I am the director of an NGO building out independent radio networks in
Afghanistan. The combination of geography and security problems, as
you can imagine, are ferocious. As a result, we need to examine a lot
of different technical options and I would like to ask the group some
questions:

1) How can AM be made more one directional than another? We might want
to put strong AM signals in towns near Afghanistan's borders but
cannot antagonise neighbours by having large signal spillage into
their territory. What are cost implications of channelling an AM
signal in this way?

2) How far can an STL wireless transmission reliably broadcast? I
understand most STLs are wire, but there are also wireless STLs using
the 940-950 Khz band. Could we use this wireless STL to spread signal
to repeater networks across mountains where FM would be difficult?

3) How far could a big FM signal reach, assuming little constraint on
power?

4) In FM repeater networks, how many links down a chain can a signal
reliably be put through? Are repeaters normally only a one stage
phenomenon, used like spokes in a wheel, or can you set up a chain up
and down a long valley for example?

5) Does anyone know about renting space on satellites? How much it
would cost to have a 24 hour audio channel beaming down to receivers?
How much a single uplink mechanism might cost, and receiver dishes?

Many Thanks

John