On Mon,8/18/2014 1:41 PM, Rick - DJ0IP / NJ0IP wrote:
Jim (B)'s tutorial on 160m antennas is an outstanding guide to antennas for
this band.
THANKS Jim, I hadn't seen this document before.
It is really a great summary of the 160m vertical scenario.
(Apologies to Jim (A) for deviating from his original thread into 160m
antennas).
I assume Jim (B) was referring to the information on this page:
http://audiosystemsgroup.com/160MPacificon.pdf
Right.
What is not pointed out here, nor in nearly every
document I have ever see on this topic is how much better this type of
solution will work (for working DX) than a low dipole or horizontal
longwire.
Did you miss slides 4 and 5?
Low dipoles on 160m are pretty worthless for working DX, but as Steve
pointed out, good for short range communications.
Poor choice of words. They sort of work for short range, but only
because they are not going very far, because they are very inefficient.
Low horizontal antennas have more ground loss.
One of the common misconceptions is that an antenna SHOULD be very low
for short distances (NVIS, Near Vertical Incidence, "cloud-warmer").
In http://audiosystemsgroup.com/VertOrHorizontal-Slides.pdf I show that
the ideal height for short distance (high angle) communications is a
quarter wave. That's 133 ft on 160M. See the graph on slide #19, and
multiply heights by 2. Other things a study of that graph will tell you
is that higher is better for low angles up to at least a half
wavelength. Again multiplying by 2, you gain 6 dB going from 40 ft to
133 ft at low angles, and 3 dB at high angles.
BTW -- When Rick talks about working 35 and 50 countries on 160 from the
middle of Europe and not far from northern Africa, that's equivalent to
working the same number of states and provinces in North America. :)
And when Steve talks about working the UK from Northampton, that's only
200 miles to the border with Scotland, another 200 to the top of the
island, and only 325 miles to the most distant part of Ireland! By
contrast, I'm 500 miles from the border with Mexico, 825 miles from
Canada. It's 2,000 miles to the west or NE before I hit another DX
entity (really states, of course) KH6 and KL7.
73, Jim K9YC
73, Jim K9YC
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|