Your Shoulder' with Beverages
A Comparison Test
John H. Bryant
Over the past 15
years, I've been using relatively short Beverages,
unterminated, at my home QTH in Oklahoma,
USA. These low wires (average height about 6 to
8 feet) vary in length from 450 to 750 feet. I've
found that such wires were useable directional antennas
with very good lobes off of each end.
For about four of
those years, I operated a "half-wagon wheel"
of Beverages of that general length with the wires
running East, SE, South, SW and West from a central
point in my back yard. At the time, I was primarily
interested in SWBC DXing on the Tropical Bands (from
2.5 to 5.5 MHz.) and could use each antenna "directly,"
of course: for example, I could use the SE wire
to look to my southeast for South America and for
southern Africa. Happily, I could also use that
SE antenna "over the shoulder" to look
to my northwest along my Great Circle route
to East and South Asia. In essence, by leaving the
Beverages unterminated and thus bi-directional,
I was operating quite nearly as if I had twice as
many Beverages spread out in a full wagon wheel.
Using a simple unterminated single-wire
Beverage antenna as a bi-directional device is well
known in the literature, of course, and carries
with it at least two inherent penalties:
By its nature, an unterminated
Beverage is bi-directional and thus does not
reject anything off the backside
The signals coming "over the shoulder"
from the normal backside of the antenna travel the
length of the Beverage, going away from the receiver,
hit the far end and are reflected back to the receiver.
There is an inherent signal loss in this
reflection and longer trip. Authorities and modeling
programs differ slightly as to how much the "backside"
signal is attenuated, but most tend to focus on
4 to 6 dB.
Over the past year, my Northwest
MW DXing buddies and I have become quite interested
in reverting to "12 Volt DC DXing" from
automobiles and campsites on the Pacific seashore.
Our beloved Grayland Motel is for sale and we are
anticipating the loss of that near-perfect layout,
with antennas of optimum length running in the correct
directions and terminated virtually in the surf
at high tide. In the near future, we foresee many
situations where we will be able to get our vehicles
quite close to the shore, but where we will be so
close that there simply is not room to run a Beverage
out toward the sea. There are a number of familiar
venues, however, where we could be DXing very near
the shore itself and run antennas directly away
from the beach inland through the scrub or forest
laying behind the beach itself. Unterminated, we
could then use these antennas to DX the far Pacific
shore "over the shoulder."
As we discussed this idea, there
was quite a bit of disagreement as to just how much
loss this "over the shoulder" approach
might entail. Some of us held with the published
"4 to 6 dB" figure
. and felt this
to be a negligible amount, while others held with
equal sincerity that the loss could be much greater.
I volunteered to run a field test this winter in
my home area of central Oklahoma where the roads
run, literally, straight for mile after mile and
where the Southern Prairie is more or less one big
flat cow pasture
. ideal for testing directional
My automobile/DX shack was parked
at the crest of a very gentle hill, with the antennas
extended North and South from the vehicle, along
the roadside tree line and suspended from the lower
branches. The road runs absolutely North-South.
The antennas were two new 500 foot Beverages. When
laid side-by-side, one wire was about 3 feet longer
than the other, but was not trimmed (the South antenna
was the longer). The slope of the hill was equal
in both directions and was such that the far end
of each antenna was about ten feet lower that the
automobile. The Beverages each went to one of a
matched pair of new impedance transformers, then
through identical 6' lengths of coax to an antenna
switch and thence to an NRD-535 which was used to
compare signal strengths on each antenna for a number
The stations to be measured were
selected to be spread across the MW dial and to
be those laying directly to the North or South of
my location. Each station that was measured put
in a moderately strong signal, varying in strength
from 1280-Arkansas City, KS which came in at around
S-8 to 640-Norman, OK, which put in an S-9+10 dB
The tests were run at solar noon,
with no thunderstorms present or audible on the
band. The signals were exceptionally steady and
were each the only signal audible on the channel.
The signal strengths were measured twice, about
10 minutes apart and are (both) presented below
in a relativist chart.
to the SOUTH
on both antennas!
||- - -
||+6 dB, +6 dB
||- - -
||+3 dB, +3 dB
to the NORTH
||- - -
||+6 dB, +3 dB
||Wow, the reverse
||+3 dB, + 5 dB
||- - -
||- - -
||+6 dB, +4 dB
||Again, the reverse!
||- - -
||+3 dB, +3 dB
NOTE: Two tests were also done
to the side of the antennas: 1600 kHz., Cushing,
OK to the due East came in about 3 dB better on
the North antenna; 960-Enid OK, to the West-Northwest
also came in better on the North antenna by about
2 or 3 dB.
With the exception of the slope
of the ground (DX shack at crest of gentle hill,
each antenna sloping parallel to the ground downward
about ten vertical feet over the 500 foot length)
the two antennas were virtually identical, but running
in opposite directions. Given that the signals were
fairly equal on both antennas and that the measuring
instrument (NRD 535 S-Meter) was fairly crude, precise
results were not expected. In fact, the relative
strength measurements of the stations to the SOUTH
were about exactly what I expected: two of the three
stations were stronger on the southerly antenna
by 3 to 6 dB. The measurements of stations to the
North, however, presented a real surprise: four
(580, 1280, 1330 and 1580) were 3 to 6 dB stronger
on the South Beverage that pointed away from
them. This was so surprising to me that I exchanged
the two lead-in + impedance transformer combinations
prior to taking the second set of measurements.
The results were identical except for a 3 dB drop
in the 580 kHz. reading.
One could still argue that, for
some reason, the southern Beverage was just "working"
better. That was my reason to measure the only two
nearby signals that come in from nearly straight
East and West. As you see from the note above, the
two side signals were both received better on the
Just exactly why these anomalous
readings came about could be the subject of endless
speculation. Happily, that discussion is not at
all relevant to the purpose of this particular field
test. The goal was to determine whether the backside
losses of relatively short Beverages were negligible
or large enough to be significant when forced to
DX "over the shoulder." Based on this
comparison test, I feel comfortable using a short
Beverage and DXing over my shoulder, when better,
more classic arrangements are not possible.
Above is a two-layer photo-montage
of the new campsites now under construction at Grayland
Beach State Park on the Pacific Coast on Washington
State. Foot and vehicular traffic on the beach,
even at night, prevents us from running antennas
on the beach itself. As you may note from the montage,
the new campsites are too close to the beach to
allow us to deploy a full array of classic "direct"
terminated Beverages from any single new campsite
in the park.
The array of blue lines at the
upper-right of the montage indicate a deployment
of the three beverage pattern that we find most
effective for DXing from the Pacific Coast (NW,
West, SW). Each antenna, as indicated is 500 feet
long. The antenna running to the NNW is a classic
terminated Beverage, the other two are "Over
the Shoulder" unterminated affairs.
Finally, some readers will surely
ask why we do not simply adopt more compact beach-side
antennas, such as the K9AY, Flag or KAZ large loops.
We have done some rather careful comparisons between
these antennas and our normal Grayland Beverage
array and have repeatedly found that the Beverages
were superior. This was true even when the same
antenna comparisons had been judged "similar/equal"
at inland locations. Additional comparisons will
be made this summer and fall.
Published on March