Steve Heller's Amateur Radio FAQ Page

How dependent are amateur radios on the power grid and other infrastructure elements?

> To what degree does ham radio rely on the
>repeaters?  If there is an extended power outage, would the repeaters
>continue to function (they are passive) or not (they require
>electricity)?

  Repeaters (automatically controlled relay stations that forward
messages from one amateur to another) are indeed active devices that
rely on electrical power being supplied.
  Luckily, long-range communications via amateur radio do not rely on
repeaters, as the range of even the best repeater is limited to
perhaps a hundred miles. Long-range communications rely instead on the
ionosphere's ability to refract radio waves back to earth (the "skip"
you refer to). The ionosphere, of course, is a passive device that
requires no electrical input. Under the proper
circumstances, it is entirely possible to transmit and receive
messages over thousands of miles without any intermediary relay
stations; I have personally communicated with someone approximately
1500 miles away on about 100 watts of power.

Do amateur radios depend on satellites?

>Aren't the ham radios operated by use of a satellite?

  No, amateur radios do not depend on satellites. It is true that
there are satellites used by amateurs to communicate, but that is a
specialty rather than the normal method of communication. The vast
majority of amateurs do not communicate via satellite, and even those
who do can almost always use an alternate method of communication via
the normal ionospheric refraction path that allows long-range
communication without any intermediate stations.