Distributed Wavefront Shaping in Near-Field sub-1 THz Wireless Networks

In sub-terahertz (sub-THz) wireless networks, the radiative near-field regime can no longer be ignored. Indeed, this less-explored electromagnetic regime can provide unprecedented opportunities to tackle the long-standing challenges of sub-THz wireless communication, including using focused beams to combat higher propagation losses and self-healing beams that offer enhanced resilience against line-of-sight blockage. Nevertheless, our mathematical modeling and experimental study find that such favorable near-field properties can be observed only within a smaller range of the nominal near-field Fresnel regime. When attempting to extend this range, current literature suggests adopting transmit arrays with larger form factors, which may not be available in the environment or even hard and expensive to fabricate. In this study, we present the first mathematical modeling and experimental demonstration of distributed near-field beam shaping using multiple coordinated transmitting apertures, hence, increasing the effective near-field regime. Our modeling is built on a detailed understanding of near-field electromagnetics, Fourier optics, and wave optics.