Topband: RE: skewed paths

Tom Rauch
Tue, 18 Sep 2001 09:56:30 -0400

Hi Milt and all,

First on propagation. Very clearly signals "skew" (to make it clear, 
Bill and others call this longpath but I reserve the term longpath for 
the "long way around the world" to avoid confusion with between a 
skewed short path and a true longpath).  

Scattering at the ends of the path makes no sense at all, because 
if it was scattering there would have to be dumb luck at both ends 
of the path for headings to be skewed into the SAME area of the 

The fact both ends beam into the skew obviously means the path 
itself is skewed someplace far from the stations at each end, or the 
people involved are the luckiest people in the world to have such 
weirdly repetitious luck that both ends just happen to bend the 
same amount at the same time. 

On measuring angle.......

While I appreciate all the interesting comments, the fact is even 
with a hundred acres of receiving antennas and years to 
experiment, I can't tell you if weak signals are high angle or low 
angle or how they get here. I can tell on stronger signals, but only 
through years of work and the ability to phase arrays that are 
spaced large distances apart...and the ability to select high (~300 
feet) dipoles and low dipoles (~50 feet and 150 feet) that are out in 
the clear by themselves. 

The following are facts we often miss:

1.) A dipole does NOT null vertically polarized signals off the ends. 
It nulls them broadside to the dipole. If you want to install a dipole 
to null local groundwave noise, it must be broadside to the 
noise....not off the end.

2.) When 160 meters is open, noise comes from many directions 
at once. You might be unfortunate enough to have a dominant 
noise source locally, but in most cases noise that propagates in 
sets the S/N ratio. This noise always comes from multiple 
directions, although there may be a generally "hot" direction.

3.) A longwire array like a Beverage has many spurious lobes that 
are much less attenuated than the null area of a dipole compared 
to the main lobe. None of use know in *detail* what the patterns of 
our Beverages are, because they are greatly influenced by earth 
and what is around the antenna.

If distant signals were at times high angle, I would expect my 
verticals to be "dogs" and low horizontals to whip them during 
those times. That virtually never occurs. When we have those 
"horizontal nights", the high dipole always beats the low 
dipoles..leading me to believe the wave angle never gets higher 
than ~40 degrees. If it did, the lower dipoles would have stronger 

73, Tom W8JI