Jim,
I agree all points.
But if you want to work a lot of countries, I'll gladly swap QTH's with you!
(hi)
On the inverted-L's that I put up, I also worked around 35 US states or
Canadian Provinces in one weekend contest, so it's not like I'm working just
Europe on the antenna.
Jim, I didn't understand the point on slides 4 and 5.
I concur with everything you wrote.
Perhaps you mean where you wrote 130 ft. height for a horizontal antenna is
"low" on 160m.
Well my main point is, we have good dB numbers shown for different vertical
solutions, but there are no dB numbers shown comparing a low dipole at a
typical height one would have in a city - say 50 ft. max, to anything
vertical.
There the difference is larger (in dB) than the difference between a good
vertical and a great vertical.
My point in listing countries worked was to point out how much better it
works when going from a low horizontal antenna to a mediocre Inverted-L
antenna. It is a HUGE improvement. And a good vertical is even better.
It's going to take some days to study the entire document in detail. There
is a lot of meat in it!
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Monday, August 18, 2014 11:57 PM
To: tentec@contesting.com
Subject: Re: [TenTec] 160 Meter Problem
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
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|