Smart beamforming techniques for “on demand” WPT

This chapter focuses on smart radiating solutions for wireless power transfer (WPT) purposes, being the energy-aware transmission of power the weakest and less efficient step in the entire link budget estimation. The exploitation of time as additional degree of freedom in the transmitting array synthesis makes time-modulated arrays (TMAs) potential candidate for future telecommunication applications, as WPT: their almost real-time ease of reconfiguration allows an agile and dynamic transmission of the signal/energy. Moreover, TMAs rely on a peculiar radiation phenomenon: the possibility to deploy additional radiating frequencies, besides the fundamental radio-frequency (RF) carrier, generated by the superposition of the carrier itself and the low frequency used to drive the nonlinear switches placed at each antenna port. This sideband radiation can be favorably exploited thus making TMAs multiharmonic radiators at the same time: a smart WPT procedure relying on this capability is demonstrated. The importance of a complete software tool, combining full-wave and nonlinear circuit techniques for the accurate estimation of TMAs complex regime, is also highlighted in the chapter.