A Novel 3-D Printed Dual-Port Rectenna for Simultaneous Energy Harvesting and Backscattering of a Passively Generated UWB Pulse

This work presents the design and characterization of a new compact rectenna system, fully three-dimensional (3-D) printed on a low-cost material, the polylactic acid (PLA). The rectenna consists of a patch-like antenna, with two orthogonal excitation ports, suitably designed to achieve both ultra-high-frequency (UHF) and ultra-wideband (UWB) cross-polarized radiation performance. The first port harvests multi-tone RF power at UHF, around 2.47 GHz (for the present case 8 equally spaced non-synchronized tones are used); the second port backscatters the intermodulation (IM) products generated by the rectifier, realizing a quasi-UWB pulse. The rectifier consists of a single-diode embedded into two linear subnetworks: one, connecting the UHF port and the diode, is co-designed to ensure dc-block and rectifier-antenna matching in the UHF band; the second one combines a high-pass filter, connecting the diode and the UWB port, to backscatter the passive pulse, and a dc path to collect the converted dc power. The 3-D etching of the low-cost substrate is optimized to obtain antenna performance comparable to those achieved with specialized RF materials. The system design is carried out by integrating full-wave and nonlinear simulations with the manifold goal of minimizing the overall footprint, ensuring UWB-mask-compatible radiated spectra and RF-to-dc conversion efficiency. A 3-D printed prototype has been realized and experimentally characterized. With a total received power of -15 dBm, equally distributed over eight tones spaced by 1 MHz, a quasi-UWB pulse power peak of about 80 nW has been demonstrated.