[TowerTalk] NVIS antennas Re: dumbing down

[Gary]

Jim Lux wrote:

 >>So what? Groundwave is zero degrees, not 15 and certainly
 >>not 45 degrees.  A horizontally polarized signal at 3.5 or 7
 >>MHz has virtually no ground wave signal at all.
 >
 >
 > I think you mean a horizontally polarized antenna doesn't radiate any
 > ground wave? I can propagate a horizontally polarized signal parallel to
 > the ground perfectly well (which most TV broadcast stations depend
 > on).  Whether a horizontal dipole over ground does it well is really the
 > question, and I readily concede that an idealized horizontal wire 
doesn't
 > have any radiation at zero elevation. However, a "real antenna" over 
"real
 > ground" that isn't perfectly flat may radiate at zero elevation angle.

Jim,
I think he does mean "does not propagate on ground wave". Horizontal
polarization will not support a ground wave signal. It gets shorted out
by the earth. A vertically polarized signal does not have that problem
and will follow on the earth surface.

A TV signal does not propagate by ground wave. It is line of sight with
some atmosphere ducting and bending.

There are sometimes disconnects in terminology when talking about ground
waves. In this case "ground wave" really means "surface wave", which to
some is different than ground wave where they might be talking more
about line of sight propagation.

73
Gary  K4FMX