Here is some fresh data on my Vertical Dipole versus my Double Zepp. This
was run last night and is typical of the reams of comparison data that
I've accumulated on 40M.
My methodology: I find a clear frequency, and after a couple of QRLs make
a series of three CQ messages, spaced 5 seconds apart. Once the first
antenna is checked, I change frequency by a few kHz and repeat the same series
of CQs with the second antenna. I alternate which antenna I use first in
case that might somehow skew the data.
I create a printout of the RBN responses and determine which responses are
common to both antennas and compare those reports. I also note which
stations were received by just one antenna or the other. The data is
remarkably consistent.
Antennas: 180' Double Zepp, 30-35 feet above ground. This is a charmed
antenna. I've been at this QTH for almost 20 years, and have tried
countless antenna designs, and this is the best I've ever used, great even on
160M
considering its length and height. I have a 40M inverted Vee with apex at
40' which rarely beats this antenna. This DZ is strung above the route for
neighborhood underground utilities, and has a road and green belt in the
foreground to the east. This may provide something of a counterpoise. I've
won the Low Power NA Sprint and had numerous top five and top ten
performances thanks to this antenna.
The Vertical dipole is 25' long with 42" square hats on top and bottom.
It is tied to a tree limb, and is pretty much buried in a stand of trees.
It is fed with 300 ohm ladder line.
Here is the comparison data compiled between 0303Z and 0305Z. Vertical
dipole was the first antenna tested. Here are the results by receiving sites:
Station Best Antenna dB Difference
DR1A DZ 10
F5MUX VDp 7
V51YJ Equal 0
EA4TX VDp 2
WA7LNW DZ 5
N4ZR DZ 1
W4KKN DZ 6
KM3T DZ 3
K1TTT VDp 1
WZ7I Equal 0
NC7J DZ 2
K3MM VDp 4
NQ6N VDp 3
W3LPL DZ 1
NY3A VDp 9
KQ8M VDp 2
N0TA DZ 7
N7TR Equal 0
N6NC VDp 4
N6WIN VDp 1
K8ND VDp 2
Reverse Beacon Reports for only one antenna:
DZ (1) W8WTS
VDp (3) DL1EMY, WB2LSI, GW8IZR
dB advantage over all common stations between antennas (the sum) is equal
at 35 dB for each antenna!
DX advantage: VDP had the advantage on 2 DX stations, DZ one and one was
equal. Two of the three beacon stations reporting exclusively on the VDp
were DX. The DZ was heard exclusively on only one reverse beacon, and it
was stateside.
These are completely unexpected results. I was hoping to find something
that would be within a few S units of the DZ to use as a backup, but this
antenna is more than its equal. Daytime results a quite similar,
surprisingly. I haven't paid as close attention to them as 40M is a money
band
primarily at night, but during daylight periods of high absorption, the DZ
seems
to do 2-3 dB better.
I was quite flummoxed after a rare but heavy rainstorm. The DZ was
showing an average 5-6 dB advantage shortly after the storm. I surmised that
somehow the wet ground was providing a better counterpoise for the DZ. Recall
I mentioned that the VDp was nested in a stand of trees, that seemed to
actually be the problem, as results normalized after two dry days.
If there is one thing I can say with some authority, I know which antennas
have worked well for me. I am limited to about 35' max height and 100' max
length in my lot (one leg of the DZ goes into the lot of a very awesome
and supportive neighbor!). My antenna effort is the sub optimization of
some rather limited choices, when I find something this good, especially when
it takes so little real estate, it is truly exciting. My mind now wanders
to a multi-element array for 40M. I also wonder how I might apply this
concept to a small 160M vertical.
YMMV, but I've got abundant evidence that it works for me.
Paul, K5AF
In a message dated 9/22/2012 12:05:27 P.M. Central Daylight Time,
armstrmj@aol.com writes:
Well Tom, all I can say is that it works...... Here is more data.... The
mast was a wood pole about 12 feet long and the feedline was buried, so
there wouldn't be much radiation from them. There could be some from the base
of the vertical to the dirt via the feedline, but that would be all that
was possible. Well, there could be some while it is buried in the dirt, too,
of course..... Not sure how much since I had a current balun close to the
feedpoint.
I do try to think of things like incidental radiation in my setup. Can't
always do much about it, but I try. The point here was not modeling, it
was experience..... Of which I have considerable. I have used these antennas
alot (half wave verticals) during my 52 years. They have never
disappointed from an actual performance point of view. I will say, however,
that
they seemed to work better from Hawaii and my house was VERY close to the sea
there almost 360 degrees. But ANY antenna seems to work better when
surrounded by sea water, so that is kind of a given.
If we are talking a modelling contest, then I haven't got a clue with all
the variables. I can just answer someone who asks if I used one..... The
answer is no.... I have used many of them and they ALL worked well enough to
make me want to keep them. That is about a good as I can say for any
antenna :) :) BUT I do hear you, which is why I said what I did about the
installation..... All of it may well apply to my success with the antenna.
Mike AB7ZU
Kuhi no ka lima, hele no ka maka
On Sep 22, 2012, at 5:54, "Tom W8JI" <w8ji@w8ji.com> wrote:
>> A ringo ranger is a vertical half wave using "end feed" and they work
>> great. I prefer end feeding, using hte method of the ringo (which is
>> easy to scale to other bands). I purchased the 10 meter version some
>> years back and built ones for all bands to 20 meters by scaling the
>> end-feed arrangement.
>
> When we end-feed a vertical like that, without radials, the system can
have as much radiating current on the mast and feedline as the vertical
itself has. This can do all sorts of things to the pattern and gain, because
the feedline and mast become a major part of the actual antenna.
>
> There is a basic electrical rule that cannot be broken. In order to
force current up into the vertical at the feedpoint, an EQUAL current has to
flow back down into the coax shield, the mast, radials, or something else.
>
> We are kidding ourselves if we look at an end-fed antenna without a
ground system and proper feed isolation and assume only the vertical is the
radiator.
>
> This is why, later in the Ringo's life, Cushcraft added a kit that added
radials to the Ringo.
>
> 73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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