Ka-band Earth-space propagation research in Japan

Karasawa, Yoshio; Maekawa, Yasunori

doi:10.1109/5.598407

Cited by 41 publications

(17 citation statements)

References 39 publications

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“…3(a), the data points observed at RISH are centered around the Jd type up to 10 dB down-link attenuation except for a small attenuation range of less than about 3 dB, while they approach the Jt type in a large attenuation range of more than 10 dB. These tendencies in small (<3 dB), middle (3-10 dB) and large (>10 dB) attenuation ranges are very similar to those found in the long term frequency scaling statistics between Ka-band N-Star beacon signal (19.45 GHz) rain attenuation and Ku-band BS broadcasting signal (11.84 GHz) rain attenuation at Neyagawa, Osaka in Japan (Karasawa and Maekawa 1997). The frequency scaling relationship between N-Star and BS was, however, obtained from the equi-probability values of their attenuation measured in different propagation paths and observational instances, while the present relationship between up-and down-link attenuation is detected directly from the instantaneous observational values measured on the same propagation path at the same time.…”

Section: Frequency Scaling Factors For Various Attenuation Rangessupporting

confidence: 78%

“…It is well known that rain attenuation of radio wave is significant in satellite communications using frequencies of higher than 10 GHz such as Ku band (14/12 GHz) and Ka band (30/20 GHz) (e.g., Arbesser-Rastburg and Brussaard 1993, Dintelmann et al 1993, Bauer 1997, Karasawa and Maekawa 1997. Rain attenuation may become very severe even for Ku-band radio waves in heavy rain regions like the tropics (Pan et al 2001, Pan andAllnutt 2004).…”

Section: Introductionmentioning

confidence: 99%

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Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

Maekawa

Fujiwara

Shibagaki

et al. 2006

Journal of the Meteorological Society of Japan

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This study investigates the effects of tropical rainfall on the Ku-band satellite communications links that connect Research Institute for Sustainable Humanosphere (RISH), Kyoto University in Japan to Equatorial Atmosphere Radar Observatory (EAR; 0.2 S, 100.3 E) in Indonesia, using the satellite Superbird C (144 E in orbit). Rain attenuation of the up-and down-link radio wave signals is, for the first time, obtained at the same time in the tropics, monitoring each signal level that has been received at both stations in Japan and Indonesia for the past three years from 2003 to 2005. The up-link attenuation at each station can be estimated from the down-link signal level measured at its opposite station, because SCPC (Single Channel Per Carrier) signals used in this experiment are linearly amplified without saturation of the satellite transponders. At EAR in Indonesia, a slightly larger attenuation ratio between up and down links is statistically presented for the attenuation range of higher that 10 dB, suggesting the effects of smaller raindrop size distributions (DSD) than observed at RISH in Japan. This tendency is more conspicuous in the rainfall events when the observed attenuation shows only one peak in its time series, indicating the effects of simple convective precipitating clouds with one single cell. At RISH in Japan, a larger difference between worst month and yearly average statistics is found, due to a larger variation of the ground temperature that affects the slant-path length during the seasons, although the yearly average time percentages as such are larger at EAR than RISH up to the up-link attenuation of 15 dB. Using time percentages of their local rainfall rates, fairly good agreement is found between the observations and the ITU-R (International Telecommunication Union-Radiocommunication Sector) predictions for both locations. At EAR in Indonesia, however, the time percentages of the attenuation of more than 10 dB become significantly smaller than those predicted by the ITU-R methods for both up and down links. This indicates the remarkable reduction of equivalent path lengths down to about 2 km, caused by a fairly localized structure of convective precipitating clouds. Simultaneous X band radar observations have revealed that intense echo cores of typical rain cells causing severe attenuation are confined to about 2 km along the propagation path. This result, which seems rather small even compared with those obtained in other tropical observation sites, may be attributed to unique features of the EAR site that is located in a highland basin 865 m above the mean sea level and frequently observes simple precipitating clouds with a single cell.

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Section: Frequency Scaling Factors For Various Attenuation Rangessupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Effects of Tropical Rainfall to the Ku-Band Satellite Communications Links at the Equatorial Atmosphere Radar Observatory

Maekawa

Fujiwara

Shibagaki

et al. 2006

Journal of the Meteorological Society of Japan

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“…Other investigators have also reported this orientation [4]- [12]. One group using a multiparameter radar reported on the existence of vertically oriented ice crystals [13]; this existence will help mitigate the depolarization due predominately to horizontally oriented crystals [2], [3], [7], [8], [11].…”

Section: Introductionmentioning

confidence: 89%

Mitigation of rain and ice particle cross polarization at RF for dual circularly polarized waves

Tomìyasu

1998

IEEE Trans. Antennas Propagat.

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On millimeter-wave satellite-to-ground links encountering moderate rain and ice particles, RF mitigation of atmospheric cross-polarization effects on circularly polarized (CP) waves can be achieved by inserting a passive fixed phase delay in the vertical component of the received electric field introduced prior to an orthomode transducer (OMT) in the receiver. This passive phase shifter and the OMT can be combined into a single microwave structure and its performance is discussed.

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“…This requires higher frequencies, such as Ku, Ka and V band for satellite communication. Rain attenuation effect on microwave propagation is severe above 10 GHz frequency which has been extensively dealt with experimental observations from temperate regions (Rastburg and Brussaard, 1993;Dintenmann et al, 1993;Bauer, 1997;Karasawa and Maekawa, 1997) as well as over tropical regions (Pan et al, 2001;Pan and Allnutt, 2004;Maitra et al, 2007Maitra et al, , 2012Adhikari et al, 2011;Das et al, 2010aDas et al, , 2013. However, the information on the depolarization effect on these frequency bands is limited in the tropical region.…”

Section: Introductionmentioning

confidence: 97%