Abstract-Rain Attenuation in the Microwave-to-Terahertz Waveband

 Seishiro Ishii, Masahiro Kinugawa, Shunichiro Wakiyama, Shuji Sayama, Toshihisa Kamei

http://blog.scirp.org/computer-science-communications/wet/rain-attenuation-in-the-microwave-to-terahertz-waveband/

In recent years, there has been increased interest in the terahertz waveband for application to ultra-high-speed wireless communications and remote sensing systems. However, atmospheric propagation at these wavelengths has a significant effect on the operational stability of systems using the terahertz waveband, so elucidating the effects of rain on propagation is a topic of high interest. We demonstrate various methods for calculating attenuation due to rain and evaluate these methods through comparison with calculated and experimental values. We find that in the 90 – 225 GHz microwave band, values calculated according to Mie scattering theory using the Best and P-S sleet raindrop size distributions best agree with experimental values. At 313 and 355 GHz terahertz-waveband frequencies, values calculated according to Mie scattering theory using the Weibull distribution and a prediction model following ITU-R recommendations best agree with experimental values. We furthermore find that attenuation due to rain increases in proportion to frequency for microwave-band frequencies below approximately 50 GHz, but that there is a peak at around 100 GHz, above which the degree of attenuation remains steady or decreases. Rain-induced attenuation increases in proportion to the rainfall intensity.

Abstract-Experimental Comparison of Terahertz and Infrared Signaling in Laboratory-Controlled Rain

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• Jianjun Ma 
• , Francis Vorrius
• , Lucas Lamb
• , Lothar Moeller
• , John F. Federici

http://link.springer.com/article/10.1007%2Fs10762-015-0183-3

In order to analyze the impairments of terahertz (THz) and infrared (IR) links caused by attenuation through rain, THz and IR free-space communication channels at 625 GHz and 1550 nm, respectively, with a maximum data rate of 2.5 Gb/s have been developed in our lab. These two links are spatially superimposed and propagate through the same weather conditions. The performance of both channels is analyzed by measuring the power and bit error rates (BERs) in each link. A weather emulating chamber is designed that can generate controllable rain. Under the same conditions, attenuation by rain exhibits higher but comparable performance degradation in the THz channel. Analysis of power attenuation and BERs performance for both links is presented. Numerical simulations of THz and IR attenuation under different rain conditions are conducted and compared with experimental results.