THz atmospheric propagation measurement system of CRIRP

The trend of higher frequency band than microwave and millimeter wave used in various regions, ultrafast broadband communication and high accuracy imaging application, etc., calls for the development of the Terahertz (THz) technology. Unlike the hot concentration on the study of the THz sources and detectors, the study of the propagation characteristics of THz wave in the atmosphere is relatively rare. The measurements of atmospheric absorption are the most important research works in advance. CRIRP (China Research Institute of Radiowave Propagation) build an atmospheric propagation measurement system in the frequency band of 0.26–0.34THz. The system comprises of a transceiver front, a Quasi-Optical Circulator system and software for the signal receiving and data recording. The system will be operated in a long-term schedule for the analysis of the THz atmospheric propagation effects which can be concluded into two categories: the atmospheric effect including the absorption attenuation and scintillation caused by the atmospheric molecules and atmospheric turbulence along the path, and the effect caused by the small particles (rain, fog, aerosol, etc.) in atmosphere. The system has been set up between two buildings in CRIRP, Qingdao, China, and the signal will experience a 150m round trip which makes the path length become 300m. This is a THz system aims not only at the rain attenuation effects but also the general effect of the atmosphere and the particles in it. The investigation based on the system is the foundation of various future applications of THz wave in troposphere.