A STUDY ON 21 -GHz BAND DIRECT BROADCAST SATELLITE USING PHASED ARRAY ANTENNA-SYSTEM CONCEPT AND KEY TECHNOLOGIES TO COMPENSATE FOR RAIN ATTENUATION

摘要

Succeeding the direct broadcast satellite service in the 12-GHz band, we are studying an advanced broadcasting satellite systems using 21-GHz band. The 21-GHz band has a 600-MHz bandwidth and is expected to be the strong candidate to broadcast the wide-band program such as Super High-Vision. However, the rain attenuation in the 21-GHz band is very large compared to that in the 12-GHz band. In view of this, we need effective rain attenuation compensation techniques to achieve reliable 21-GHz band satellite broadcast services. We propose an onboard phased array antenna system that will increase radiation power only in rainy areas to compensate for the rain attenuation of the 21-GHz band. This paper describes an array-fed reflector antenna capable of concentrating the RF power to a narrow area using a small number of array elements. Additionally, it describes a newly developed 21-GHz band miniature TWT that has a small cross-sectional area used as the array element. Furthermore, we introduce a long block-length interleave transmission scheme as a new rain attenuation mitigation technique.