Charles hi,
Our own Joel W5ZN and Frank, W3LPL has mentioned more than a few times that 30-50 feet is good for sporadic E and for not picking up ground noise.
F layer may or may not be a different game? However, if it were me, I would optimize for the Es! IMHO, there is very little F layer stuff on 6m and even at a lower height you will do well with a gain antenna! There are maybe one or two F layer openings last
year.
Try these links:
Even a few years ago when Joel put up his EME 6m array, he talked about the magic height on the magic band, hihi.
BTW, I have seen over the years impressive rotating towers lined with only 6m arrays. That would be cool to go through the stack on each opening!
W5KI Steve made FFMA on modest height antennas! Some I think were only on pushup poles! Steve is one of those quiet Elmers within our club, but knows his stuff!
73 de jay/w5jay..
FYI to those that might not know...Im sure there are many here that is aware.
As I was putting up the last tower and antennas Ken with JK antennas ask about 6 meters, and I have a 7 ele 6 meter antenna on the 89 ft US tower, with the tower up the antenna is around the 95' agl.
Ken told me I was to high, the 6 meter skip layer was about 54'agl, so this AM I did the test, I lowered the 6 meter antenna down to close to the 55 ft AGL area.....Im now seeing half dozen south america dx stations, up from 1. OK the antenna guys knows
their stuff....I have learned something.
73
KF5TL