6 ms·

there is loss from the atmosphere when you beam it down

• pfdietz 3y ago
  Not much, typically.
  • MrOwnPut 3y ago
    I think 60% over a kilometer is the best efficiency thus far. What is the "typically" you are referencing?
    • pfdietz 3y ago
      Microwave beams are attenuated in heavy rain. Typically, the beam is not going through heavy rain. The 60% over a kilometer is not due to atmospheric absorption, it's due to losses at the transmitter and receiver (and beam spread exceeding the size of the receiver.) If microwaves lost 40% of their energy in a kilometer radar would have a hard time working. Millimeter waves are more strongly absorbed in clear air, so they are not as good for this use case. They may be good for powering aircraft.
• kybernetikos 3y ago
  yes, but you can concentrate the beam more than sunlight so that there's less atmosphere involved. You can also choose a beam technology (wavelength etc) based on it going through the atmosphere well, rather than having to stick with sunlight's properties.