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Next-Gen Antennas for Next-Gen Satellites

There are a plethora of research and development efforts under way right now among in-flight connectivity antenna makers. The majority of them are moving toward lower-profile designs, with little-to-no moving parts in a variety of architectures and performance categories including phased array, multi-beam, and multi-constellation. With future low earth orbit (LEO) constellations providing so much potential to disrupt the economics around in-flight connectivity for airlines, most of the antenna suppliers interviewed are keeping their designs as open and flexible as possible.

A great example of next generation antennas in development are those being worked on in partnership by Astronics Aerosat and Phasor. Astronics AeroSat is acting as the integrator for Phasor’s phased-array technology into an agile aviation antenna solution that will operate seamlessly with Geostationary Earth Orbit (GEO) and non-geosynchronous satellites, such as LEO wideband constellations currently in development. The new antenna will feature dual-beam technology, or the ability to simultaneously send and receive signals.

“Our antenna has the ability to do both transmit and receive from a single antenna array, instead of separate antenna arrays,” Astronics AeroSat President Matthew Harrah told Avionics International. “This includes dual beam receivers allowing for full ‘make before break’ capability and a single transmit. This is critical for support of future non-geostationary (ex. LEO) satellite constellation operation. This results in a smaller footprint and lower weight relative to other solutions.”

Astronics AeroSat recently received European Aviation Safety Agency (EASA) certification of its next generation SATCOM connectivity system. Astronics AeroSat

A key section of the commercial aviation market that the Astronics-Phasor partnership will focus on is the smaller regional airframes, such as the Airbus A220, and some of the Embraer first and second generation regional aircraft. Those airframes provide antenna suppliers with a smaller fuselage radius area to work with.

Harrah said to address that end of the market, the partnership is developing a mid-sized antenna measuring 78-by-48 inches in length and width, and 3.5 inches in height above the fuselage. The two companies are also developing a smaller antenna for LEO-only satellite networks, with applications ranging from turboprop to twin aisle aircraft.

“The modular Phasor antenna array architecture is a real strength in this regard as we can provide the right size of array for the aircraft platform and/or user bandwidth requirements,” Harrah said, adding that he expects to perform the first flight with their new antenna by mid-2021, with the first deliveries to follow in 2022.

In their development process, Astronics and Phasor are also adhering to ARINC 791 and 792 mounting compliance standards. Both standards are developed by the ARINC Industry Activities Ku/Ka-band satellite subcommittee, which consists of airlines, airframe manufacturers and antenna suppliers. The committee standardizes the satellite communication (satcom) equipment, installation, and necessary interfaces to aircraft systems that enables satellite-based connectivity on aircraft.

During its upcoming September meeting hosted by Boeing in Seattle, the committee will be focused on finalizing a second supplement to the ARINC 791 specification, including new electrical interfaces and functional equipment descriptions that will address cyber security concerns and examine the management information base associated with 791.

There is also an update coming to ARINC 792, with a new antenna and modem manager form factor as well as accommodation for dissimilar interchangeable modems capable of supporting two or more networks. The committee is also updating 792 with a new modem-to-antenna interface and thermal management for antenna equipment as well.

LEOs in Focus

One company with a strong focus on the potential promised by LEO satellite constellations is Kymeta, which is currently developing a flat panel antenna that promises to be a disruptor for the commercial aviation market. The company was founded in 2012 and is currently developing its u7 flat panel Ku-band antenna, with plans to develop a Ka-band version in the future, according to Kenny Kirchoff, director of government airborne solutions at Kymeta.

“Kymeta is developing a full, integrated solution that is cost effective compared to other flat panel antenna technologies, low weight, low profile, and low power that can be easily integrated into the aircraft,” Kirchoff said. “Our next generation product will also be LEO-compatible, which would mean early adopters would not be penalized when LEO constellations are fully operational.”

Kymeta’s flat panel Mtenna design. Kymeta

Kymeta’s goal is to develop a metamaterial electronically steerable flat panel antenna with no moving parts. According to a June 2019 white paper published by Kymeta about the antenna, the materials they are using are essential to ensuring consistent performance on airplanes and other forms of mobility.

Whether or not the potential disruptive capabilities promised by Kymeta’s flat panel design remains to be seen, when Kymeta gets its antenna on an actual in-service passenger carrying aircraft and demonstrates its ability to maintain connectivity on an actual flight. However, one of the main advantages to active phased arrays, noted by the company’s June 2019 white paper, is that the flat panel antenna being developed by Kymeta has a form factor with just one single aperture for transmitting and receiving signals, compared to active phased arrays, which today require two separate apertures.

“There are plans to develop a Ka-band product in future, but right now Kymeta is focused on releasing our next generation product which is the culmination of 7 years of research and 2 years of field experience,” Kirchoff said.

Elsewhere in the world of antenna design and development, ThinKom makes one of the most widely used antennas across commercial aviation, with its current phased array antenna already in use by 15 different airlines across more than 1,300 in-service aircraft globally.

ThinKom Chief Technology Officer Bill Milroy said as the company looks toward its future antenna technology, their approach is to be as compatible with as many different satellite bands and constellations as possible. Milroy also understands the challenging decision-making process airlines must undergo when considering upgrading their aircraft fleet’s in-flight connectivity.

A side profile view of ThinKom’s Gogo 2Ku antenna.ThinKom

While antenna-makers and in-flight connectivity service providers are constantly innovating, the airplane that their technology will be installed on has an average in-service lifespan of 15 to 20 years. Getting stuck with outdated technology can become a problem if an airline’s competitor equips with a more robust solution.

“If you’re an airline today, it must be a daunting question to say what if I make [a] mistake? What if I stay with a GEO system, be it Ku or Ka-band and go with that? Or what if I dedicate myself now to a LEO-based system, and take some of those attributes, and go with that? We think it’s super important to be a hybrid-capable system,” Milroy said. “We think it’s important to bring a no compromise GEO capability, and not to have to drop that back because you may end up relying on the GEOs more than you thought. But at the same time bringing the beam agility and all of the specialty capabilities that are required to work with the LEO and MEO satellites.”

OneWeb satellites, a joint venture of OneWeb and Airbus, has almost every antenna manufacturer wanting to support future LEO networks. The venture opened a satellite production facility on Florida’s Space Coast in July. Its goal is to build out a satellite network initially numbering 648 total satellites.

On August 6, 2019, the company took an important step toward leveraging that future network for the aviation industry by appointing former Inmarsat executive Ben Griffin as its new vice president of commercial aviation. Griffin told Avionics International that his company is focusing on leaving antenna development to the experts and is currently in discussions with several antenna suppliers that will be announced “in due course.”

ThinKom Ka-band phased-array antenna mounted on Proteus aircraft. ThinKom

“LEO benefits from being only 750 miles altitude, as opposed to 22,000 miles in GEO,” Griffin said. “This equates to significantly lower latency which in turn makes for a far richer passenger experience - truly comparable with being on the ground. It’s our own network that we fully own and control, without the need for any third parties nor are we jostling for orbital space in the GEO network.”

The first successful launch of OneWeb’s satellites came in February, which was followed by a July 2019 satellite capacity demonstration where their satellites proved able to deliver 1080p streaming video with a latency of less than 40 milliseconds and speeds of over 400 megabits per second. However, that test and current ongoing testing of their initially launched satellites are occurring in a lab environment.

It remains to be seen how those same satellites will perform when OneWeb begins live testing on aircraft.

“Once we have achieved certification, which we hope to gain by the fourth quarter of next year, we can live test on aircraft with various terminals, which are already under development,” Griffin said. “We aim to be offering full demos in early 2021.”