extensive investigation about the design, theoretical principles, and experimental
validation of magnetic metasurfaces, bidimensional structures specifically conceived to
interact with and modulate the magnetic component of EMFs in the near-field domain. By
tailoring the interaction between metasurfaces and electromagnetic waves, these advanced
materials provide unparalleled control over field distributions, enabling innovative solutions
across various technological domains.
The study is structured around two principal types of metasurfaces: static and actively
reconfigurable. More in detail, Chapter 1 provides a historical and technical overview,
detailing the evolution of metasurfaces from three-dimensional metamaterials to compact two
dimensional configurations. It highlights the emerging role of metasurfaces in various key
applications, including sensing, energy transfer systems, and biomedical imaging.
Chapter 2 examines static metasurfaces, characterized by fixed electromagnetic properties.
The analysis of these structures employs two theoretical frameworks: the Biot-Savart law and
elementary magnetic dipole theory. The implemented case studies explore their use in
advanced sensing and ultra-focused WPT applications, respectively, demonstrating their
ability to reshape near-field magnetic distributions and improve the overall system efficiency.
Experimental validations confirm the robustness of these models.
Chapter 3 shifts the attention to reconfigurable metasurfaces, integrating electronically
adjustable components such as varactor diodes and digitally controlled capacitors to enable
dynamic adaptability. These metasurfaces allow real-time manipulation of magnetic field
distributions, making them a promising tool for advanced WPT and MRI applications where
operational conditions vary. Part of the research detailed in this chapter was conducted during
a 7-month research period as a visiting research scholar at the Fraunhofer MEVIS research
center in Bremen, Germany (1 June – 22 December 2023). This part of the work specifically
focused on developing reconfigurable metasurfaces tailored to enhance MRI systems,
particularly in optimizing field uniformity and improving the signal-to-noise ratio (SNR) in
dynamic imaging scenarios.
Throughout the dissertation, a consistent emphasis is placed on bridging theoretical
approaches and practical implementation. Numerical simulations guide the metasurfaces
design, while experimental validations, conducted on prototypes fabricated through PCB
technology, confirm their effectiveness in real-world scenarios.
Throughout this thesis, the main objective consists in outlining a path that, starting from
general notions about metasurfaces, focuses specifically on magnetic metasurfaces. Particular
attention is given to the distinctive characteristics of static metasurfaces, which are well-suited
to applications with stable operating conditions, and to reconfigurable metasurfaces, which are
fundamental for dynamic and adaptable environments.
While research on metasurfaces is well-advanced, several application areas still require further
exploration. This thesis aims to serve as a foundational reference for the integration of
magnetic metasurfaces into real-scenario devices, spanning from industrial to medical
scenarios.