g86
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flatulent said:This law, like many others, is based on approximations and assumptions that are valid for the usual cases of practical situations. Taking them to limits that make these assumptions and approximations false will produce false calculated results.
One example of this would be to use such a large gain at each end of your imiganary link that the formula predicts more received power than the transmitter output.
flatulent said:You are not. In the optical region it is possible for all of the transmitted energy to be focused (like a laser beam) so that it strikes a photodetector.
The practical problem in your microwave case is the construction of such large diameter antennas and the tolerances of the surfaces. I know of cases where there was consideration of raising the operating frequency of a RADAR in the hopes of getting better angle resolution. The surface of the antenna reflector was so wobbly that when they connected higher frequency electronics to it the resolution declined because of the beam broadning.
I have vague memories of reading the derivation of the power picked up by a dipole where it was shown that in the perfectly matched case half of the energy went into the load and the other half was re-radiated. If this is a true memory, you will get at most half of the transmitted power at the receiver.
flatulent said:Right. The 1/ d squared is for the case when only part of the wave front is captured.
For your satellite system, the pointing problem will be large. Many years ago there was a project to power small airplanes that used electric motors. Microwave signals were sent to them. It never worked properly.
flatulent said:There must have been several groups doing the microwave powered airplane at different times. The one I know about was 40 years ago. It was not economical.
flatulent said:On the satellite power collection, there has been the objection that if the pointing became defective the high power microwave beams would be pointed at cities and damage the health of the people and possibly start fires.
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