Dr. Takafumi Kojima Profile

Dr. Takafumi Kojima

at National Astronomical Observatory of Japan

SPIE Involvement:

Author

Publications (13)

SPIE Journal Paper | 23 June 2022

Digital calibration test results for Atacama Large Millimeter/submillimeter Array band 7+8 sideband separating receiver

Franco Curotto, Ricardo Finger, Takafumi Kojima, Kazunori Uemizu, Álvaro González, Yoshinori Uzawa, Leonardo Bronfman

JATIS, Vol. 8, Issue 02, 024004, (June 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.2.024004

KEYWORDS: Calibration, Receivers, Field programmable gate arrays, Astronomy, Analog electronics, Signal processing, Phase measurement, Double sideband modulation, Dynamical systems, Waveguides

Read Abstract +

Proceedings Article | 13 December 2020 Poster + Paper

Optical design of the 1.85-m mm-submm telescope in 210–375 GHz band

Yasumasa Yamasaki, Sho Masui, Masanari Okawa, Koki Yokoyama, Taisei Minami, Shota Ueda, Yutaka Hasegawa, Atsushi Nishimura, Toshikazu Onishi, Hideo Ogawa, Nozomi Okada, Kimihiro Kimura, Alvaro Gonzalez, Takafumi Kojima, Keiko Kaneko, Ryo Sakai

Proceedings Volume 11453, 114534H (2020) https://doi.org/10.1117/12.2561955

KEYWORDS: Optical design, Telescopes, Receivers, Mirrors, Clouds, Reflectors, Antennas, Optical instrument design, Device simulation, Optical simulations

Read Abstract +

Proceedings Article | 13 December 2020 Poster + Paper

Development of a wideband waveguide diplexer for simultaneous observation at 210-375 GHz

Sho Masui, Taisei Minami, Masanari Okawa, Yasumasa Yamasaki, Koki Yokoyama, Shota Ueda, Yutaka Hasegawa, Atsushi Nishimura, Toshikazu Onishi, Hideo Ogawa, Takafumi Kojima, Alvaro Gonzalez

Proceedings Volume 11453, 114534F (2020) https://doi.org/10.1117/12.2561355

KEYWORDS: Waveguides, Telescopes, Receivers, Observatories, Clouds, Astronomy, Oscillators, Waveguide modes

Read Abstract +

Proceedings Article | 13 December 2020 Poster + Paper

Design of all-in-one 2SB mixer for ALMA band 10

Yasunori Fujii, Takafumi Kojima, Matthias Kroug, Yoshinori Uzawa

Proceedings Volume 11453, 114533Y (2020) https://doi.org/10.1117/12.2562032

KEYWORDS: Waveguides, Oscillators, Electromagnetic simulation, Interfaces

Read Abstract +

Proceedings Article | 13 December 2020 Presentation + Paper

Wideband technology development to increase the RF and instantaneous bandwidth of ALMA receivers

Takafumi Kojima, Kazunori Uemizu, Hitoshi Kiuchi, Tomonori Tamura, Keiko Kaneko, Ryo Sakai, Akihira Miyachi, Wenlei Shan, Yoshinori Uzawa, Alvaro Gonzalez, Matthias Kroug, Takeshi Sakai

Proceedings Volume 11453, 114530P (2020) https://doi.org/10.1117/12.2561240

KEYWORDS: Receivers, Radio frequency circuits, Astronomy, Observatories, Heterodyning, Waveguides

Read Abstract +

Proceedings Article | 13 December 2020 Poster + Paper

Status of the East Asia ALMA development program: Towards the implementation of the ALMA development roadmap

Álvaro González, Takafumi Kojima, Wenlei Shan, Hitoshi Kiuchi, Yoshinori Uzawa, Daisuke Iono, George Kosugi

Proceedings Volume 11445, 1144538 (2020) https://doi.org/10.1117/12.2561603

KEYWORDS: Receivers, Telescopes, Antennas, Spectroscopy, Calibration, Software development, Superconductors, Integrated circuit design, Integrated circuits

Read Abstract +

Proceedings Article | 13 December 2020 Presentation + Paper

An SIS-mixer-based amplifier for multi-pixel heterodyne receivers

Yoshinori Uzawa, Takafumi Kojima, Yuto Kozuki, Yasunori Fujii, Akihira Miyachi, Tomonori Tamura, Shohei Ezaki, Wenlei Shan

Proceedings Volume 11453, 114530Q (2020) https://doi.org/10.1117/12.2563183

KEYWORDS: Amplifiers, Heterodyning, Receivers, Microwave radiation, Cryogenics, Frequency conversion

Read Abstract +

Proceedings Article | 13 December 2020 Poster + Paper

Development of receiver optics for ALMA bands 1 and 2, and possible synergies with ngVLA

Álvaro González, Keiko Kaneko, Ryo Sakai, Takafumi Kojima, Yoshinori Uzawa

Proceedings Volume 11453, 114533S (2020) https://doi.org/10.1117/12.2561595

KEYWORDS: Receivers, Waveguides, Plastic lenses, Additive manufacturing, 3D printing, Astronomy, Observatories, Product engineering, Astronomical imaging, Optical fabrication equipment

Read Abstract +

Proceedings Article | 9 July 2018 Paper

Technical achievements of the ALMA future receiver development program at the National Astronomical Observatory of Japan

A. Gonzalez, T. Kojima, M. Kroug, W. Shan, S. Asayama, D. Iono, T. Noguchi, S. Iguchi

Proceedings Volume 10708, 1070812 (2018) https://doi.org/10.1117/12.2312969

KEYWORDS: Receivers, Waveguides, Superconductors, Telescopes, Heterodyning, Terahertz radiation, Antennas

Read Abstract +

Proceedings Article | 9 July 2018 Paper

Development of a low-power cryogenic MMIC HEMT amplifier for heterodyne array receiver application

J. Liu, W. Shan, T. Kojima, X. Zhang, Z. Li, Y. Chen

Proceedings Volume 10708, 107082X (2018) https://doi.org/10.1117/12.2314356

KEYWORDS: Cryogenics, Field effect transistors, Amplifiers, Gallium arsenide, Receivers, Capacitors, Astronomy, Transistors

Read Abstract +

Proceedings Article | 9 July 2018 Paper

Overview of the East Asia ALMA development program

S. Asayama, A. Gonzalez, H. Kiuchi, T. Kojima, M. Kroug, W. Shan, G. Kosugi, D. Iono, S. Iguchi

Proceedings Volume 10708, 1070837 (2018) https://doi.org/10.1117/12.2313367

KEYWORDS: Receivers, Software development, Terahertz radiation, Spectroscopy, Observatories, Astronomy, Telescopes, Calibration, Data archive systems, Antennas

Read Abstract +

Proceedings Article | 6 July 2018 Paper

How do we design the interferometric system focused on the analog and digital backend and the correlator for scientifically valuable ALMA developments?

S. Iguchi, A. Gonzalez, T. Kojima, W. Shan, G. Kosugi, S. Asayama, D. Iono

Proceedings Volume 10700, 107002Y (2018) https://doi.org/10.1117/12.2312024

KEYWORDS: Data transmission, Analog electronics, Receivers, Interferometry, Antennas, Astronomy, Telescopes

Read Abstract +

Proceedings Article | 23 July 2014 Paper

ALMA band 10 (787-950 GHz): summary of the production of 73 receivers and first light results

Alvaro Gonzalez, Yasunori Fujii, Keiko Kaneko, Matthias Kroug, Takafumi Kojima, Koichi Kuroiwa, Akihira Miyachi, Kazumasa Makise, Zhen Wang, Shin'ichiro Asayama, Yoshinori Uzawa

Proceedings Volume 9153, 91530N (2014) https://doi.org/10.1117/12.2055598

KEYWORDS: Receivers, Polarization, Tolerancing, Astronomy, Antennas, Mirrors, Optical testing, Terahertz radiation, Superconductors, Niobium

Read Abstract +

Showing 5 of 13 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years