| Project/Area Number |
63550033
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理計測・光学
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| Research Institution | National Astronomical Observatory |
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Principal Investigator |
KASUGA Takashi National Astronomical Observatory Research Associate, 電波天文学研究系, 助手 (70126027)
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| Co-Investigator(Kenkyū-buntansha) |
KAWABE Ryohei National Astronomical Observatory Research Associate, 電波天文学研究系, 助手 (10195141)
宮沢 敬輔 国立天文台, 野辺山宇宙電波観測所, 講師 (10134628)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1989: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | HEMT / Cryogenic Temperature / Microwave / Millimeter-wave / DX center / Light / Amplifier / Mixer / 低雑音アンプ |
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| Research Abstract |
There are some problems when the microwave HEMT amplifiers are cooled down to the cryogenic temperature. The experiment using 23GHz HEMT amplifier in the last year shows that noise temperature becomes lower and problems are nearly solved by applying red LED light to the HEMT chip. And We claimed that all chips in the amplifier must be illuminated for better stability and resetability and no hysteresis.
In this year we developed the cooted millimeter-wave HEMT mixer. This mixer has only one HEMT as a key component, and temperature and illumination effects are clearly examined. The input signal (43GHz) is fed through waveguide/antenna and stripline to a gate electrode and the local power (41.6GHz) through coaxial cable and stripline to a drain electrode. The IF output (1.4GHz) from the drain electrode is amplified by the ultra-low noise amplifier. This "drain" mixer can have a gain theoretically. The light from a room-temperature LED is fed through a optical-fiber. The whole is cooted down to the cryogenic temperature.
The cryogenically cooled HEMT mixer is thought to be a good candidate as a frontend of millimeter-wave radio telescopes. This experiment is the first one in the world. The mixer conversion loss 3.2 dB which value is lower than that of diode mixer was obtained at the room temperature. Large effects of cooting and illumination will be obtained.
HEMT used in the millimeter-wave region is very preliminary, and electric parameters between chips/lots change. Now we search the best matching circuit for each chip and mixer.
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