Doubling communication beams for small satellites

Japanese scientists have developed a 256-element Ka-band phased-array receiver that is designed to maximise energy efficiency and performance in small satellites. The introduction of a novel switch-type quadrature-hybrid in the CMOS chip of the receiver effectively doubles the number of controllable communication beams, paving the way for enhanced data throughput and broader satellite coverage.

As the world moves further towards seamless, global connectivity through satellite constellations, small satellites — weighing anywhere from 10 to 100 kg — are further enhancing the connectivity with their flexibility and scalability. But the application of small satellites often faces a significant challenge in their ability to accept communication beams, or electromagnetic waves.

In some waves, the electric field rotates in a spiral, and these waves are called circularly polarised beams. Based on the direction of the rotation, the beams can be either in right-hand circular polarisation (RHCP) or in left-hand circular polarisation (LHCP). Small satellites can only handle single polarisation beams, whereas bulkier satellites often require higher power to handle both polarised beams.

Now a team led by Associate Professor Atsushi Shirane at Tokyo Institute of Technology, which has been integrated into the Institute of Science Tokyo, has developed a Ka-band wireless chip for small satellite communication systems that can independently control the two circularly polarised beams — a feat that was unachievable with conventional technologies. Their research was carried out in collaboration with space venture company Axelspace and was presented at the 2025 International Solid-State Circuits Conference, held earlier this year in San Francisco.

“Conventional satellite communication receivers often struggle to handle both RHCP and LHCP beams independently,” Shirane explained. “To overcome this, we designed a switch-type quadrature-hybrid within a wireless chip that can pick up both left-hand and right-hand circularly polarised signals.”

A quadrature-hybrid is a special circuit that splits a signal into two parts, with one part delayed slightly to create a 90° phase difference. It breaks a circularly polarised signal into two straight signals and allows the chip to compare them. This helps to determine whether the signal was spinning left or right and therefore enables it to recognise both types of polarisation used in satellite communication.

The ability to independently steer both types of circularly polarised beams allows for greater communication flexibility, which is a critical requirement for satellite-based networks — especially as demand surges for broadband access in underserved and remote areas. Moreover, this innovation also doubled the number of controllable beams the satellite could handle, significantly improving the system’s capacity.

One notable benefit is that the chip has been fabricated using the widely adopted complementary metal-oxide-semiconductor (CMOS), which is a low-power, fast and compact technology used to build integrated circuits. This adds to the cost-effectiveness and scalability of the receiver, which is crucial for real-world deployments.

“Our receiver chip works in Ka-band frequency, known for its high-speed data transfer,” Shirane noted. “In fact, it’s the very same frequency band harnessed by cutting-edge satellite networks like SpaceX’s Starlink.”

To verify its performance, the receiver chip was tested within a prototype satellite-mounted communication device and was subjected to over-the-air measurements. This confirmed the chip’s performance in handling circular polarisation beams while maintaining the fundamental requirements for satellite communication systems.

The technology is expected to have a profound impact on satellite communication infrastructure, with the potential for further developments to enable broader high-speed connections — offering coverage across vast geographic areas that were previously unreachable. It could therefore mark a new chapter for satellite-based communication, making global communication more efficient, affordable and accessible.

Image caption: A CMOS chip with an integrated switch-type quadrature-hybrid and 4-array configuration, mounted on a 64-phase RX array to form a 256-element phased-array receiver.