Propagation modeling and characteristic analysis of terahertz waves via high altitude platforms

Satellite-to-ground terahertz communication is limited by the power of signal source and antenna gain level, and has large path loss, which is difficult to implement. In this paper, a feasible scheme of satellite-to-ground terahertz communication using High Altitude Platforms (HAPs) as relay is presented, and the path loss on terahertz communication links is modeled and analyzed. Combined with the path loss model, the transmission loss along HAP-to-ground paths under different seasons and complex weather environment in Ali, Tibet, China is calculated. The results show that the transmission characteristics of terahertz waves in winter and summer are significantly different, mainly reflected in the number and bandwidth of usable atmospheric windows. Furthermore, the additional attenuation caused by the typical sand dust and ice cloud environment on terahertz band can reach 6.1 dB and 1.9 dB at the maximum respectively. With the aid of high gain antenna, the usable communication frequencies of the HAP-to-ground links in winter are significantly more than those in summer. When the transmitting and receiving antenna gain is 40 dBi respectively, the usable communication frequency can reach 1.35 THz in winter, while it is limited to less than 1 THz in summer, up to 0.493 THz.