On 6/15/2012 7:23 PM, Boomer wrote:

If I had to bet, I'd say it's the change in pattern.

An article on NVIS antennas appears in the December 2005
QST......



I guess my hunch on the difference being pattern related
panned out..
I've used horizontal loops on the low bands. But I came to the
conclusion they were generally not worth the extra trouble, vs
a dipole. I could barely see any difference here from the usual
dipoles I ran. And if the signal is stronger at one angle or direction,
vs another antenna, it's weaker in another. So it's all a compromise.

On the low bands, I came to the conclusion my favorite antenna for
mostly NVIS and medium path work was the turnstile.
Which are crossed dipoles. You can feed them in or out of phase
for either dipole patterns, or with them 90 degrees out of phase,
for a fairly round omnidirectional pattern.
I like to do well to the close in stations, but also the ones
farther off too.. So even if I used a loop, I would generally
try to get it as high as possible.
Which I also do using dipoles, or turnstiles.