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arXiv · 2105.13605

Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Corrugated horn & Optics covering 210-375 GHz band

Yasumasa Yamasaki·Sho Masui·Hideo Ogawa·Hiroshi Kondo·Takeru Matsumoto·Masanari Okawa·Koki Yokoyama·Taisei Minami·Ryotaro Konishi·Sana Kawashita·Ayu Konishi·Yuka Nakao·Shimpei Nishimoto·Sho Yoneyama·Shota Ueda·Yutaka Hasegawa·Shinji Fujita·Atsushi Nishimura·Takafumi Kojima·Keiko Kaneko·Ryo Sakai·Alvaro Gonzalez·Yoshinori Uzawa·Toshikazu Onishi
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Abstract

The corrugated horn is a high performance feed often used in radio telescopes. There has been a growing demand for wideband optics and corrugated horns in millimeter and submillimeter-wave receivers. It improves the observation efficiency and allows us to observe important emission lines such as CO in multiple excited states simultaneously. However, in the millimeter/submillimeter band, it has been challenging to create a conical corrugated horn with a fractional bandwidth of ~60% because the wavelength is very short, making it difficult to make narrow corrugations. In this study, we designed a conical corrugated horn with good return loss, low cross-polarization, and symmetric beam pattern in the 210-375GHz band (56% fractional bandwidth) by optimizing the dimensions of the corrugations. The corrugated horn was installed on the Osaka 1.85-m mm-submm telescope with the matched frequency-independent optics, and simultaneous observations of 12CO, 13CO, and C18O (J = 2-1, 3-2) were successfully made. In this paper, we describe the new design of the corrugated horn and report the performance evaluation results including the optics.

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Yasumasa Yamasaki, Sho Masui, Hideo Ogawa, Hiroshi Kondo, Takeru Matsumoto, Masanari Okawa, Koki Yokoyama, Taisei Minami, Ryotaro Konishi, Sana Kawashita, Ayu Konishi, Yuka Nakao, Shimpei Nishimoto, Sho Yoneyama, Shota Ueda, Yutaka Hasegawa, Shinji Fujita, Atsushi Nishimura, Takafumi Kojima, Keiko Kaneko, Ryo Sakai, Alvaro Gonzalez, Yoshinori Uzawa, Toshikazu Onishi. 2021-05-28. Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Corrugated horn & Optics covering 210-375 GHz band. https://doi.org/10.1093/pasj%2Fpsab062

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