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I wonder if it would be practical to install upwards facing antennas on cell tower and then have a tracking dish on planes track these to cut out the satellite

I wonder if it would be practical to install upwards facing antennas on cell tower and then have a tracking dish on planes track these to cut out the satellite when over (populated) ground. If a line-of-sight microwave link could be established, it should be possible to have high-bandwidth low-latency connectivity in the air. What is the effective beamwidth of a microwave antenna that needs to maintain a 50-100km link? Would the ground antennas need to be tracking as well?

toomuchtodo 14y ago
Tracking aircraft is not practical unless you're going to use a phased array, and the problem you'll run into then is how large the cells are when you're pointing towards the sky, reducing spectrum separation.
- mseebach 14y ago
  Why is tracking aircraft impractical? In university I was involved in building an antenna that would track a LEO satellite (a bit crudely, though), with a pass taking about 15 minutes - that's pretty similar to a pass by a full-altitude aircraft. The main impracticality I can see is that you'll need an antenna pr. aircraft in range.
  - hga 14y ago
    If you want to track a number of aircraft, and not require an antenna/dish per each or have resultant mechanical breakdowns, phased array antennas are the best solution.
    - toomuchtodo 14y ago
      Thanks for responding.
jof 14y ago
This is _exactly_ what Aircell does in the US. I'm not sure what spectra they're using, but the bandwidth would likely be quite variable, as planes with non-directional antennas will interact with one another over wide areas. Weather could also play a part, depending on the frequency.
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state_machine 14y ago
This (Air-to-Ground) is what Gogo does, using EV-DO Rev A. http://en.wikipedia.org/wiki/Gogo_Inflight_Internet http://en.wikipedia.org/wiki/Gogo_Inflight_Internet Last couple flights I've usually seen latency between 300ms and 3500ms, 8-10% packet loss. They also seem to use Squid proxy, which doesn't understand WebSockets.

toomuchtodo 14y ago

Tracking aircraft is not practical unless you're going to use a phased array, and the problem you'll run into then is how large the cells are when you're pointing towards the sky, reducing spectrum separation.

mseebach 14y ago
Why is tracking aircraft impractical? In university I was involved in building an antenna that would track a LEO satellite (a bit crudely, though), with a pass taking about 15 minutes - that's pretty similar to a pass by a full-altitude aircraft. The main impracticality I can see is that you'll need an antenna pr. aircraft in range.
- hga 14y ago
  If you want to track a number of aircraft, and not require an antenna/dish per each or have resultant mechanical breakdowns, phased array antennas are the best solution.
  - toomuchtodo 14y ago
    Thanks for responding.

jof 14y ago

This is _exactly_ what Aircell does in the US. I'm not sure what spectra they're using, but the bandwidth would likely be quite variable, as planes with non-directional antennas will interact with one another over wide areas. Weather could also play a part, depending on the frequency.

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state_machine 14y ago

This (Air-to-Ground) is what Gogo does, using EV-DO Rev A. http://en.wikipedia.org/wiki/Gogo_Inflight_Internet http://en.wikipedia.org/wiki/Gogo_Inflight_Internet Last couple flights I've usually seen latency between 300ms and 3500ms, 8-10% packet loss. They also seem to use Squid proxy, which doesn't understand WebSockets.