Akira Akaishi

University of Electro-Communications

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Toshio Asai

National Institute of Information and Communications Technology

Ryutaro Suzuki

Tohoku University

Kazuyoshi Kawasaki

National Institute of Information and Communications Technology

Mitsugu Ohkawa

National Institute of Information and Communications Technology

Takashi Takahashi

The University of Tokyo

Jun Nakamura

University of Electro-Communications

Morio Toyoshima

National Institute of Information and Communications Technology

Yoshiyuki Fujino

Toyo University

Hirofumi Matsuzawa

Mitsubishi Electric (United States)

T. Takahashi

Tohoku University

Cooperative Institutions

National Institute of Information and Communications Technology

Mitsubishi Electric (Japan)

Ministry of Internal Affairs and Communications

Mitsubishi Group (Japan)

Tohoku University

Mitsubishi Electric (Germany)

Mitsubishi Electric (United States)

The University of Tokyo

University of Electro-Communications

Japan Science and Technology Agency

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Research and Development of Scanning Variable Spot Beam Antenna for Adaptive Satellite Communications -- Adaptive Communications System to improve Ka-band operating ratio

IEICE Technical Report; IEICE Tech. Rep. (2010)

Akira Akaishi Ryutaro Suzuki Yoshiyuki Fujino Yozo Shoji Sumiyoshi Hideo

Communications satellite

Ka band

S band

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Citations (1)

Communications Satellite R&D for the Next 30 Years: Follow-On

20th AIAA International Communication Satellite Systems Conference and Exhibit (2002)

Takashi Iida Yoshiaki Suzuki Akira Akaishi

Communications satellite

Satellite broadcasting

10.2514/6.2002-1972

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Citations (2)

Development results of partial model of a Ka-band active phased array antenna for gigabit satellite

International Journal of Satellite Communications (1999)

Shiro Kitao Hiromasa Nakaguro Hitoshi Mizutamari Akira Akaishi Ryoichi Imai

The high data rate and global satellite communication systems are expected to be an improvement agenda to the social and economic activities in the 21st century. The experimental high data rate (gigabit) communications satellite is required to face the technological challenges of the future growing multi-media applications. For this gigabit communications system, a Ka-band scanning spot beam antenna (SSBA) which realizes multiple beam forming is required. CRL and MELCO have been developing Ka-band active phased array antenna (APAA) for the SSBA as one of the most important and challenging technology. An APAA has been developed mainly for radar systems for many years. CRL and MELCO are investigating and developing the direct radiating APAA for communication satellites which can operate under wide frequency band in Ka-band. This paper describes the preliminary study results of the Ka-band APAA for gigabit satellite and the radiation performances of the partial experimental model of Ka-band APAA with two multiple beams to both transmit and receive signals. The partial model includes the active MMIC device such as HPA (high power amplifier), LNA (low noise amplifier) and PS (phase shifter), and multi-layered BFN (beam forming network) as key components. Performances such as radiation pattern, beam scanning performance and input–output performance have been measured. We also verified that the REV (rotating element electric-field vector) method was effective for pattern calibration. Copyright © 1999 John Wiley & Sons, Ltd.

Ka band

Communications satellite

Gigabit

10.1002/(sici)1099-1247(199903/06)17:2/3<187::aid-sat634>3.0.co;2-v

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Characteristics of scale models of large deployable mesh reflector antennas for mobile communications satellites

Space Communications (1993)

Akira Akaishi Teruaki Orikasa Kanshiro Kashiki Teruki Okamoto Y. Otsu

In the land mobile satellite system (LMSS) using a geostationary platform (GPF), a 30 m diameter satellite antenna is desirable for small portable terminal communications. SCR has adopted two deployment types of antenna structure, the Hexa-Link Truss reflector and the Tetra-Triagonal Prism Truss (TETRUS) reflector, and has developed scale models of them. Both of them represent important aspects of large satellite antenna technology. This paper describes the SCR outline of a land mobile satellite communications system and the experimental results of the scale models. This research establishes the basic technical information necessary for the development of a 30 m diameter antenna and a conceptual GPF design

Reflector (photography)

Communications satellite

Cassegrain antenna

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Citations (2)

Demonstration of separation of multiple beams using quadrant detector in optical beamforming for receiving antenna

Eisuke Haraguchi Hitomi Ono Junya Nishioka Toshiyuki Ando Amane Miura

To provide a satellite communication system with high reliability for social infrastructure, building flexible beam adapting to change of communication traffic is needed. Optical Beam Forming Network (OBFN) has capability of broadband transmission and small light construction. In OBF for Receiving Antenna, the function of separating multiple beams, which come simultaneously from different directions, is necessary. We use partition detector for detecting multiple optical beams spatially separated, which are superimposed the RF signal from different directions. In this paper, it is estimated that the isolation between two beams is over 21.6 dB with more than 37 elements.

Light beam

10.1109/icsos.2017.8357223

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Citations (0)

Matching and Visualization Tool to Support Encounters between Data Providers and Users

IEICE Technical Report; IEICE Tech. Rep. (2019)

Teruaki Hayashi Ando Aki Satoshi Tachibana Akira Akaishi Yukio Ohsawa

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Propagation Measurement for Mobile Satellite Communications Using WINDS at The Coast of Japan Sea of Western Japan

IEICE Technical Report; IEICE Tech. Rep. (2017)

Tomoshige Kan Takahashi Takashi Kazuyoshi Kawasaki Akira Akaishi Toshio Asai

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Effect of Water on the Manifestation of the Reaction Selectivity of Nitrogen-Doped Graphene Nanoclusters toward Oxygen Reduction Reaction

ACS Omega (2019)

Haruyuki Matsuyama Akira Akaishi Jun Nakamura

We investigated the selectivity of N-doped graphene nanoclusters (N-GNCs) toward the oxygen reduction reaction (ORR) using first-principles calculations within the density functional theory. The results show that the maximum electrode potentials (UMax) for the four-electron (4e-) pathway are higher than those for the two-electron (2e-) pathway at almost all of the reaction sites. Thus, the N-GNCs exhibit high selectivity for the 4e- pathway, that is, the 4e- reduction proceeds preferentially over the 2e- reduction. Such high selectivity results in high durability of the catalyst because H2O2, which corrodes the electrocatalyst, is not generated. For the doping sites near the edge of the cluster, the value of UMax greatly depends on the reaction sites. However, for the doping sites around the center of the cluster, the reaction-site dependence is hardly observed. The GNC with a nitrogen atom around the center of the cluster exhibits higher ORR catalytic capability compared with the GNC with a nitrogen atom in the vicinity of the edge. The results also reveal that the water molecule generated by the ORR enhances the selectivity toward the 4e- pathway because the reaction intermediates are significantly stabilized by water.

Nanoclusters

10.1021/acsomega.9b00015

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Citations (16)

Fundamental study on application of Imaging Reflector Antenna to onboard antenna for maritime broadband satellite communications

IEICE Technical Report; IEICE Tech. Rep. (2016)

Daisuke Takahashi Amane Miura Teruaki Orikasa Akira Akaishi Hajime Fukuchi

Communications satellite

Cassegrain antenna

Reflector (photography)

Antenna rotator

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