1
$\begingroup$

The images below are of actual OneWeb satellites or models. There are two disk-like appendages and an array of linear gizmos which may be an array antenna.

Is it possible to explain how these two types of structures work in some detail? Are the linear ones pointed at the ground? Do they steer electronically, and if so why is each row at a different fixed angle? Do the disks talk to adjacent satellites? Do they steer?

A model replica of a OneWeb satellite Regis Duvignau / Reuters

above: From the New York Times article OneWeb to Launch 34 Satellites as Astronomers Fear Radio Chatter "A model replica of a OneWeb satellite. Credit: Regis Duvignau / Reuters" below x2: from Aerospace Technology's OneWeb Satellite Constellation

click for full size:

enter image description here enter image description here

enter image description here

above: Cropped, rotated and sharped from www.ww01.net/en's Three ground stations will be built in China. What information does the “OneWeb” China Bank disclose?. below: From Caixin/com's U.K. Satellite Firm OneWeb Pushes Into China Market in Search of Scale

U.K. Satellite Firm OneWeb Pushes Into China Market in Search of Scale

$\endgroup$
3
  • 5
    $\begingroup$ It looks like a one-man-band getup with accordion and cymbals. media.gettyimages.com/photos/… $\endgroup$ – Organic Marble Feb 6 '20 at 23:02
  • 1
    $\begingroup$ Omg it does! Something seemed familliar; you've nailed it! $\endgroup$ – uhoh Feb 6 '20 at 23:03
  • 1
    $\begingroup$ English is not my first language, but I would prefer "how do" instead of "how to". But I may be wrong. $\endgroup$ – Uwe Feb 7 '20 at 16:26
3
$\begingroup$

I might be mistaken, but when I went through OneWeb architecture proposals, they were ditching the idea of Inter-Satellite-Links (ISLs), while it would make their satellites more expensive, heavier and generally more complex. But this can be an outdated information.

Answering other questions:

According to my colleague who have way more experience in Telecommunication, those are indeed phased arrays and they would look down to Earth. The sole purpose of them placed at certain fixed angles is to reduce the impact of the gain loss due to the electronic steering. So consider it as a 'mechanical' pre-steering. For instance, some Satcom-on-the-move terminals are also utilize the mechanical pre-steering, because electronic steering is limited and will provide poor results for very steep angles.

EDIT: Addressing the Uhoh's comment: at the moment, I was able to find single source that mentions the combination of mechanical and electrical beam steering for the Satcom-on-the-move terminal. Link is here. See section 4.7.4.2 and figure 4.23 (B). However, there are plenty of mechanical vs electrical tilt discussions, which are rather related to the terrestrial comms. Example here. See the 'what is Tilt?' section. It is also mentioned there that combination of both mechanical and electrical tilting at the same time might help you to satisfy your goals for a smaller budget.

$\endgroup$
5
  • 1
    $\begingroup$ I will ask my colleague, if he have some examples in mind. ISLs are Inter-Satellite-Links, I will edit it in my answer. $\endgroup$ – prop-a-gator Feb 7 '20 at 10:38
  • $\begingroup$ that's great, thanks! $\endgroup$ – uhoh Feb 7 '20 at 14:03
  • 1
    $\begingroup$ I'd like to click accept on your answer; is there any chance you can find at least a minimal supporting source or citation that mentions that these are phased arrays? Thanks! $\endgroup$ – uhoh Feb 23 '20 at 6:20
  • 1
    $\begingroup$ I believe that OneWeb keeps their antenna design as a commercial secret, so there is no way to we can 100% prove that those are phased arrays. However, considering their goal to serve as many users as possible, one may speculate that they would try to maximize the amount of connections per single satellite, hence the throughput. And besides, there are no other visible elements on the satellite that can serve that purpose (I don't believe those two horns are the main comms payload). $\endgroup$ – prop-a-gator Feb 24 '20 at 9:13
  • 1
    $\begingroup$ Now after I checked the Aerospace-Technology's article, it is stated there that: 'Other payloads onboard include two TTC omni antennas, two Ku-band antennas, two Ka-band antennas, and a three-axis stabiliser.' From that, I assume that those two horn/dishes are also part of comms payload (as for TTC only omni antennas are going to be used). $\endgroup$ – prop-a-gator Feb 24 '20 at 10:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.