Abstract
This paper presents wideband channel measurements for indoor Non-Line-of-Sight (NLoS) fixed links operating at sub-Terahertz (sub-THz) frequencies (92-110 GHz) with single scattered reflections. Seemingly "smooth" surfaces generate substantial internal multipath causing frequency selective scattered reflections owing to the short wavelength. Unlike specular reflections, no single well-defined reflection point aligns the incidence angle (θi) and reflection angle (θr) to form the lowest path loss. This means that the scattering effect of the reflective surface gives reason to search for the best angular alignment of the Receiver (Rx) antenna given a specific angle from the Transmitter (Tx) antenna. The wideband effective Radar Cross Section (RCS) is derived and computed based on the bi-static radar equation, which specifically accounts for the effect of alignment angle on the defined frequency selective RCS. The measurements reveal alignment-variant angular scattering from large-scale discontinuities such as wall partitions, television screens and metallic reinforcement studs, offering valuable insights for the design and deployment of future wireless communications systems operating in the sub-THz band.