One of the main challenges of beyond-5G wireless communications is the realization of energy-efficient high data-rate links. In this regard, wireless near-field links have been proposed as an alternative to most conventional wireless far-field links. Indeed, in the near-field region it is possible to generate electromagnetic waves with limited diffractive spreading, also known as localized waves, for which the link budget no longer obeys the Friis equation. However, radiating systems capable of generating localized waves in the mm-wave and terahertz (THz) range are lacking, and those available suffer from high costs and/or design complexity.
In this project, we propose to analyze, design, and experimentally validate mm-wave/THz radiating systems not only capable of generating localized waves, but also equipped of novel features with respect to the state of the art. Specifically, we aim to realize advanced radiating systems with both improved focusing efficiency and tunable properties. In both cases, the reference structures are leaky-wave antennas (LWAs), as they offer a low-cost, low-profile solution to realize planar radiating devices capable of generating localized waves. Among the various types of localized waves, we will focus on the generation of Bessel-like beams, as they retain exceptional focusing and power transport properties compared to other localized solutions.
In order to improve the focusing efficiency of current mm-wave and THz systems, here we wish to investigate the possibility of generating Bessel-Gauss beams through LWAs. Similar structures will be equipped of tunable elements to offer the possibility to reconfigure the beam shape by the application of an external driving voltage: in the millimeter-wave range, we will consider p-i-n diodes as tunable elements, whereas in the THz range, we will consider graphene sheets and/or liquid crystals. Full-wave numerical simulations and experimental campaigns are planned to validate the proposed theory.
