Electronically Steerable Antennas – Essential Or Expensive Gimmick?

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One of the hottest topics in IFEC last year and a running theme as we move through 2020 is the Electronically Steered Antenna, or ESA. Numerous companies are pedaling hard to bring the first fully functioning ESA to market, eyeing airlines as key customers for this future technology. But why is the ESA such a good fit for aircraft, and is it the key to the future of inflight connectivity?

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Is the electronically steerable antenna a must-have for the future connected aircraft? Photo: Phasor

The benefits of the ESA for aircraft

One of the biggest issues with the current line-up of connectivity solutions is the negative consequences of sticking a radome on a plane. Aircraft manufacturers take painstaking care to build in optimum aerodynamics, in order to reduce fuel burn and create the most efficient airframe possible. Adding a bulky radome to the fuselage increases drag, and therefore fuel burn.

The solution to this is projected to be the Electronically Steerable Antenna (ESA). These small, lightweight and low profile antennas are capable of directing a narrow beam over a sector angle, giving coverage as good, if not better, than a sector antenna but all in a much smaller package.

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Mitsubishi’s 3cm tall active electronically steered array (AESA). Photo: Mitsubishi

For most companies developing this technology, the form of the ESA is a super low profile flat panel. In February this year, Mitsubishi unveiled an ESA less than 3cm tall which uses active tracking to boost satellite acquisition speeds.

However, some companies, such as Phasor, are working to bring to market an ESA that conforms to the shape of the fuselage. This characteristic would further reduce drag, whilst still providing powerful satellite tracking capabilities. Phasor’s ESA achieved ISO9001 certification last summer, and has been said to be on track to launch sometime in 2021.

Does it need to be electronically steerable though?

The big question remains whether the future aircraft antenna needs to be electronically steerable. Sure, a very low profile and negligible drag are key features, but that’s proven to be possible with standard Ka-band antennas anyhow.

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At the start of this year, ThinKom undertook an aerodynamic study of its Ka2517 antenna, with real-life testing on board some of the most popular regional jets in the US. The results indicated a near zero drag for the super thin radome, which bodes well for the future of non-steerable antenna too.

Thinkom Ka band antenna
ThinKom’s super thin Ka-band antenna has achieved near-zero drag in tests. Photo: ThinKom

Steerable antennas, in theory at least, should be an enabler for much higher speed and more reliable inflight WiFi. In tests, Gilat proved its ESA to achieve speeds of greater than 1GB over LEO satellites, and secured the accolade of completing the first ESA in flight operations at the end of last year.

However, along with the purported benefits of the ESA, there are some downsides too. ESA’s generate a lot of heat and draw down a great deal of power; two issues that are yet to be adequately solved. The antennas are also more complex than standard technology, which indicates there will be a price penalty to pay too.

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However, this last point is not confirmed yet, which brings us nicely on to the main issue with the ESA. Right now, there is not a single ESA licensed and available for sale for commercial aircraft. While lots is being done by a multitude of would-be suppliers, it’s still likely to be a year at least before anything is commercially available.

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Inmarsat’s GX10A and 10B will launch in 2022. Photo: Inmarsat

And all the while, satellite technology is improving immeasurably. Companies like SpaceX and OneWeb are establishing the building blocks of their LEO networks, and Inmarsat’s GX Aviation network is on the path to complete global coverage, with its highly elliptical orbit polar satellites set to launch in the next 18 months.

The real question is not whether the ESA will be the key to a better inflight WiFi experience, but whether it will arrive in time to be relevant at all. Superb satellite networks may well no longer require antennas to be steerable, so it remains to be seen if the ESA will ever find its niche.

What do you think? Let us know in the comments.

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