Future global communication networks that also cover remote regions, withstand potential sources of interference, and can step in during disasters, must be able to reliably process high data rates. High-throughput satellites (HTS) in low Earth orbit (LEO) and/or geostationary orbit (GEO), which use the broadband Ka-, Q-, and W-frequency bands and follow strict modulation schemes, offer a promising option for implementing such networks. The hardware required for such communication systems, active antennas for electronic beam steering, relies on extremely efficient power amplifiers with high linearity. 

The compactness required for active antennas causes thermal problems with existing components. Researchers at the Fraunhofer Institute for Applied Solid State Physics IAF have therefore developed high electron mobility transistors (HEMTs) based on the wide bandgap compound semiconductor gallium nitride (GaN), which have a gate length of only 70 nm. The measured efficiency values demonstrate the great potential of this innovative technology for future applications in satellite communications.

Components for broadband satellite communication

“Thanks to their high linearity and efficiency, the GaN power amplifier HEMTs developed at Fraunhofer IAF enable more compact and energy-efficient communication systems for satellites. With our innovative technology, we are making an important contribution to the establishment and expansion of seamless and resilient global communication networks,” explains Dr. Philipp Döring, scientist in the Technology Department at Fraunhofer IAF and lead author of the research paper presenting the 70 nm GaN HEMTs.

Dr. Döring will present the paper “High efficiency and high linearity 70 nm GaN technology for future SatCom applications” on September 23 from 2:10 p.m. to 2:30 p.m. at the European Microwave Integrated Circuits Conference (EuMIC) in Utrecht, Netherlands. EuMIC is part of European Microwave Week (EuMW).

70 nm GaN transistors with record efficiency

The GaN HEMTs were developed, manufactured, and characterized in the in-house semiconductor line in the Epitaxy, Technology, and Microelectronics departments at Fraunhofer IAF. The GaN/AlGaN (aluminum gallium nitride) semiconductor material system was grown on semi-insulating 4-inch silicon carbide (SiC) substrates using metal organic chemical vapor deposition (MOCVD). Processing was carried out using electron beam lithography, among other methods. 
The researchers performed test measurements on individual transistors as well as directly on the wafer. In small-signal measurements, a cut-off frequency of fT = 122/95 GHz and a maximum frequency of fMAX more than 350 GHz were determined at VDS of 7/15 V. Load-pull measurements yielded a maximum power-added efficiency of 58.6% and a maximum output power of 2.46 W/mm at 38 GHz on 8×60 µm transistors.
To determine signal linearity, the researchers used a two-tone load pull method to test which of the 70 nm GaN HEMT meet the requirements currently specified by the European Space Agency (ESA) for satellite communications. Under the boundary condition of IMD3 ≥ 30 dBC, the technology achieved an efficiency of PAE = 54.4% and an output power of 1.01 W/mm. This is the highest efficiency value ever measured for a GaN technology at 30 GHz.

Technology development in the context of the Magellan and GANYDEM170 projects
The results were obtained as part of the Magellan and GANYDEM170 projects. Magellan is funded by ESA and aims to develop highly efficient millimeter-wave GaN high-power amplifiers for GEO and LEO active antenna applications. GANYDEM170 is funded as an IPCEI (Important Project of Common European Interest) by the German Federal Ministry for Economic Affairs and Energy (BMWE) and enables the realization of an industry-ready millimeter-wave GaN technology for metrology applications.

Fraunhofer IAF at EuMW 2025

At EuMW 2025, which will take place from September 21 to 26 in Utrecht, Netherlands, Fraunhofer IAF will present further research results from the field of GaN-based high-frequency electronics in addition to the findings of Dr. Philipp Döring. On the one hand, the institute will exhibit a wide selection of components, circuits, and modules at booth B071 at the trade fair. On the other hand, Patrick Umbach, Thomas Zieciak, Moïse Safari Mugisho, and Dr. Philipp Neininger will give presentations at EuMIC. In addition, the institute’s director, Dr. Patricie Merkert, will participate in the EuMIC Foundry Panel, where she will talk about monolithic and heterogeneous integration as well as chiplets.

Overview of all presentations by Fraunhofer IAF

EuMIC04-5 – Monday, September 22, 12:10–12:30
Patrick Umbach: Monolithic Integrated Broadband IF Balun and LO Amplifier

EuMIC06-4 – Monday, September 22, 14:50–15:10
Thomas Zieciak: A 200 mW, high-gain GaN-based D-Band Power Amplifier for 6G Communication Applications

EuMIC10 – Monday, September 22, 16:10–17:50
EuMIC Foundry Panel mit u. a. Dr. Patricie Merkert 

EuMIC11-5 – Tuesday, September 23, 9:50–10:10
Moïse Safari Mugisho: A V-Band (61–72 GHz) GaN HEMT High-Power Amplifier

EuMIC14-2 – Tuesday, September 23, 14:10–14:30
Dr. Philipp Döring: High efficiency and high linearity 70 nm GaN technology for future SatCom applications

EuMIC/EuMC03 – Halle 7 | 1-Minute Poster Pitch – Media Arena, 9:30–10:10
Dr. Philipp Neininger: An Integrated W-Band Dual-Polarization Receiver Front-End Featuring Ultra-Low Noise Figure
 

At the heart of this innovative ambition lies the development of a compact, flexible terminal known as the Mobility and Autonomy Market User Terminal, or MAMUT. This terminal will be capable of interfacing with multiple satellite networks, including Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and Geostationary (GEO) satellites. Innovatively designed with the user experience as a primary consideration, MAMUT operates under the premise of providing end-users with the autonomy to select their preferred satellite operator through an intuitive application interface. The aspiration is to empower customers, enabling them to optimize costs while maximizing flexibility in their connectivity options.

The project’s design caters to a diverse array of locations that often suffer from inadequate internet service, such as oil rigs, remote marine environments, or challenging terrains like mountains. The inherent challenges associated with ensuring robust connectivity in these areas are well recognized, making the development of MAMUT essential for improving internet access for various sectors that traditionally struggle in terms of connectivity. The innovative engineering behind MAMUT promises to drastically decrease the barriers faced in these remote locations, unlocking new potential for economic development and business operations.

Professor George Goussetis, a key figure at Heriot-Watt University, is spearheading the engineering of MAMUT’s satellite terminal antenna. Goussetis brings a wealth of expertise in microwave and antenna engineering to the table, aiming to create a solution that is not only effective but also economically viable. His insights have paved the way for an evolution in satellite technology that could lead to significant cost reductions in comparison to existing terminals on the market. This reduction will likely make satellite internet more accessible to a broader cross-section of the population.

In an interview, Professor Goussetis articulated his vision for the future of satellite connectivity, highlighting its opening of transformative opportunities across various sectors. For instance, industries like offshore operations, autonomous drone transportation, and emergency services stand to benefit significantly from improved internet access. He emphasizes the importance of future-proofing their designs, ensuring adaptability that will transcend current barriers and limitations.

Contributing to this extensive project is Dr. Samuel Rotenberg, a researcher from the School of Engineering and Physical Sciences at Heriot-Watt University. Dr. Rotenberg underscores the differences between MAMUT’s design principles and existing technologies, critiquing the prevalent focus on throughput performance metrics that hampers market growth. Many current terminal solutions are prohibitively large and power-inefficient, aspects that MAMUT aims to address through a more compact and energy-efficient design.

The innovative approach underlying the MAMUT project represents a significant leap toward creating a terminal that meets the demands of contemporary markets. This new terminal structure, compact and lightweight yet robust, is geared for a range of static and mobile applications, allowing potential expansion into budding sectors that require dependable internet capabilities. By making use of modern engineering methods, the team aims to create a multifunctional system that intertwines modularity with cost efficiency to cater to diverse customer needs.

The consortium, which includes leading firms such as Satellite and Space Consulting and Satraka Ltd, plays an integral role in solidifying the foundation of MAMUT. This collaboration not only combines expertise from various sectors but also maximizes the potential impact of the project. Through shared knowledge and resources, the group aims to elevate the standards of space technology applications within the UK and beyond.

The impact of this initiative reaches beyond simple connectivity; it promises to redefine entire industries. The UK Government’s investment in MAMUT, resulting from their £16 million funding allocation for the C-LEO programme, showcases a broader recognition of the potential in satellite-based technologies. By backing projects that propel innovation in satellite constellations, the UK Government aims to enhance the capabilities and efficiencies of its industries, ensuring that they are equipped to thrive in the competitive global landscape.

As the project enters its next stages, the focus will shift to the creation of a prototype terminal. Industry leaders will be engaged to discuss practical application scenarios, showcasing MAMUT’s advantages over existing technology. Such practical demonstrations will be crucial in fostering partnerships and securing further investments to drive the initiative forward.

Bethan Evans, the Chief Operating Officer of Excelerate Technology Ltd, expresses her enthusiasm about the project and its potential within the rapidly evolving space sector. The increase in satellite launches and projects nationally heralds an era of unprecedented opportunities in space connectivity. The funding secured for the MAMUT project is a critical enabler for realizing these advanced capabilities and ensuring that the UK maintains a pivotal role in pioneering the technological landscape.

Heriot-Watt University is also pursuing a comprehensive vision for the future, aiming to establish itself as a key hub for space technology innovation through initiatives like the proposed space tech cluster at its Edinburgh campus. This focus on bridging academic research with industry practice ensures that students are not only educated but also equipped to become leading innovators in the space industry.

The university’s leadership in space technology is further bolstered by its status as a leading institution for physics research and quantum communications. Alongside its advanced facilities, which include a powerful telescope that supports satellite research, Heriot-Watt is poised to make significant advancements in satellite connectivity. The collaborative spirit fostered in its research park with space-related businesses enhances the university’s capacity to implement real-world solutions derived from complex academic concepts.

Professor Gillian Murray, Deputy Principal for Business and Enterprise at Heriot-Watt University, emphasizes the university’s commitment to creating a thriving environment for innovation in space technology. With this pioneering work on MAMUT, Heriot-Watt illustrates its capability to navigate and transform the global landscape of scientific advancements and societal benefits. The synergy of research expertise and industry collaboration at the university underpins its ambition to ignite the next wave of technological evolution, cementing its legacy as a leader in space-based innovations that facilitate global connectivity.

Subject of Research: Connectivity in Low Earth Orbit
Article Title: Scientists at Heriot-Watt University Develop Groundbreaking Satellite Connectivity Solution
News Publication Date: October 2023
Web References: UK Space Agency’s Connectivity in Low Earth Orbit
References:
Image Credits: Heriot-Watt University

Keywords

Satellite connectivity, Low Earth Orbit, Heriot-Watt University, satellite technology, internet access, autonomy, MAMUT, UK Space Agency, innovation, research.