Topband: WD-1A 2-way Beverage

[W5UN]

Is anyone here using WD-!A wire for a bi-directional Beverage having
success? I notice that mine performs very good in the forward
direction, but has severely reduced gain in the reverse direction. I
would like to hear if others are experiencing this reduced gain in
reverse direction. I did not notice this with my old 2
wire bi-directional Beverages (which I replaced with the WD-!A wire).

I am not sure I am setting up correctly. MY measured SWR is good
(less than 1.5) in both directions through 10 mHz. Any thoughts will
be appreciated. I am closely following the ON4UN Antenna Book design
and am in agreement with Tom, OH2BEN' who is using the same design.

Dave, W5UN

[Lee K7TJR]

Hi Dave: One look at the specs for WD-1A scares me. I do not see how one could successfully send any RF down one of these wires as a differential transmission line. That is exactly what happens, and what you need in the reverse Beverage mode. The loss of WD-1A at 4kHz can be as much as 5 dB per mile by spec. Lets see thats about 1dB at 4kHz for the average length Beverage. 1000/5280 * 5 dB=~1dB. Using a simple 1 dB for each doubling (2^9 * 4khZ) of the frequency as the spec chart shows, one can expect 9 more dB for a total loss of at least 10dB. It would likely be much worse than this in real loss figures for the cable at 2Mhz. 10dB loss or more in the reverse direction would be very noticeable. I am not certain what it would do to the expected operation/pattern but I am sure it would affect the real versus theoretical termination resistance of the antenna as well. Some real loose approximations here! It is not hard to expect this when it has an approximate 70 ohm transmission line impedance (my guess) and a pure DC loss resistance of 46 ohms in 1000 feet per side!

So let me guess, you see 1 to 2 S-units (6 to 12 dB) difference in antenna gain forward to reverse?

Here is the specs when it was new. What it might be after 10 or 20 years maybe more is anybodys guess.

Oh, and SWR would likely look pretty good as there is a lot of resistive loss here.

"http://www.dscc.dla.mil/Downloads/MilSpec/Docs/MIL-DTL-49104/dtl49104.pdf"

Personally, I would not use this wire.

Lee K7TJR Oregon

[Roger D Johnson]

Post by Lee K7TJR
Hi Dave: One look at the specs for WD-1A scares me. I do not see how one could successfully send any RF down one of these wires as a differential transmission line. That is exactly what happens, and what you need in the reverse Beverage mode. The loss of WD-1A at 4kHz can be as much as 5 dB per mile by spec. Lets see thats about 1dB at 4kHz for the average length Beverage. 1000/5280 * 5 dB=~1dB. Using a simple 1 dB for each doubling (2^9 * 4khZ) of the frequency as the spec chart shows, one can expect 9 more dB for a total loss of at least 10dB. It would likely be much worse than this in real loss figures for the cable at 2Mhz. 10dB loss or more in the reverse direction would be very noticeable. I am not certain what it would do to the expected operation/pattern but I am sure it would affect the real versus theoretical termination resistance of the antenna as well. Some real loose approximations here! It is not hard to expect this when it has an approximate 70 ohm tr

ans

Post by Lee K7TJR
mission line impedance (my guess) and a pure DC loss resistance of 46 ohms in 1000 feet per side!
So let me guess, you see 1 to 2 S-units (6 to 12 dB) difference in antenna gain forward to reverse?
Here is the specs when it was new. What it might be after 10 or 20 years maybe more is anybodys guess.
Oh, and SWR would likely look pretty good as there is a lot of resistive loss here.
"http://www.dscc.dla.mil/Downloads/MilSpec/Docs/MIL-DTL-49104/dtl49104.pdf"
Personally, I would not use this wire.
Lee K7TJR Oregon

Dennis made some actual measurements:

"However, be aware that the line loss is relatively high in the reverse,
transmission line mode. I tested this line extensively at 1.8 and 3.5
Mhz using
approximately 10 watts of power and very well matched binocular core
transformers. I measured a net loss of 5.1 db for 502 feet of line on
1.8 Mhz,
and 8.8 db for the 502 foot run at 3.5 Mhz. The loss in the reverse
direction
goes up significantly at 7 Mhz and higher.

73, Dennis W0JX/8"

73, Roger

[RA6LBS]

Hi Dave!

Post by W5UN
Is anyone here using WD-!A wire for a bi-directional Beverage having
success? I notice that mine performs very good in the forward
direction, but has severely reduced gain in the reverse direction. I
would like to hear if others are experiencing this reduced gain in
reverse direction. I did not notice this with my old 2
wire bi-directional Beverages (which I replaced with the WD-!A wire).
I am not sure I am setting up correctly. MY measured SWR is good
(less than 1.5) in both directions through 10 mHz. Any thoughts will
be appreciated. I am closely following the ON4UN Antenna Book design
and am in agreement with Tom, OH2BEN' who is using the same design.

The WD-1A, as all his brothers all around the world, have some
attenuation at our frequencies of interest (1-7 mhz) when serving
as a transmition line. And that`s the mode in reverse direction in a
bi-directional Beverage antenna. This attenuation is responsible for different
signal levels from "forward" and "back" direction of reception.
The transmission line impedance of WD-1A is around 170 ohms by the way
in Russia, Finland, Germany, UK and Iam pretty sure in US too.

The value of attenuation in a transmition line mode depends on
the insulation material used by manufacture but seems to
be near the same around the world and equals around 6 db per 300 feet
at 1,8 mhz.

Signals from the back direction will be around 9 db down from the
forward direction at 600 feet. And RF signals from Back direction of
reception is not "injected" at feed point, so direct multiplication of
attenuation by length does not play here.

And this prevents us to use WD1A in a bi-directional Beverage longer then
about 600 feets. While there are some reports of success while
using it at a greater lengths. It depends on a noise floor of
particular QTH by the way.

The WD-1A and similar CAN be used while at a modest lengths. Up to 200 meters =
600 feets from my experience and direct A/B test with classic
Beverage antennas. The reverse direction will be greatly
attenuated while extending the line over.

YMMV of course.


The wire is great for its strength , simplicity of installation and
should be regarded as a good starting point for us - small pistols -
who cant make it longer or for some other reasons.

One should remember also the vertical pattern difference at say 6000
and 1200 feet length of Beverage antenna.

And they are still quite usable in a staggered and broadside arrays of
course.

The number of transformer turns using BN202-73 is 2/(2+2), 2/5 and (2+2)/5
for WD1A feed with 50 ohm coax while antenna at 6-8 feets.

When feed with 75 ohm line the numbers are 3/(3+3) 3/7 (or 8) and
(3+3)7 (or 8).

[Paul Kelley N1BUG]

I have been following the recent threads on reversible Beverages
made from WD-1A wire with interest. Results with this type of
construction seem to vary, for reasons yet unknown. I thought I
would take a few moments to summarize my experience with WD-1A
Beverages. My new Beverage "farm" consists of four such Beverages.
They range in length from approximately 500 to 650 feet. I am using
home wound transformers with BN-73-202 binocular cores, as described
by Tomi, OH2BEN. Direction switching is by means of a relay at the
feed point, powered via the coaxial cable.

With regard to gain, my experience has been typical of what has been
reported by others: gain is about 6 to 8 dB lower in the "reverse"
direction. This is somewhat annoying, since I prefer to keep the
signal level about the same on all antennas I use for listening (it
helps maintain optimum S/N ratio without the need to adjust preamp
gain or attenuators). However, the lower gain in the reverse
direction is not a serious problem as long as the pattern remains
acceptable.

Front-to-back ratio has a tendency to be very good in the "reverse"
direction but not as good in the forward direction. A poor ground at
the far (non-feed) end seems to make this worse but even with good
to excellent grounds I still notice some difference in F/B between
the two directions. This may be unique to my particular
installation. All of my Beverages run over uneven terrain and have
some vertical slope somewhere along their length. I theorize this
may result in a different pattern for the two directions. Other
theories include imbalance in the reflection transformers or the
Beverage itself. I am very interested in the experience of others
with regard to F/B of WD-1A reversible Beverages.

Two of my Beverages are "center fed" (actually fed at some
convenient arbitrary point) while the others are end fed. I have
come to prefer feeding somewhere near center when it is practical to
do so. Center feed equalizes gain between the two directions, with
gain for both directions being 3 to 5 dB down in comparison to the
forward direction of an end fed Beverage. F/B with center feed seems
about the same in both directions, but not as good as in the reverse
direction with end feed.

Overall I feel the WD-1A Beverages are hearing well. I am not able
to have conventional single-wire Beverages up at the same time to do
direct A/B comparison. Having had conventional Beverages for several
years, my perception is the WD-1A Beverages work nearly as well with
the exception of somewhat poorer F/B in the forward direction.

Ladder line or relatively wide spaced wires would probably work
better for reversible Beverages, at least in terms of equalizing
gain between the two directions in the end fed configuration.
However, either type would be very much more difficult to work with
in my situation, running over uneven terrain which slopes in every
direction and through dense forest. WD-1A wire is as easy to work
with and keep in the air as a single wire.

On a final note, I have tried to prevent the WD-1A wire from
breaking when (not if!) trees fall on it. At each end point there is
an insulator, followed by a few inches of 18 AWG solid insulated
soft copper wire attached to the end support post (aka tree). This
wire is much weaker than WD-1A and will break with much less tension
than the Beverage itself. The feed or reflection transformer box is
separately attached to the tree, and 1/4" blade quick disconnects
(known as faston connectors in EU I believe) are used in the
pigtails of WD-1A going to the box. This provides a "break-away" end
connection. All intermediate insulators along the Beverages are of a
type that allows the wire to slide through with very little
friction. This strain relief has been tested once so far, and it
worked. Repair took 10 minutes, mostly walking time, and required
only a saw (to cut the downed tree, thus freeing the wire from under
it), ladder (to reach the Beverage termination box), and 12 inches
of the #18 copper wire. More tests may be imminent, as the wind is
really howling today!

73,
Paul N1BUG

[Herbert Schoenbohm]

----- Original Message -----
From: "Paul Kelley N1BUG" <paul.kelley.n1bug at gmail.com>

Post by Paul Kelley N1BUG
. However, the lower gain in the reverse
direction is not a serious problem as long as the pattern remains
acceptable.
Front-to-back ratio has a tendency to be very good in the "reverse"
direction but not as good in the forward direction. A poor ground at
the far (non-feed) end seems to make this worse but even with good
to excellent grounds I still notice some difference in F/B between
the two directions. This may be unique to my particular
installation. ....
may result in a different pattern for the two directions. Other
theories include imbalance in the reflection transformers or the
Beverage itself. I am very interested in the experience of others
with regard to F/B of WD-1A reversible Beverages.

There have been some discouraging reports about signal attenuation of a
WD-1A two wire Beverage used in the reverse mode. Prior to these reports
surfacing, I had ordered a mile of WD1-A and a few weeks ago ordered the
KD9SV transformers for this wire. Even expecting the worse I decided to try
anyway to see for myself if the reverse mode attenuation reports are as bad
as claimed. (Reverse mode reception of NW and NE is my only good option
since the open field lays to the south of my QTH with the ocean or a large
salt pond on the far side of this field.


Setup: I have now two 2-wire 600 foot Beverages running (toward) SW and
about 65 feet apart. Both run in an essentially unobstructed former hay
field now covered with brush and small trees

Beverage #1 uses 450 ohm #16 solid conductor ladderline and is
fed with RG-6
and terminated with DX-Engineering's RBS-1 two coax feed unit and
reflection transformer.
The antenna is 4 to 5 feet average ABG. The reverse direction is
NE toward Europe

Beverage #2 uses WD-1A narrow spaced military field phone wire
fed with dual
RG-6 cables and uses the KD9SV transformer boxes designed for
this wire. Both
boxes have two ground rods and (3) 30 foot spiders.The reverse
direction is NE.

Test Procedure:

During the CQ WW Contest this past weekend I was able to do A/B
switching on over a
100 European stations concentrating mostly on Eastern Europe
stations and beyond in
Asiatic Russian and the Eastern Mediterranean areas. The
switching was with a
Waters"Protax" coax switch.

Test Results:

Never was Beverage #2 inferior to Beverage #1...not once! Both
were equal and even the
weakest signal on either Beverage was equal to the other. Since
the forward direction
(SW) is limited to a few stations in VK and ZL I was only able
to check the forward
direction with 2 stations ZL3IX (morning before the contest) and
VK3ZL the morning
after. (I sure wanted them during the contest but neither was
heard) VK/ZL is the
forward direction and again their was no discernable difference
in performance of either
antenna at this location.

Summary: DX-Engineering makes superb antenna accessories but the KD9SV and
WD-1A field phone wire combo are adequate and less costly to construct.
Other issues include the longevity of the wire itself of which only time
will tell. The WD-1A wire wins in the aesthetics department as the
ladderline is very visible. The WD-1A does not allow internal single coax
switching like the DXE unit. Both manufacturers stress the unused port must
be terminated in 75 ohms. I have tried to test this requirement but so far
have not found that on the shack end makes any difference, i.e. open,
ground, or terminated in 75 ohms.

I know this is not a very scientific test but it is what I have observed in
testing this two fine units over the last week. Next goal will be to try
and phase them with my MFJ-1026 to see if there is any pattern or null
shifting possible. In theory two parallel 600 foot Beverages even 65 feet
apart should allow some additional enhancement if fed properly.

Let me know what you think

73

Herb, KV4FZ

[Lee K7TJR]

Thanks Andrey you have confirmed my suspicions but.

Post by RA6LBS
And RF signals from Back direction of

reception is not "injected" at feed point, so direct multiplication of
attenuation by length does not play here.


It seems to me that All the signals from the back ( two transformer receiver end) direction come from
the reflection transformer and therefore travel the full length of the transmission line so I believe that
direct multiplication of the attenuation would be appropriate. If the signals are down 6 dB in 300 feet would
not they be down 12dB in 600 feet? Signals from the front (reflection transformer end)) however do not
use the transmission line except as a termination resistor. Perhaps because of reality versus theory in
actual practice you only see 9 dB, I dont know? Wonder what it is on 80 meters?
Am I missing something here? Perhaps you meant RF signals from the front, signals from the direction
of the reflection transformer end which would be true.
I know that Beverages with this wire work OK and are useful for many, however at my location I have
a Bidirectional (1Kft) with the reverse direction toward JA. It is made from aluminum fence wire with fairly low loss.
At times here in the early a.m. this antenna drops clear into the noise floor of the receiver and its low noise
preamp. I have verified this with other types of antennas. It is so quiet in that direction (over the Cascade
mountain range and then Pacific ocean) that I often hear the Hyperfix low power navigation system in the
Bering sea UA0 area. So my thoughts are to use caution if you are attempting a low noise direction with a
longer antenna of this material as it depends on the noise floor of the QTH as you have pointed out.
You may never know just how quiet your QTH is if you dont try something better. It seems to me you cannot
verify that your antenna is above the noise floor just by connecting it to the RX with all the losses involved.
What ever way you look at it there is a lot of loss in the reverse direction! About 2 dB per100 feet as I see it.
I still wonder about the incorrect termination effects due to losses and its affect on the RDF/pattern.
It seems to me we all wait for that magic moment when it gets really quiet and we hear the one DX call we never
thought we would hear. To me, I dont want to give away 5 to 10 or more dB of my system noise figure when I dont
have to because I wait for that very magic moment every day! YMMV

Lee K7TJR Oregon

[RA6LBS]

Lee, sorry for the late reply, I've been traveling.

And RF signals from Back direction of reception is not "injected" at
feed point, so direct multiplication of attenuation by length does not play here.

It seems to me that All the signals from the back ( two transformer
receiver end) direction come from the reflection transformer and
therefore travel the full length of the transmission line

Indeed, the signals reflected FROM the reflection transformer (
that`s the single transformer end ) is traveling along the
transmission line and DECREASED by its attenuation.

BUT! how and where from, those signals (which we call reverse direction
signals) are created? As I sad, "injected" from "nowhere" at two
transformers end (via transformer?) and coming along the same
transmission line (with its attenuation
again) in the direction of a reflection transformers?
To be twice the lines length attenuated in the last?

NO.

This is a common mistake I can hear often and my point was to clear it.
Sorry if I didnt made it clear in the first post.

Simplifying a lot, the wire is "illuminated" by radio waves from reverse
direction at its length and that means that some "drops" of a signal
is coming along its full length and some of them not the full one
before they reach the reflection transformer!

And that`s the only way explaining LESS, not the "double" (lines length
* db/ft * 2) attenuation I can observe here at my QTH and in a
number of installation and reports from other users of this type of
antenna.

Of course that observation are not on a 1db accuracy. But its quite
obvious and repeatable, that the reverse direction signals are less
then twice the line`s length attenuation down.

At times here in the early a.m. this antenna drops clear into the
noise floor of the receiver and its low noise
preamp.

Your are lucky one! my noise level from Hydro Power Station (less then
5 km away in a US direction) and a Nuclear Power station (less then
20 km away in JA direction) is around S4 at BEST times ... and the
city by it self ...

One can make ANY, even PERFECT directional antenna but if its
direction is to the noise SOURCE, than its usefulness is limited by
the noise source level only ...

It seems to me you cannot verify that your antenna is above the
noise floor just by connecting it to the RX with all the losses
involved.

But in assumption that there is no common mode ingress what else can
increase the matched input RX noise? And if the noise did increased,
if its sounds as a normal band noise from that direction (and it is
different at different times of the day and directions!) at that time
and carrying also some signals sky waves propagated?

I still wonder about the incorrect termination effects due to
losses and its affect on the RDF/pattern.

I have no hope that someone will repeat last century work
by Litva and others investigating the Beverage antenna with
helicopters for real life pattern measurements.

The A/B test I have made here, at moderate length up to 700 feet
clearly shows for me they are the same.

Much more disturbing factors are local noise and common mode problems.

[Lee K7TJR]

Thanks Andrey for your insights on one of Top-Bands favorite toys The Beverage
antenna. I think we agree on almost all points.

Post by RA6LBS
Indeed, the signals reflected FROM the reflection transformer (
that`s the single transformer end ) is traveling along the
transmission line and DECREASED by its attenuation.

I certainly agree.

Post by RA6LBS
BUT! how and where from, those signals (which we call reverse direction
signals) are created? As I sad, "injected" from "nowhere" at two
transformers end (via transformer?) and coming along the same
transmission line (with its attenuation
again) in the direction of a reflection transformers?
To be twice the lines length attenuated in the last?
NO.
This is a common mistake I can hear often and my point was to clear it.
.Sorry if I didnt made it clear in the first post.

I certainly agree.

I did not mean to imply that the signal ever travelled twice but that your statement
of the attenuation level below confused me.

Post by RA6LBS
The value of attenuation in a transmition line mode depends on
the insulation material used by manufacture but seems to
be near the same around the world and equals around 6 db per 300 feet
at 1,8 mhz.
Signals from the back direction will be around 9 db down from the
forward direction at 600 feet.

To my way of thinking an attenuation of 6 dB in 300 feet of line would be
12 dB in 600 feet not 9. I must have missed your meaning in the above words.

Post by RA6LBS
Your are lucky one! my noise level from Hydro Power Station (less then
5 km away in a US direction) and a Nuclear Power station (less then
20 km away in JA direction) is around S4 at BEST times ... and the
city by it self ...

Yes, I feel very lucky as there is 4 hydropower Dams within15 miles of QTH.
One as close as 2 miles. Fortunately they are at the bottom of a deep canyon that
shades me from their affects as near as I can tell. And, my city has only 1300
people and no stoplights. Lucky indeed.

Post by RA6LBS
But in assumption that there is no common mode ingress what else can
increase the matched input RX noise? And if the noise did increased,
if its sounds as a normal band noise from that direction (and it is
different at different times of the day and directions!) at that time
and carrying also some signals sky waves propagated?

Agreed, at the time I made that statement I was trying to carefully evaluate the
impedances reflected by the lossy line made of the WD-1A. I was misled by an
error in the calculation of the impedances that led me to believe there was a huge
mismatch. There is not, so you are quite correct. I was wrong.
The reason I was looking for the impedances was I wanted to apply them back as a
load resistor for the Eznec Beverage model. As it turns out there is very little change in
line impedance (and Beverage load) as a result of the high attenuation so the Eznec
model shows very little change in the pattern from forward to reverse as you have observed.
My friend K7FIL has agreed to fly his airplane around my antenna farm in a GPS
guided circle with a small TX. I really hope to get at least one pattern to share on several
types of RX antennas. Hopefully more.
Lee K7TJR Oregon