Terahertz Channel Modeling Considering Near-to-Far Field Transition: Benefits & Challenges

Terahertz band (0.1-10 THz) communication is set to play a pivotal role in the advancement of subsequent generations of wireless technology by facilitating high data rates, ultra-secure transmission, high-resolution sensing, and low-latency links, among others. Nevertheless, the issues of low transmission power and high path loss necessitate large-aperture high-gain antennas, which can result in a considerably expanded near-field operational region. The distinctive mechanism of wave propagation within this region, as well as its transition to the far-field area, necessitates a comprehensive reevaluation of channel modeling. In this paper, we discuss the effects of antennas on path loss models and channel metrics while operating in both the near- and far-field regions. We present a detailed analysis of near-field propagation mechanisms, illustrating that an antenna-agnostic channel model is not feasible. Furthermore, we discuss the potential benefits and challenges associated with these regions.