wrote
On 160m, many think they can elevate a vertical 20
ft or so, and use maybe 4-8-10 radials to get good
performance. It just doesn't work that way. At such a
low height in WL, they need almost as many as a ground
mount.
__________

You may be interested in the paper linked below, which reaches
a very different conclusion, verified by field experience.

NEC models of this system in the broadcast band with the radials elevated 20
feet show gains equal to those using a classic broadcast buried radial
ground system. And if this true in the broadcast band, I expect it is true
for 160 meters.

http://www.nottltd.com/ElevatedRadialSystem.pdf

RF