[Elecraft] ?ELECRAFT NVIS field day?

[Bill Parsons]

Thanks Jim.

I was glad that Dean deviated from the usual zero dB reference style of
many ARRL antenna patterns and addressed NVIS propagation for the EmComm
(Emergency Communications) audience with signal levels over geographic
regions and graphs with your style of everything plotted on the same graph
such as in fig. 3 for easy comparison.

He provided frequency choice guidance for both high and low solar activity
periods for nighttime and daytime propagation, as well as clear portable
and home / base station antenna height recommendations. It was a basic HF
NVIS cookbook for field EmComm operations antennas.

73, Bill  AF6AE

On Sun, Dec 19, 2021 at 3:18 AM Jim Brown <jim at audiosystemsgroup.com> wrote:

> Thanks Bill. I haven't seen this piece, but Dean is a good friend and
> smart engineer. Yes, low antennas have the benefit of rejecting low
> angle "stuff" that may be annoying. But it's important to differentiate
> between RX and TX, and TX is all about maximizing signal strength in
> desired directions.
>
> A major shortcoming of all ARRL presentation of antenna directivity is
> that it normalizes them, by setting the max value on the plot to 0dB.
> But what you lose is the ABSOLUTE value. My work avoids that, by
> presenting data for all variations of an antenna on the same graph,
> making clear the advantage of one height over another ON TX.
>
> But RX is VERY different. I often listen on Beverages at 40M and below.
> Their signal is weaker, but their directivity brings desired signals out
> of noise. When I visited N6AA several years ago, he showed me a
> ground-hugging Yagi he used to reject noise from civilization the valley
> below him. No way would he have transmitted into that antenna, nor would
> I have transmitted into my Beverages.
>
> 73, Jim
>
> On 12/19/2021 2:23 AM, Bill Parsons wrote:
> > Take a look at Dean Straws NVIS article (with color graphics) in the
> > December 2005 issue of QST for a discussion of optimizing antenna height
> > for NVIS based on signal to noise ratio and region you wish to cover.
> Most
> > if not all of that article appears in the 23rd and 24th editions of the
> > ARRL Antenna Book with black and white graphics.
> > 73,
> > AF6AE
> >
> > On Sat, Dec 18, 2021 at 1:04 PM Bill Mader <billamader at gmail.com> wrote:
> >
> >> NVIS information is almost always anecdotal and a myth, more than
> science!
> >> As I have told many participants in many presentations, "If you think
> >> lowering your antenna will make your signal stronger, expect your QSL
> cards
> >> to arrive on a unicorn."  How many of you looked at Jim's, K9YC,
> >> explanation?  Probably too few.
> >>
> >> 40m is near the upper limit of NVIS and currently, it is often below the
> >> NVIS frequency.  At this point in Cycle 25, I frequently can't copy
> >> stations within 150-250 miles away on 40m here in NM.  The ones I copy
> best
> >> have the highest, NOT lowest, antennas.
> >>
> >> Note, as shown in Jim's paper, an 80m dipole at 60 ft. provides the
> maximum
> >> NVIS signal while at one at 90 ft. is just 1 dB down.  Having operated
> with
> >> an 80m dipole at 75 ft. on an Air Force RADAR site, my 100 Watt signal
> was
> >> almost always stronger than those with lower antennas around MI.  Yes,
> that
> >> is anecdotal, but it agrees with the science as modeled in Jim's paper.
> >>
> >> I have yet to read of anyone's scientific data showing their 10 ft. high
> >> dipole worked better than their 30 ft. high dipole on 40m, to say
> nothing
> >> of similar 80m dipoles.  If you have two WSPR transmitters and have
> >> antennas at these heights, gather some data.  Both transmitters must
> >> transmit the same level signals at the same time over time to collect
> >> meaningful data, assuming everything is equal.
> >>
> >> I once worked a station in Italy on 20m SSB with my KX3 using my mobile
> >> antenna.  I did not replace much better antennas at home based on that
> >> anecdote.  Neither have I received any QSL cards on unicorns although I
> do
> >> have a unicorn graphic in some of my antenna presentations.
> >>
> >> 73, Bill Mader, K8TE
> >> New Mexico QSO Party 9 Apr 2022
> >> Secretary/Treasurer and Past President, Albuquerque DX Association
> >> W6H NM Coordinator, Route 66 On-the-Air 10-18 Sep 2022
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:Elecraft at mailman.qth.net
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to bparsons.ieee at gmail.com
> >>
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to jim at audiosystemsgroup.com
>
>