On 31/07/13 13:54, Jim Lux wrote:
Yes.. You put a gain antenna on the space craft, so for the same tx power, you get the same flux density on the ground. The gps height was chosen for a variety of reasons. It is out of the debris band, for one. There's also a tradeoffs on launch costs, etc. GPS world magazine had a great multipart article on the history and design last year
The GPS birds have a directivity in their antennas to start with, it performs a first degree compensation of the distance change to signal strength, so the GPS bird transmit stronger in a circular lobe on the edge of the earth than straight down.
Doing the same for a GEO sat bird is trivial. The antenna changes the geometry just a tiny bit to achieve it, as the distance difference isn't all that large.
Those interested should play around with NEC2. :) Cheers, Magnus _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
