A study on uplink (30 GHz) rain attenuation characteristics and up- and downlink available time percentages in Ka-band satellite communication

Using the CS-2 and CS-3 beacon levels (19.45 GHz) observed for the past 6 y ears, this paper discusses the time percentages of up- and downlink attenua tion when the signal is transmitted from the Osaka Neyagawa to Tokyo Setaga ya station via satellite. The uplink attenuation in the 30-GHz band is infe rred in a more realistic manner by selecting a relevant kind of raindrop si ze distribution (DSD) for each rainfall event from three representative typ es, namely, Jd (drizzle), MP (standard), and Jt (thunderstorm), based on cr oss-polar phase measurement at each event. The resulting time percentages o f the uplink attenuation tend to decrease by about 0.005% for attenuation l arger than 20 dB (time percentages < 0.05%) due to possible effects of the Jt-type DSD, compared with those inferred by the MP-type DSD only. This ten dency is also found in up- and downlink attenuation of nearly 30 dB. The ti me percentages of bidirectional up- and downlink attenuation between the Ne yagawa and Setagaya stations show a characteristic difference of about 50%, depending on the transmission directions each year, but they have nearly t he same long-term statistics over the 6 years. Also, the time percentages o f up- and downlink attenuation of between 4 and 5 dB increase by about 0.1% due to the probability of simultaneous occurrence of the attenuation betwe en the two stations, compared with those inferred with this simultaneous oc currence neglected. (C) 2000 Scripta Technica.