Exploitation of Harmonic Generation in Time-Controlled Frequency-Diverse Arrays for WPT

This work presents a novel and detailed harmonic analysis of frequency-diverse arrays (FDAs) when a pulsed regime is adopted to resolve the typical range–angle coupling of their radiation mechanism. This analysis demonstrates the positive exploitation of the harmonic generation of time-controlled FDAs when its use as smart energy sources for wireless power transfer applications is envisaged: in this context, several pulse waveforms are compared and the delicate tradeoff between the minimization of the power dispersed among out-of-band harmonics and the confinement of the illuminated region of space is deeply discussed. The triangular-shaped pulse combined with its repetition frequency identical to the constant frequency spacing among the antennas results to be the most promising choice. The analytical results are supported by measurements carried out in a realistic scenario with a four-monopole planar array operating at 1.8 GHz.