Low power Ka-band transmitters on Earth observation satellites

Low power Ka-band transmitters on Earth observation satellites
by Staff Writers
Tokyo, Japan (SPX) Feb 22, 2023

Axelspace Corporation has successfully developed a Ka-band radio for Earth observation microsatellites. The radio operates with less than half the power consumption of conventional radio. The collaborative research was jointly developed with Tokyo Institute of Technology (Tokyo Tech). With key collaborators Atsushi Shirane of the Laboratory for Future Interdisciplinary Research of Science and Professor Kenichi Okada and Assistant Professor Takashi Tomura of Department of Electrical and Electronic Engineering.

Earth observation data from microsatellites is attracting attention for a multitude of applications. Such as smart agriculture, environmental monitoring, disaster prevention, and disaster response. Demand for this data will increase in the future. More efficient mechanisms for transmitting data from space to Earth are needed.

The radio equipment typically used on microsatellites for earth observation have limitations. This is especially with compatibility between capturing and data communication. This issue arises because the direction of image capture and antenna communication do not match (attitude control). Large earth observation satellites in the several-ton class mount multiple types of antennas.

They can use different antennas depending on the distance from the ground stations. Or mechanical gimbals combined with controllable directivity phased array radios. Thus, allowing the large satellite to avoid conflicts in attitude control. However, microsatellites have a significant decrease in the storage space and the power. Presenting a unique and difficult challenge to adopt the above methods into microsatellites.

Advances in sensor technology and data services require today's Earth observation missions have faster communications. This downlink must achieve a large amount of data transmission in shorter time periods. To solve these two issues of space and power constrained microsatellites. Axelspace and Tokyo Tech have developed a downlink system. The system combines a broadband Ka-band transmitter and an active phased array antennas.

The Ka-band phased array radio developed in this research consists of a two-port antenna, amplifier, phase shifter, and active hybrid coupler. This enables electrical directivity control with low power consumption. The newly devised dynamic hybrid coupler circuit technology significantly reduces the power consumption of the phased array radio. Allowing faster and more real-time data communication than was previously possible.

The manufacturing of the radio IC is a CMOS process, which enables mass production at a low cost. Axelspace plans to install the successfully developed low-power phased array radio on our own Earth observation microsatellite. An in-orbit demonstration will be conducted within a few years. We will continue to further research and development. With the aim to shorten the time lag between ground capturing and data downloading as much as possible. As well as the acceleration of satellite data utilization.

The research results were supported by the JST Research Results Deployment Program A-STEP Industry-University Collaboration JPMJTR211D.