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https://fcc.report/FCC-ID/BCG-E8141A/6095651.pdf

L-Band is used exclusively for the satellite uplink. The power is significantly more than the majority of LTE/5G bands, but I see it's not the highest, actually that crown goes to GSM. Interesting. Seems like the much bigger reason that they don't need a large antenna is the other factor I mentioned, data rate, which is extremely low, while Starlink is targeting 2-4 Mbps. Plus there's the requirement to point the phone at the sky, while Starlink has stated that their service won't require that and should work from a pocket or inside a car. SpaceX has also specifically described the required satellite antennas as "really quite big".

Also, I'm not suggesting that the antenna is a "reflector dish" as you specified. It's a phased array, just much larger than the ones on previous Starlink satellites.



Oh, thank you for that link! I’ve been struggling to find exactly that FCC filing :)

I’m not surprised that GSM uses higher transmit power than Iridium/Globalstar actually – GSM phones were basically portable microwave ovens compared with modern mobile radio technologies.

But if you look at the table closely, the 5G C-band frequencies have even higher power outputs than Globalstar/L-band too! That's presumably because they are so wide, though (channels in band n77/n78 can be up to 100 MHz wide; compared to > 2W for 0.2 MHz wide channels for GSM, that's nothing).

Also, for bidirectional communications path losses are usually symmetric, and since satellites are usually severely power-limited compared to terrestrial base stations, blasting dozens of watts of transmit power from the mobile device wouldn't help with receiving the satellite's response.

> Also, I'm not suggesting that the antenna is a "reflector dish" as you specified.

Ah, I misunderstood then; I thought that's what you meant by "foldable antenna". I thought phased arrays are mostly solid-state (at least they are on comparable last-gen LEO satellites). But it makes sense for Starlink to do that; every bit of antenna aperture presumably helps when trying to talk to unmodified 4G mobile devices from space.




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