Hi Jay, I dont think you need worry about angling signal upwards for
skywave. It will only exceed groundwave strength at greater than about 600
to 700kms according to the meaurements I have seen.  The steeper it goes,
the deeper it goes (into the D-layer) and the more absorption it suffers.
Hence no skip zone on LF. I think this distance is fairly indepenent of
power level. If you concentrate on getting good strength on the ground about
a mile away from the aerial, you cant go far wrong.

Cheers de Alan G3NYK
[email protected]
http://www.alan.melia.btinternet.co.uk