[S-GD01] Geodesy and Global Geodetic Observing System

[SGD01-24] Development of Wideband Receiver for Nobel Ground-based Microwave Radiometer -field experiments of the new 16-58 GHz wide-band receiver-

*Ryuichi Ichikawa¹, Hideki Ujihara¹, Shinsuke Satoh¹, Yusaku Ohta², Basara Miyahara³, Hiroshi Munekane³, Taketo Nagasaki⁴, Osamu Tajima⁵, Kentaro Araki⁶, Takuya Tajiri⁶, Hiroshi Takiguchi⁷, Takeshi Matsushima⁸, Nobuo Matsushima⁹, Tatsuya Momotani¹⁰, Kenji Utsunomiya¹⁰ (1.National Institute of Information and Communications Technology, 2.Tohoku University, 3.Geospatial Information Authority of Japan, 4.RIKEN, 5.Kyoto University, 6.Meteorological Research Institute, 7.Japan Aerospace eXploration Agency, 8.Kyushu University, 9.National Institute of Advanced Industrial Science and Technology, 10.Japan Weather Association)

Keywords:Water Vapor, microwave radiometer, Wideband Receiver

We are developing 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 such as monitoring volcanic activities and cumulonimbus cloud generation. We assembled a room-temperature 20-30 GHz receiver without the cooling system in 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 first measurements using it for a validation test in October 2019. So far we have developed a new front-end module including the OMT and a new wideband feed by early December of 2020. The prototype of the complete receiver system has a wide-bandwidth feed of 16-58 GHz for measuring two frequency bands of 16-28 GHz (H₂O) and 50-58 GHz (O₂). We are now carrying out test measurement in order to evaluate the performance of the new receiver system. Although the experiment schedule for the validation of the new receiver is still uncertain owing to the COVID-19 pandemic, we are going to perform the experiments this fiscal year of 2020. After the validation measurements, we will install the receiver into the 90 cm dish or 1.8 m dish antenna and will start field measurements using the new receiver next fiscal year. Since the spatial resolution of the receiver depends on both dish size and distance between measurement site and object, we expect to detect various scales of water vapor behaviors. We will compare the results of the field experiments with those of tropospheric delay measurements using the low-cost multi-GNSS receivers and the GNSS Earth Observation Network (GEONET) System of the Geospatial Information Authority of Japan (GSI).