XPost: sci.space.policy   
   From: henry@spsystems.net   
      
   In article <58866faa.0401251618.41995408@posting.google.com>,   
   Zoltan Szakaly  wrote:   
   >You guys can more efficiently transmit energy using microwave   
   >antennas. You can get 60% efficiency by radiating microwaves onto an   
   >antenna that is equipped with microwave diodes.   
      
   Better than that, actually.  Unfortunately, microwaves lose badly for   
   long-range transmission except at very high power with very large   
   receiving antennas.  The longer wavelength -- five orders of magnitude   
   longer than light -- means it's much harder to form tight beams.  So you   
   end up having to use very large antennas on both ends, and that's just not   
   practical unless you're sending a whole lot of power.   
      
   Note that solar arrays are 50%+ efficient on laser light, if the wavelength   
   is chosen carefully to match the solar cells.   
   --   
   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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