Advertisement

Starlink

Update May 2022: we've added a second video that continues the teardown on the exact same "Dishy" unit!

New for April 2022: we are by no means experts on Starlink, and we gladly offer space on Microwaves101 for anyone that wants to comment on or correct what we have put together.  This will be a multi-month project, we are just getting started...

Starlink is SpaceX's satcom service that uses thousands of low-cost (maybe $500K) low-earth orbit (LEO) small satellites to deliver data with less than half the latency of geo-stationary satellites, at much higher capacity. Starlink can bring high-speed internet to rural areas that have always been underserved. Yeah!  What's a better tribute to such a game-changing development, than to figure out how it works?

As of April 2022, a Starlink user terminal costs the consumer $600 (while rumored to cost more than double that to manufacture), with a monthly charge of $110 (after a 10% price increase this year). Depending on who does the math, Starlink could be profitable in a few short years, or possibly never.  We may never know the financial picture, because SpaceX is a private company. A recent solar storm caused 40 brand-new Starlink satellites to decelerate to the point where they will soon crash and burn... whoops, there goes another $100M if you include the launch cost...and lately, Russia is jamming Starlink in support of Putin's war crime in Ukraine, which will hurt the bottom line as no one is going to pay for a service that is off-line.  You can imagine that the US government might consider Starlink as a military asset (which could make jamming at an act of war), as it has funded the system $885 million to assist rural broadband (good cover story, bro), and purchasing and shipping 1500 user terminals to Ukraine.

For all of his idiosyncrasies and oafish behavior, Elon Musk is the Henry Ford of our time. While working up to delivering Ford's 20-millionth automobile, and needing to up the automobile game during the great recession, Henry Ford secretly developed a single-casting V8 motor, temporarily closed the majority of the Ford production line while retooling it, then offered the1932 Ford Model A V8 for $460. That car could achieve 75 MPH and was an instant hit, even bank robbers were huge fans... Watch the story of the Ford V8 when you have an hour to spare, it is something engineers should be proud of. The Ford company did not go public until 1956, eight years after the founder died.  But we digress....

Musk offers cryptic information on Starlink on this website:

https://www.elonx.net/category/spacex/

Dishy

Here we will discuss the Starlink ground terminal design, and take a shortcut by embedding some videos. The best way to evaluate such a design is to tear it apart.  First you will have to pony up $600. BTW, Dishy McFlatface is SpaceX's internal nickname for the Starlink user terminal.

Dishy is shaped like a flat dish (as opposed to parabolic dishes for television/satellite systems like Dish Network), and has a motor that coarsely adjusts it in elevation.  It is a two-dimensional phased array, so it can electronically steer in both azimuth and elevation. The phased array follows the LEO satellite across the sky, and seamlessly moves the link from one satellite to another as they enter and exit the field of view.

Ken Keiter Dishy teardown video

Ken's YouTube channel was the first to show a Starlink "Dishy" teardown in 2020. Ken admits he is not really an RF guy, and focuses on physical details of the system such as dimensions and material stack-ups. Here are some things you will learn by watching this video:

  • It is NOT designed to be taken apart

  • The antenna elements are stacked patch microstrip radiator with round elements

  • The array is on a hexagonal lattice

  • It has built-in GPS, presumably to set up the elevation angle

  • The terminal consumes 100W power, directly from ethernet cable

  • There is a single buried SMA connection, presumably used for calibration

  • Thermal "blobs" pass heat from the array to the aluminum back plate

  • It measures 50 cm wide (19.75 inches) It's huge!

  • The downlink frequency is 37.5 to 42.5 GHz (Ken got this way wrong, more on this later)

  • The uplink frequency is either 47.2 to 50.2 GHz  or 50.4 to 52.4 GHz (wrong again...)

  •  

Ken Keiter Dishy teardown video

The Signal Path Dishy video

Update May 2022: Shahriar Shahramian's The Signal Path YouTube channel has more than five million views for a reason.  He is an RF subject matter expert!  Ken Keiter, who filmed the first Dishy teardown, definitely follows The Signal Path, he actually sent his torn-up broke-ass Dishy to Shahriar for further analysis.

Here's a video from The Signal Path, continuing the Dishy teardown, including radiographic analysis of teh circuit card. Shahriar sure has a lot of resources in his laboratory!

Starlink Dish Phased Array Design, Architecture & RF In-depth Analysis

In his video, Shahriar Shahramian makes the following points (stuff in parenthesis are comments we made):

  • The array uses a stacked patch radiator (usually done for improved bandwidth and scanning performance)

  • He goes back forth about whether the array is circularly polarized, ur provides separate horizonal and vertical polarizations

  • The array has 1200 elements (estimated)

  • The copper patches are unplated (or perhaps coated with something to prevent oxidation)

  • Up- and down-link frequencies are around 14 and 10 GHz (Specifically, according to this web site, 14-14.5GHz is the uplink band, and 10.7-12.7 GHz is the downlink band.)

  • The array features tapered amplitude to reduce sidelobes

  • A bandgap structure surrounds the elements to mitigate unwanted propagation between elements

  • Shahriar drops a W-band array on top so you can see how phased arrays scale.  It's tiny!

  • The FEM (front-end module) and custom chips made by ST Microelectronics (silicon, maybe SiGe BiCMOS or straight CMOS... maybe even SOI.)

  • A single phase-lock loop (PLL) circuit near the center of the array feeds all of the RFICs to keep everything synchronized.

  • Dishy possibly uses hybrid analog/digital beamforming.  (We think that the front end chips probably use RF phase shifters and maybe the subarray beams are combined digitally.)

  • There are possibly two beamformers, so that the array can point in two directions at once. (That would be handy when moving the connection from one LEO satellite to the next.)

  • We wish he had zoomed in more when discussing the chips

  • One FEM serves two elements. (The front-end chips could just be amplifiers)

One small nit… at 16:30, Shahriar mixes up the word “fiduciary” for “fiducial”. Fiduciary is someone that handles your money, fiducial is an alignment mark. Overall, it is a five-start effort, keep up the good work!  Be sure to read the comments on Shahriars' video, looks like a lot of industry experts weighed in on the design.

If you want to take a deeper dive into Starlink, you might want to peruse some of their patents and patent applications.  This website has a nice compilation of recent SpaceX patent works.

If you find this subject interesting and have any thoughts on the Dishy design, send an email our way and we willtry to include them on this page.
 

Author : Unknown Editor

Advertisement