[TowerTalk] Determine cost-effective tower height

[Andreas Hofmann]

Hi,

I have decided I need a tower to get better antennas up in the air. Thinking about the SteppIR DB 18, 40m 2 el, 20 and up 3el.  Now, my property slopes pretty much in every direction by 5 degrees.  I need to determine a proper tower height without breaking the bank.

I was told I should run a computer program to figure a good height of the yagi for my most important directions/DX locations.  In fact a friend of mine did the same (on a similarly sloping property) and he found out that a 55 foot tower would be similar to a 120 foot tower on a flat ground.   Hence he put up a 55 foot crank up mast and it is rocking.  He forgot the program he used.

So, what tool can I use to find the optimal (not maximal) height of a tower that would work well here?
Also, the tower would be setting on the side of the house with a metal roof (roof about 15 feet high), not sure if this would matter...

Thanks
Andreas
KU7T