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Amazon's reply to SpaceX Starlink delivers 400 Mbit / s within the prototype part

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Amazon's competitor to SpaceX Starlink is in the prototype development phase. The company announced yesterday that it has "completed the first antenna development for our cost-effective customer terminal".

According to Amazon, the "Ka-band phased array antenna is based on a new architecture that can deliver high-speed, low-latency broadband in a form factor that is smaller and lighter than traditional antenna designs," and the "prototype is already delivering speeds up to 400 Mbit / s. "According to Amazon, the performance will be better in future versions.

Amazon received Federal Communications Commission approval in July to launch 3,236 low-earth orbital satellites. The company plans to invest over $ 10 billion in its satellite broadband division, which it calls Project Kuiper.

Ka-band antennas

To reduce production costs, Amazon needs to "reduce the size, weight and complexity of the antenna". However, this is difficult with Ka-band devices, which "require a greater physical separation between the transmitting and receiving antennas to cover their wide frequency range," said Amazon. "For this reason, conventional Ka-band antennas place the transmitting antenna and the receiving antenna next to each other, which requires a larger surface area and increases production costs."

Amazon said its solution is to "use tiny antenna element structures to overlay each other. This has never been achieved in Ka-band … Our design uses a combination of digital and analog components to create Ka-band beams electronically to steer satellites overhead. "Using this method, Amazon was able to create a" phased array antenna with an aperture and a diameter of 12 inches that is three times smaller and proportionally lighter than traditional antenna designs, "the company said.

A Project Kuiper prototype antenna in an Amazon laboratory. "Src =" https://cdn.arstechnica.net/wp-content/uploads/2020/12/amazon-kuiper-lab-980x553.jpg "width =" 980 "height = 553Enlarge /. A Project Kuiper prototype antenna in an Amazon laboratory.

According to FCC filings, Amazon's satellite plan sees the use of frequencies from 17.7 to 18.6 GHz and 18.8 to 20.2 GHz for space-to-earth communications and 27.5 to 30.0 GHz for transmissions from earth to space.

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The antenna passed all tests

Amazon tested the prototype with a geostationary satellite, but will use near-earth satellites when it finally offers broadband to customers.

"Amazon engineers tested the antenna in multiple environments to ensure it met customer standards for speed and performance," the company said. "The antenna has passed all relevant tests for speed and latency. It offers a maximum throughput of up to 400 Mbit / s and transmits 4K quality video from a geostationary (GEO) satellite stationed at an altitude of around 50 Times farther from Earth than Project Kuiper satellites are used. "

An Amazon employee working on the prototype antenna. "Src =" https://cdn.arstechnica.net/wp-content/uploads/2020/12/amazon-employee-kuiper-antenna.jpg "width =" 2633 "height = 1478

An Amazon employee working on the prototype antenna.

The antenna will be designed and tested at Amazon's new research and development facility in Redmond, Washington. Amazon is hiring numerous open positions at Project Kuiper.

Amazon also published an interview with Nima Mahanfar, Senior Manager of Antenna Development for Project Kuiper. He provided more information on how Amazon combined transmit and receive antennas:

The decisive advance was to combine phased array antennas for transmitting and receiving in one aperture. This can be done in other frequency bands, but Project Kuiper plans to operate in the Ka-band, which has transmit and receive frequencies that are much further apart. This makes it difficult, almost impossible, to combine transmission and reception in one aperture. Phased arrays are a class of radiation systems in which multiple antennas – there could be two, there could be thousands – are placed on the same aperture and produce a focused beam of radio waves. The distance between the antennas – or the relationship between these antennas – is determined by frequency. If the frequencies are close together like Ku-band, you can combine the transmit and receive functions into one and it will work. When the frequencies are far apart, as in the Ka-band, it is much more difficult to use the same grating for both. This has never been done before.

Our design includes hundreds of antennas in each aperture, with receiving antennas operating at 18 to 20 gigahertz (GHz) and transmitting antennas operating at 28 to 30 GHz. Our breakthrough came from realizing that we can get to a single grid by looking at each antenna element individually – which helps reduce the size and cost of our entire terminal.

Despite this complexity, the antenna must be simple enough "to be mass-produced by major circuit board manufacturers so that we can leverage economies of scale and produce millions at low cost," Mahanfar said.

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Amazon prioritizes download speeds

Amazon had to balance the compromises between sending and receiving functions. Mahanfar said, "We are always on the side of improving reception performance" to ensure good download speeds. "On the transmit side, you can always bump up the transmit power a little if you hit the performance," he added.

Going forward, Mahanfar believes Amazon can make phased array technology more affordable "by developing new technologies and architectures that could be fundamentally different from today's approach."

He also briefly discussed the phased array technology Amazon is developing for the satellites it will launch into space. "It's difficult to solve energy problems in space, and it's even more difficult to get the heat away from that energy," he said. "There is no air to cool it. A low-power system that can provide many gigabytes of service to customers is key. How can we reduce the power consumption of these space-based phased arrays? This is one of the other major challenges." Anyone who uses phased array antennas in low earth orbit. "

Amazon has not provided any updates as to when Kuiper will be ready for customers. Under the FCC rules, Amazon has six years to start and operate 50 percent of its licensed satellites. The deadline ends on July 30, 2026. Amazon would have to launch the rest of the licensed satellites by July 30, 2029. Amazon had previously announced it would offer broadband to customers "as soon as the first 578 satellites are launched".

SpaceX Starlink satellites are already delivering broadband to beta customers. The company promises initial speeds of 50 Mbit / s to 150 Mbit / s and a latency of 20 ms to 40 ms. SpaceX has announced plans to make significant performance improvements through the summer of 2021. Details and pictures of the SpaceX user terminal "Dishy McFlatface" can be found in our previous coverage.

Amazon is also behind OneWeb, which recently ended bankruptcy and plans satellite launches this month and "in 2021 and 2022". OneWeb yesterday announced a contract under which Hughes Network Systems, a traditional satellite provider, will "produce the gateway electronics for the OneWeb system as well as the core module used in each user terminal."

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Steven Gregory