Cross checking solutions to the beamed Microwave problem

I'd suggest you pick up a copy of "The High Frontier" by O'Neill,
or "Colonies in Space" by Heppenheimer. Both books go into a lot of
detail about SPS.
And a good on-line resource is the SPS section of the PERMANENT site: http://www.permanent.com/p-sps.htm
Regards, Mike Combs