[S-GD01] 全球統合測地観測システム：変動する地球を監視する測地インフラ

[SGD01-P12] 次世代高感度マイクロ波放射計の開発-初期観測成果-

*市川 隆一¹、氏原 秀樹¹、佐藤 晋介¹、太田 雄策²、宮原 伐折羅³、宗包 浩志³、長崎 岳人⁴、田島 治⁵、荒木 健太郎⁶、田尻 拓也⁶、瀧口 博士⁷、松島 健⁸、松島 喜雄⁹、桃谷 辰也¹⁰、宇都宮 健志¹⁰ (1.情報通信研究機構、2.東北大学、3.国土地理院、4.理化学研究所、5.京都大学、6.気象研究所、7.宇宙航空研究開発機構、8.九州大学、9.産業技術総合研究所、10.日本気象協会)

We have started to develop a next-generation microwave radiometer to be used in millimeter-wave spectroscopy for the high-resolution and high-precision monitoring of water vapor behavior. The new radiometer will be suitable for not only space geodetic techniques such as VLBI and GNSS, but also field measurements to monitor, for example, volcanic activities and cumulonimbus cloud generation. The planned front-end system for our new microwave radiometer has a wide bandwidth feed of 20–60 GHz. A signal from the feed is separated into two linear orthogonal polarized signals using an orthomode transducer (OMT); one is in the 20–30 GHz feed and the other is in the 50–60 GHz feed. We are now planning to cool the wideband feed, OMT, and LNA for each signal at 77 K using a Stirling cryocooler to improve the signal-to-noise ratio. We assembled a room-temperature 20–30 GHz receiver without the cooling system until the middle of 2019 as a first step of our development. We implemented the new receiver into the 3.7 m dish at Okinawa Electromagnetic Technology Center, National Institute of Information and Communications Technology (NICT), and carried out the first measurements using this receiver for validation tests in October 2019. Quick-look data obtained by the new receiver shows good power signals for the expected receiving band of 18–28 GHz. We are now developing another receiver for a higher band of 50–60 GHz, and we are going to implement the second one into the new prototype radiometer by the end of this fiscal year.