Quote:
Originally Posted by kato13
Since I was the originator of the Morrow discussion I felt I should add my initial feelings on the issue.
Low frequency transmissions should not be a problem over the horizon given that most of the transmitters will be off line.
An AM antenna with 50,000 watts on the Sears tower (~1500 ft in Chicago) would probably be able to reach Maine, Texas, Georgia and Utah if there were not other transmissions on a similar frequency. This is of course a one way transmission and would probably be limited to voice.
As frequencies go higher the LOS limits become more apparent. If you start to get in the realm of data transmission frequencies then you are not going to be able to send that information over the horizon. Two way communication (with the units having less wattage) would also be assisted by some sort of repeater.
For the Morrow Project high density transmissions would be a must so something to replace satellites would be a necessity. Transmission of census data, schematics for repairs, updated fallout information, weather station data and video information are just some of the things that I can see needing these higher transmission levels.
Answering the other point that was brought up I agree that Helium would probably be most abundant in the areas from Kansas (where some NG fields are above 2% He) to Texas. That area would have the least difficulty acquiring it.
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Line of sight, you get 54.2 miles for 1500 feet but at AM radio frequencies, the signal follows the curvature of the Earth as well as bounce off the ionosphere at night. Here in Pittsburgh, I can get 1100 (WTAM) out of Cleveland and even 760 (WJR) out of Detroit during the day.