I am interested in the development of efficient, rigorous and general-purpose procedures, based on the Harmonic balance technique, for the circuit level analysis and design of entire RF front-ends, integrated with their antennas. The main goals are: energy efficiency, miniaturization and integration for future distributed applications. These techniques are in fact indispensable for the pervasive exploitation of modern wireless systems that need integrating energy collection, sensing, identification and localization. In this context, with a collaboration of my research group with the microelectronics unit of the University of Bologna, I have implemented innovative solutions of multi-band rectifying antennas capable of capturing electromagnetic energy from the environment, to efficiently treat the collected energy for its immediate or future use. I have also studied very novel RF-to-DC dynamic converters, allow to operate in multi-mode, starting from ultra-low power to manage both the wake-up radio and the main power-hungry radio. These activities have been demonstrated in various scientific contributions since 2009 and constitute the deliverables of several National and International research projects. In particular, we have developed quite a few compact multiband rectennas (rectifying antennas) not only on traditional substrates but also experimenting new materials, such as: various fabrics for both insulators and conductors. Some of these original results have been subject of an international patent. I have specifically designed magneto-dielectric materials, EM characterized for wearable applications.
From the transmitter side of the RF system I have developed smart radiators for realizing multi-beam antennas by modulating the RF signal with a slow signal (TMA). These techniques have been demonstrated also for innovative RFID readers capable not only to identify but also to locate and track objects and people in harsh EM indoor environments. (Furthermore, I have studied novel excitation techniques, based on duty-cycling of the RF excitation to minimize the energy per bit thus enabling the wake-up radio operations at long distances.
Another area of interest concerns the modelling of entire RF links at the circuit level, both SISO and MIMO, including the modelling of the radio channel and the actual layout of the antennas among the descriptive blocks. I have developed a procedure to define new figures of merit that include both the performance of the nonlinear subsystem and those of the radiating parts, in order to formulate the specifications of an RF system directly in terms of performance in the far field, accounting for a realistic prediction of the radio channel. This enable to model interactions between antenna and front-end in such a way that the impact on the overall system behaviour can be actual connection can be predicted with extreme precision. In this research field, I have also developed tools for neural networks of custom sub-systems, derived from their electromagnetic simulation.
Recently I have been dedicated to the development of wireless power transmission (WPT) systems, exploiting EM techniques for both near-field and far-field transfer mechanism, for different operating frequencies and power levels. I am studying general purpose solutions to integrate energy and data transfer for industrial applications and for the non-trivial problem of “on the move” WPT which is a highly relevant topic for EV vehicles recharging for civil and industrial application. I have obtained very interesting solutions for keeping a flat efficiency regardless of the vehicle position. Novel system configurations for power levels higher than > 100 W have been obtained with a system based on reactive coupling that is powered and controlled by transmitter and receiver systems exploiting the new GaN technology. Accurate circuit models of both the active and the passive parts have been derived, by means of a general purpose procedure, to enable system optimization based on its actual and dynamic terminations, rather than on unrealistic reference ones. I have developed a fully integrated system for high power transfer, as high as 1 kW, to rotating arms, foreseen as a strategic feature for industrial environments. In this case I have also demonstrated the simultaneous transmission of power and data through a passive sensing technique. This system has obtained a US patent in 2017.
Funding for these projects comes from both public and private, national and international entities such as: projects funded by the European community under the VII program and the ARTEMIS and EXCEL platforms, the European space agency (ESA) the MIUR, COST IC1301 action, from the European Regional Development Fund POR-FESR, the Ministry of Defense and several private companies such as IMA spa, Ducati Energia, Nubila and Alstom.
