Analysis of High-Frequency Atmospheric Windows for Terahertz Transmission Along Earth-Space Paths

The atmospheric absorption effect greatly increases the transmission loss of terahertz (THz) waves, which limits the transmission distance. In this article, with the support of sufficient antenna gain, a series of high-frequency THz transmission windows in the ground-satellite link are presented. First, the more ideal ground-based site is determined. Based on the path loss model and the layered transmission theory, the total path loss is obtained. Combined with signal transmit power, antenna gain, signal-to-noise ratio, and noise power, total usable bandwidths and transmission windows in the 0.2–15 THz corresponding to antenna gain from 0 to 100 dBi are given. By taking the high-altitude platform as a relay link, the usable transmission windows are also given. The first six transmission windows are identified as [0.4776–0.48645 THz], [0.4906–0.49975 THz], [0.6618–0.6811 THz], [12.1015–12.10355 THz], [12.10425–12.11285 THz], and [12.11505–12.14355 THz] bands against 100 dBi gain near 1 and 10 THz bands, respectively. Furthermore, the influence of ice clouds on the transmission characteristics is analyzed. The additional attenuation in the partial usable atmospheric window frequency range can reach 1.84 dB typical, which is directly related to the effective radius and shape of particles.