I got up at 3:00 on Monday morning, expecting to antenna test for
about an hour and then DX until dawn as per usual. I did that first
hour of antenna testing with very interesting results, but at that
point, I pulled the plug. Conditions were down considerably from
Sunday and down even more from Saturday morning, so I said What the
heck! and dived back under the covers for three more hours of sleep
before taking down all six masts, accompanying wire, coax, power
feeds (for the K9AYs) and general junk. By 9:30, I was one tired
puppy, but on my way back home. I arrived here on Orcas Island at
5:30PM, as usual. Boy, that makes for a very tough day at the end of
the DXpedition.
So, the 79 or so stations that I logged the first two mornings are
it as far as my contribution to the cause. I'll upload the
loggings to the appropriate places in the next 24 hours or so.
The final A/B tests done Monday morning were quite revealing, though
the results were largely those that were expected. The K9AYs had
produced very consistent 30 dB nulls with a few approaching forty
degrees. They were exactly 40 meters apart and were 35' x 15' high
squashed Deltas. The combined included area is 525 sq.ft. I shortened
the previous 60'x17' Super Loops to 30' x 17' and maintained the
maximum spacing. So, the new spacing was 45 meters, center-to-center.
The new smaller Super Loops out-gained the K9AYs only about 3 to 5
dB... maybe a little more in a few cases. That 3-5 dB additional
gain was present from top to bottom of the dial. The major
differences were in F/B ratio across the dial, nulling specific
stations on the back side, and in narrowness of front lobe. In all
of these parameters, the Super Loop was considerably superior to the
K9AY. I rush to point out that this is not a general condemnation of
the K9AY... It was working against four radials that were laid atop
damp sand and were operating as a much less than perfect ground. In
situations of good grounding, the K9AY's ability to be switch
reversible is a non-paralleled advantage in domestic DXing and a
handy attribute even in shore side trans-oceanic DXing.
However, it this situation of shore side DXing from rocky or sandy
beaches, the use of antenna elements THAT DO NOT REQUIRE GROUNDING
just makes all kind of sense. On top of that, array elements made of
Super Loops (or KAZs, or flags or pennants) that themselves,
individually, offer significant directionality is just that much more
reason to favor them in shore-side situations.
I made several careful runs up the band, noting channels where one or
the other antenna was OBVIOUSLY better. I made note of 15 channels.
In each and every case, the Super Array was the one that was
superior. In some cases, it was clear that it was gain that was
making the difference. In others, it seemed that the biggest
advantage was S/N. Looking at narrowness of front lobe I compared the
two systems on 690 (about 20 to 30 degrees off the front side) and
there was a clear advantage top the Super Loop. There was no
difference on 1130 (further to the right, but still front lobe) and
there was a slight advantage to the Super Loop on 1600 (front lobe);
so, to, 900. Backside nulling was noticeably better on the Super
Loops... about 10 dB or more. It was particularly noticed on 810,
1080, 1530 and 1440. All in all, the array of two Super Loops with
twice the sail-area, proved consistently superior to the K9AY array
in these tests.
That is it from my most recent DXpedition to Grayland. I'll get the
loggings up in the next day or two.
John Bryant
Grayland, WA
Winradio 313e and two NWterly Wellbrook Arrrays
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