New answers tagged radio
The problem is how waves interact with matter. Thickness of walls is not to be taken into account, since basically a wall is (partially) not metallic, therefore attenuates e.m. waves but doesn't reflect them. You cannot generalize on the material too, because air is in fact not very different from concrete. What changes? Epsilon and Mu of the medium in which ...
Bandwidth, and a more specifically amount of information you can send within it is crucial. Satellites are used for video transmission (DVB-T2), audio communication (Inmarsat), data communication (Internet link) and all of this within one hardware box. Jamming. This is the crucial issue, imagine 1000 people communicating with each other in the same channel, ...
This technique is only good for frequencies below about 30MHz, and tend to be omnidirectional (depending on antenna). This limits the amount of information that can be encoded and transmitted between specific Tx/Rx pairs. Satellites use tightly focused beams in the tens of GHz, providing far higher bandwidth and more discrimination between data paths.
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