News: Microelectronics
19 September 2024
Fraunhofer IAF low-noise amplifiers used aboard ESA’s Arctic Weather Satellite
At EuMW 2024 in Paris, the Freiburg-based institute is presenting exhibits of the amplifiers installed in the AWS as well as other high-frequency electronics from the application areas of satellite communications, mobile communications and low-temperature measurement technology 24–26 September).
On 16 August, the European Space Agency (ESA) launched the Arctic Weather Satellite (AWS) to a polar low-Earth orbit 600km above the Earth, with the aim of collecting accurate weather data of the Arctic for the first time and improving forecasts and climate observations worldwide.
The AWS uses a microwave radiometer that contains four low-noise amplifiers (LNAs) from Fraunhofer Institute for Applied Solid State Physics IAF of Freiburg, Germany. They are essential components of the passive microwave radiometer with which the AWS measures temperature and humidity in the Arctic more precisely than ever before. This should contribute to a better understanding of both the Arctic and the climate change that is particularly visible in it.
“The more powerful a low-noise amplifier is, the more accurately and reliably a system can collect data. They play a major role in satellite-based Earth observation, as the microwave radiation that reaches the satellite radiometer is very weak,” explains Dr Fabian Thome, deputy head of Fraunhofer IAF’s High Frequency Electronics business unit. “It is a great confirmation and motivation that we are contributing to better research into the Arctic and its effects on the global climate.”
LNAs for frequency ranges around 54, 89 and 170GHz
The AWS microwave radiometer consists of a rotating antenna that picks up the natural microwave radiation emitted by the Earth’s surface and transmits it to four feedhorns and four receivers. The antenna and receiver each belong to one of four groups comprising a total of 19 channels, which together cover a frequency spectrum of 50–325GHz: Eight channels with frequencies from 50GHz to 58GHz measure temperature, one channel at 89GHz detects clouds, another at 165.5GHz both clouds and humidity, five channels between 176GHz and 182GHz are only responsible for humidity, while finally there are four channels at 325GHz plus/minus 1.2GHz to 6.6GHz measure humidity and also detect clouds. The radiometer is hence able to create high-resolution vertical humidity and temperature profiles under all weather conditions.
Fraunhofer IAF has provided a total of four LNAs for three of the four channel groups: one module for the frequency range around 54GHz, two identical modules for 89GHz (connected in series for greater overall amplification), and one module for the 170GHz range. The researchers have enhanced proven technologies based on indium gallium arsenide (InGaAs) and realized metamorphic high-electron-mobility transistors (mHEMTs) for monolithic microwave integrated circuits (MMICs).
InGaAs mHEMT technology for MMICs
In tests, the LNA for the frequency range around 54GHz achieved a noise figure of 1.0–1.2dB with a gain of 31–28dB, significantly improving the state of the art. With noise figures of 1.9–2.3dB at 23–25dB gain (89GHz) and 3.3–4.1dB at 25–30dB gain, the other AWS LNAs are exactly in the range of the existing state of the art (John et al, ‘Low-Noise Amplifiers for the Arctic Weather Satellite’, 2023 53rd European Microwave Conference (EuMC)).
Close-up of the 89GHz LNA MMIC integrated into the respective AWS microwave radiometer LNA module (© Fraunhofer IAF).
In developing the modules, the researchers worked closely with the direct client ACC Omnisys (AAC Clyde Space) of Sweden, which built the radiometer system for OHB Sweden and ESA. Fraunhofer IAF was able to use its research infrastructure and expertise along the entire value chain in the development and production of the modules: Teams from microelectronics, epitaxy, technology and precision mechanics worked together and carried out all the key steps from circuit design to material growth, processing and measurement as well as process technology, separation, assembly technology through to module construction and integration until the LNA modules were ready for use. An initial qualification of the modules for use in space also took place at the institute before the hardware was handed over for receiver integration.
AWS and EPS-Sterna: New Space for more precise weather forecasts, nowcasting and climate monitoring
The AWS mission is to collect more precise weather data in the Arctic for the first time, which will enable short-term forecasts for the polar region, including nowcasting (for the next few hours). As the Arctic has a strong influence on global weather, the data also enables better global weather forecasts. This also applies to the climate, since climate change is progressing faster in the Arctic than in other regions of the world. At the same time, changes in the Arctic have an impact on the global climate due to feedback effects.
If the AWS mission is successful, ESA plans to launch a global constellation of identical small satellites into space to enable more precise and shorter-term weather forecasts and climate observations on a global scale. The plan for this EUMETSAT Polar System — Sterna (EPS-Sterna) is to have six satellites in three different orbits at the same time to collect long-term weather data from the polar regions. The satellite set will be renewed three times, so that a total of 18 satellites will be used during the time of the mission. Two satellites are planned as replacements. The first of six EPS-Sterna satellites is due to be launched in 2029.
With this project, ESA is pursuing the New Space approach for the first time. New Space is characterized by projects being carried out in the shortest possible time with significantly fewer resources. In the case of AWS, whose total mass is only 150kg, only three years passed from project start to rocket launch, during which a fraction of the cost was incurred compared with previous projects. Further advantages of New Space are the greater resilience of constellations — the failure of a satellite in the network can be compensated for or replaced quickly and cheaply — and the flexibility of missions, which can be extended or shortened if necessary, without consuming large amounts of resources.
Fraunhofer IAF at EuMW
In booth 202K at European Microwave Week (EuMW 2024) in Paris, France (24–26 September), Fraunhofer IAF is presenting exhibits of the LNA modules installed in the AWS radiometer as well as other high-frequency electronics from the application areas of satellite communications, mobile communications or low-temperature measurement technology.
Researchers are also represented in the conference program with the following topics:
- 22 September (8:30–12:20, WS09 EuMC, Room 725–726): ‘THz circuit and front-end developments based on InGaAs-channel mHEMT devices’ by Dr Laurenz John;
- 23 September (8:30am, EuMIC03, Room E04): ‘High-Gain 664GHz Low-Noise Amplifier Modules Based on Advanced InGaAs HEMT Technologies’ by Dr Axel Tessmann;
- 23 September (16:50, EuMIC14-3, Room E02): ‘mm-Wave GaN Varactors and E-/W-Band Phase Shifter’ by Dr Philipp Neininger.
On 25 September (12–3pm), students and young professionals from the field of microwave technology can also get to know Fraunhofer IAF at the Young Professionals’ Career Event in Hall 7.3 of the Paris Expo Porte de Versailles. Participation is free. The accompanying Career Party takes place from 7pm at Chalet du Lac (avenue Anna Politovskaïa, 75012 Paris). Tickets are available at the afternoon event.
Fraunhofer IAF launches BEACON project as part of ESA’s ARTES program
https://ieeexplore.ieee.org/document/10290663
www.esa.int/Applications/Observing_the_Earth/Meteorological_missions/Arctic_Weather_Satellite
