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dB][28log20100fL(2)Where; L0 represents the propagation loss at reference distance d0 = 1 m; n represents the pass loss coecient (a model parameter); d denes the inter-antenna distance between the transmitter and receiver; and f represents frequency in MHz.e calculated path loss coecients in the line-of-sight (LoS) situation showed slightly greater values (n = 2.1～2.4) as compared to the free space path loss (n = 2). ey become larger in the non-line-of-sight (NLoS) situation (n = 3.1～3.3). It was conrmed that contributing factors in the NLoS situation — reection from building walls and diraction from rooops — were a signicant portion to the received signal. e authors are planning to utilize these results in the future development of radiocommuni-cation devices, typically for link budget design and interfer-ence evaluation. A part of the results, short-distance outdoor propagation models, was submitted as a proposal to the corresponding group 3K-6 in WP3K of ITU-R SG3.3Research on terahertz wave propagation[4][5]NICT is now promoting research on characterization of propagation properties in the 300 GHz band with the goal of realizing a radio communication system that uses the 275–325 GHz band. e objectives of the research are related to AI 1.15 of WRC-19, i.e. Studies towards an identication for use by administrations for LMS and FS applications operating in the frequency range 275–450 GHz. is section describes indoor propagation character-istics in the 300 GHz band and the propagation model applicable to this band.Server-to-server high speed data communication inside a data center is under review as one of the candidate ap-plications of broadband wireless communication systems that can take advantage of the frequencies at and around 300 GHz. e relation between propagation loss and transmission distance was investigated within a server room environment (Fig. 9), where the transmitter and re-ceiver were assumed to be installed on top of the server chassis. e metallic server chassis are basically arranged in a straight line, however, their installation intervals are FiF11Path loss measurement results in data center environment(Copyright(C)2017 IEICE, [4] Fig. 5)1510508090100110120d (m)Path loss (dB)Path loss exponentN= 20.2FiF10　Positions of metallic server(Copyright(C)2017 IEICE, [4] Fig. 2)FiF9　Data center environment(Copyright(C)2017 IEICE, [4] Fig.1)2 Terrestrial Communication Technology Research and Development22　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)