With the ability amplifiers from Wolfspeed, the US House Pressure brings a “house fence” onto the market
On March 27, 2020, officials of the United States Space Force (USSF) announced the “initial operational readiness and acceptance of the Space Fence radar system”. The Space Fence is based on S-band radars (2 GHz to 4 GHz) and is a ground-based system that improves the USSF’s ability to track objects in both low-earth and geosynchronous orbits. Due to its network-centric alignment, it can be easily integrated into the existing room monitoring network.
Infographics about the need for space fence and its scope. Image courtesy Lockheed Martin
The purpose of the space fence is to track and catalog objects that are in the increasingly congested part of space that is just above the earth. This can include operational satellites, defunct satellites, debris from space collisions, and remnants of launch vehicles. These objects, which travel at speeds of up to 15,000 km / h, can destroy active satellites and even endanger the International Space Station.
The USSF nods to Wolfspeed’s amplifiers
Wolfspeed has provided Lockheed Martin with the high power gallium nitride (GaN) amplifiers (HPA) on which the project depends, said Steve Bruce, vice president of advanced systems for Lockheed Martin Mission Systems and Training.
“GaN HPAs offer significant advantages for active phased array radar systems like Space Fence, including higher power density, higher efficiency and significantly improved reliability over previous technologies,” he says.
Due to the classification of the project, we cannot know exactly which products are used in Wolfspeed’s extensive portfolio. However, Wolfspeed offers a product page on which some of its GaN-on-SiC (silicon carbide) components developed for satellite communication are presented.
One of Wolfspeed’s Ku-band GaN MMIC power amplifiers, the CMPA1D1E080F. The USSF has not specified which of Wolfspeed’s HPAs Space Fence will be used. Image courtesy of Wolfspeed
Without dealing with quantum mechanics, GaN and its sister technology SiC can process higher power, higher voltages and higher frequencies than silicon-based semiconductors. Compared to silicon, GaN semiconductors offer higher power densities, a higher degree of efficiency and the side effect of better tolerance to high operating temperatures.
Wolfspeed describes the advantages of GaN on both SiC and silicon substrates. The first advantage of GaN on SiC is that it has three times the thermal conductivity of GaN on silicon. The easier heat can be dissipated, the more resistant a device can be. Another benefit is fewer defects on each wafer for greater manufacturing efficiency. So it’s no secret why this technology could be an attractive option for the USSF when designing the space fence.
Digital beamforming for system flexibility
The Space Fence system architecture is based on digital beam shaping and offers enormous operational flexibility. This enables Space Fence to electronically construct a “microfence” to construct objects of high interest and to focus system resources specifically on this object.
A microfence built around a space object of high interest. Screenshot courtesy of Lockheed Martin
The original location will be the Kwajalein Atoll in the South Pacific. Each location has closely coordinated but separate receiving and transmitting antennas. Interchangeable transmit and receive lines (LRU) can be swapped out even if the site continues to function.
The Space Fence site on the Kwajalein Atoll. Image courtesy Lockheed Martin
Everything about the system emphasizes the minimal need for personnel, economic efficiency and low-maintenance operation. Looking ahead, the USSF says the system is fully scalable.
If you are into radar technology, how do GaN on silicon and GaN on silicon carbide stack up in your experience? Share your thoughts in the comments below.