The other thing I have noticed with my BEV's and BOGs is propagation
mode can cause quite a bit of variability in RDF or F/B. Using other
than a local station for measurement can give inconsistent and confusing
results. Often the RDF on some gray line signals will not be as good
compared to later in the evening. I attribute (but have no way of
actually measuring) this to be possibly a a function of the arrival
angle of the signal . I have seen several references to the possibility
that gray line propagation is sometimes thought to the result of
"ducting" and the signals are arriving at higher angles than signals
arriving at lower angles via more common F-layer propagation ??
Dave
NR1DX
On 8/24/2022 10:54 AM, David Olean wrote:
On 8/24/2022 9:03 AM, w5zn@w5zn.org wrote:
Hi Kenny,
Over the past 12 or more years I've conducted numerous comparisons of
different receive antennas on the low bands. I'm fortunate to have
enough land to lay all of them out with adequate spacing and perform
A/B comparisons. I am in a rural area that is relatively quite
although over those 12 years I have seen the noise floor gradually
increase up to 5 dB in a couple of directions! A battle I continually
fight!!
One thing I have emphasized over the years is the realized
performance of any antenna will be different depending on the
geographical location. Another point is most times radio amateurs
have unrealistic expectations of what the performance of a specific
antenna will be.
With that said, I have compared the antenna you are considering at
your QTH here at W5ZN with a single Beverage that you currently use.
I could not document any noticeable improvement between the two.
That's not to say there wasn't any improvement, it just was not
noticeable.
I begin to notice a difference when the RDF is increased by more than
1.5dB. I realize this is splitting hairs when we're claiming only a
few tenths of a dB difference but that is based on my real world
documented comparison.
The most significant improvement I have documented is moving from a
Beverage to a phased vertical array. The Hi-Z and BSEF 8 vertical
arrays are the top, with the HiZ outperforming the BSEF by just a tad
due to the HiZ-8's improved F/B and F/S performance. The YCCC-9 is
also an excellent performer. My measurements have also confirmed the
modeling data for all of the arrays. I presented this data at Contest
University - Dayton this year.
So my recommendation is to erect the new Beverage and give it a try.
You may very well notice a improvement. If constructed correctly, it
should be an improvement even if only a few tenths of a dB RDF and it
won't be a loss !
73 Joel W5ZN
On 2022-08-23 14:07, Kenny Silverman wrote:
In a rural area with no significant man made noise, if you redesign a
beverage for better RDF when do you start to notice a difference?
I’m considering upgrading my single EU beverage at 625’ (190m) to a
pair in echelon where will each be 550’ (168m) with 20’ (6m) spacing
. The increase in RDF is 0.8 dB - will it be noticeable?
I realize if there’s noise in a direction where you reduce the energy
you will better hear the difference , but my EU beverage is quiet.
Though the F/B change will help with thunder storms off the back.
Overall I tend to receive better than I transmit to EU.
73 , Kenny K2KW
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