What Is a Beverage
antenna?
The Beverage
antenna is simply a straight wire, usually several hundred feet long
and about
8 feet high. It is a VERY
effective antenna that will enable you to hear extremely
weak DX signals that are buried in noise or covered up by other
interference. It was invented and patented
many years ago by Dr.
Harold H. Beverage, who worked for RCA.
Mine
are "magic" antennas! On a scale of one to ten, the "wow factor" is an
11.
Why would you want one?
Because
you will hear LOTS of weaker signals that you won't
hear on your vertical, inverted-L, dipole, or most other antennas; not
to
mention a worthwhile reduction of unwanted signals and noise from
undesired directions. The S/N (signal-to-noise) ratio of a Beverage is
far superior to any vertical, dipole, or loop, as well as most compact
receive-only antennas.
If
you have the space, you should consider at least one Beverage
antenna, even just a simple single-wire Beverage. (If not, there are alternatives to a
full-size Beverage.)
Even a short
Beverage antenna is better than no Beverage! Although
Beverages
are typically at least one wavelength long on the lowest band, even a
half-wave (or even shorter) Beverage antenna can very often out-hear
any vertical,
dipole, or loop.
The Ultimate SWL Antenna.
The Beverage antenna is the
ultimate SWL (Short Wave Listener) antenna.
Period. They are not just for amateur radio operators.
Or do you like
crystal radios? You haven't lived until you've connected
your crystal radio to a Beverage antenna. (And no, it's NOT cheating to do
that! :-)
|
Beverages are extremely
broadband antennas.
Beverage antennas do not
require re-tuning to QSY or switch bands, because they are
non-resonant. The design we use covers 100 KHz to 30 MHz without
retuning a thing or even having to adjust the signal level.
The 580' bi-directional Beverages we made from electric fence wire work
absolutely
fantastic for receiving weak DX signals on 160 meters, but they also
work extremely well on 80, 60, and 40 meters, and often on 30 and 20
meters (and rarely, even up to 10 meters) as well. On any HF band, we
rarely listen on
the dipole or vertical antenna that we're transmitting on, except to
see how
much
better we can hear on the Beverages antennas.
We sometimes play with them on the AM broadcast band. Even during
the daytime, there are very few frequencies where we cannot listen to
at least one radio station. And on some frequencies, we
can select up to four
different AM stations on the same frequency as we switch among
four different directions.
Recently, we've been listening on VLF, down
as low as 150 kHz, to Foreign
AM broadcast stations. |
Are They Hard to put up?
No. It has been
said
that Beverage antennas "want to work". In other words, their
construction is not critical. If they are not exactly in a straight
line, or if their height varies a little (such as if you have to cross
a ravine, or go up and down a hill — even a steep hill —
they will
still work great. They can even be run through a thick woods, using
trees as
supports, without affecting their operation.
And neither do they cost
hundreds of dollars.
A Simple,
Single-Wire Beverage antenna
All you
really
need for a simple Beverage receiving antenna is a long single wire, 6
to 10 feet high, between one-half and one wavelength long (or more, up
to a point) at the
lowest desired frequency. The far end should be pointed more or less in
the direction you
want to receive signals from. (For example, you
might try a Beverage
pointed NE towards Europe.)
You'll
need coax
(almost any old coax) feeding the near end, a simple matching
transformer, a
termination resistor at the far end —pointed in the desired
direction— and grounds at both ends, like the diagram above. Much
of the information on this page that applies to bi-directional
Beverages also applies to a one wire Beverage antenna.
The
WØBTU Reversible-Direction Beverage
antennas
I have two
2-wire, switchable bi-directional Beverage receiving antennas. Both are
580' long and are supported on 10' high posts 100' apart.
Some
photos are here. NOTE: Those photos need
updating; the present Beverage antenna transformers at
WØBTU use the
Amidon
BN-73-202 ferrite cores as shown below.
We (W0BTU and XYL
KD0LAJ) built them for
160 meters, but they work well from VLF (well below the low end of the
AM broadcast band)
to 20 meters or more.
Looking from the
air, our Beverages cross like an X, covering:
- NE
(Europe, N. Africa)
- SE
(S. America, Caribbean, S. Africa)
- SW
(Australia and Oceania)
- NW
(Japan, AK).
- Aerial
photo
We can turn a
knob (photo
below) and
instantly select any of those
four
directions that we
want to listen towards.
BACK TO TOP
There Is More Than One Way to
build a 2-wire Beverage antenna.
There are
different ways to make bi-directional (switchable direction) Beverage antennas. Here are what
I think are the best ways:
- One
Beverage
here (SE-NW) has the direction and termination switching arrangement
using a
remote relay (at
the Beverage antenna's feedpoint) to switch directions with a single
run of coax.
- The
other Beverage here (NE-SW) has no remote relays; instead, there are
two runs
of
coax
running all the way from the antenna to the operating position; and the
direction switching relays and
terminating resistors are there.
Neither method
requires a separate control cable to switch directions. The 12 volts DC
direction switching voltage is sent up the same coax that the received
signal comes down. This only requires two .1 uF disc ceramic blocking
capacitors and two RF chokes, which are made from approximately 7 turns
of #26 magnet wire through an Amidon FB-73-801 ferrite bead. (We use Belden®
heavy-armored Polythermaleze®
insulated wire for these chokes to prevent shorted turns, as there is
no room for a protective liner inside this bead and these cores are
conductive.)
We have had a
number of requests for schematic diagrams of our reversible Beverage
antennas. Here are diagrams for both types.
- The
feedpoint box schematic for our NE-SW Beverage is similar to the one
in ON4UN's book which uses two coax feedlines (show to the right).
.
- Control Panel Schematic
for both W0BTU two-wire
Beverage antennas
- Below is
the schematic of the remote feedpoint box on our SE-NW Beverage, which
uses a single coax feedline (click to zoom).
NOT SHOWN ABOVE: GDT added between coax shield and ground.
Protects K1, RFCs, T2, etc. from lightning surge current on coax
shield.
How do two-wire reversible direction Beverages work? Greg, ZL3IX has written an excellent
explanation:
(4.7 MB files)
EZNEC plots @ 1.83 MHz - W0BTU 580'
Bi-directional Beverage antennas
How Far Apart
should the Beverage antenna
wires be?
There is
no need to use wide spacing between the two wires in any
bi-directional Beverage antenna! Some people still use 6" or even 12"
wide
spacings. Don't. That wide
spacing makes no electrical sense at all, and is subject to imbalance
from nearby objects. One-inch (approx.) spaced 450 ohm
window (ladder) line works most of the time,
if you don't want to make your own
ladder line like we did.
When
deciding how far apart AND how high we are going to make our Beverage,
we need to keep the following important point in mind:
For two-wire reversible Beverage antennas, the line impedance
(of the open-wire line)
should equal the antenna impedance
(between the line and ground, also called the common mode impedance).
We
used
"galvanized" (probably plated with cadmium rather than zinc) steel
electric fence wire labeled "17 gauge", and
calculated the diameter (.061") vs.
spacing (1.10") so that the line impedance was equal to the
antenna impedance at 10' high. If you construct
your Beverage so that those two impedances are significantly different,
then you need to change the impedance ratios of the matching
transformers.
For example, if we use
145 ohm line (surplus twisted pair telephone line), which at 6
feet above ground has
a common mode (both wires to ground) impedance of about 480 ohms, then
we
would need to change the 1:1 transformer to about 3.33 to 1 for optimum
performance (F/B ratio) of our Beverage. (The required ratio of other
transformers would change also.)
However, since we want to use matching transformers with binocular
cores (due to their superiority over toroids or beads), using other
than 1:1 line-to-antenna Z ratios can present some challenges.
- Practical
Z ratios are somewhat limited. Chart of turns ratios (PDF)
- Some
impedance ratios require so many turns that winding them can present
winding challenges (too many wires to fit inside the core). This also
can add unwanted inter-winding capacitance.
- In
transformers where balance is important, we should have an even number
of turns on the center-tapped winding. Sometimes, with certain Z
ratios, trying to accomplish that also requires many more turns.
- Using
half-turns (to try and obtain a certain Z ratio) are usually a no-no;
that can cause significant losses.
Before we
just put up any old pair of wires, then, we need to make sure that we
can make a good set of matching transformers without these issues
cropping up later.
Calculating
Impedances vs. Dimensions Is Easy
- Line
impedance: The impedance of the open-wire line that the bi-directional
Beverage antenna is made of. This depends mainly on two things:
- The diameter of the wires
- The spacing between the wires
- Antenna
impedance: the impedance of both those wires to ground. This depends mainly on
three things:
- The diameter of the wires
- The spacing between the wires
- The distance from the wires to the earth.
Here's some
spreadsheets that you
might find useful for
calculating these impedances, in Excel or Open Document (Open Office)
format. They
were
invaluable to me in designing the open wire line for my Beverage
receiving antennas, so that I could use 1:1 reflection transformers.
They also take into account whatever dielectric is between the wires,
air or plastic. You can
open the .ods file with the free Open Office spreadsheet.
We fabricated
our
own open wire line out of plated steel electric fence wire, which is
very strong. Using the known
values of
(1) The wire diameter (.061") and
(2) The desired height above ground (10'), I then used a spreadsheet above to calculate the
spacing at which the antenna impedance equaled the line impedance (1.10").
I then made some plastic spacers
with
two ~.066" diameter holes 1.10" apart; this spacing made the common
mode and
differential mode (line) impedances nearly equal (about 410 ohms).
Headless nails
driven into a small piece of wood, clamped to a drill press table,
makes easy work of drilling many spacers. When drilling the second
hole, place the first hole onto a nail nearly the same size as the
holes.
Impedance Equation page
What Materials to
use for the Beverage
antenna?
They can be made
from almost any conductor, be it copper, steel*,
aluminum, 450 or 300 ohm ladder (window) line,
twisted-pair
line, and
even coax.
*If using magnetic steel, it should be
plated with a non-magnetic material of sufficient thickness.
A major
consideration is strength, and that's only one of the reasons we use
plated steel electric fence wire. We have
animals
(deer) and falling tree limbs. The galvanized electric fence wire, 10'
high,
has never broken even when a very heavy limb fell from the top of a
tree onto the end of one of them. Take a look at these photos, and
you'll understand:
Photo 1 | Photo 2 | Photo 3 | Photo 4 | More photos
That branch weighed several hundred pounds (and it was coated with
thick ice) and fell all the way from near the top of the tree, where
the Beverage broke its fall. No 450 ohm line ladder line
would have held up like that!
Earl
Cunningham,
K6SE (SK) swore by galvanized electric fence wire for Beverage
antennas.
He said copper was inferior, it did not produce as good a F/B ratio. (I
agree, but we never obtained the 60 dB F/B ratio on sky wave signals
that Earl claimed.) Reason being, the signal from the feed end has to
travel
the length of the antenna twice, further attenuating the unwanted
signal. Earl
once put up copper, but took it down and replaced with with galvanized
electric fence wire. Sometimes losses are an advantage. Lossy
wire also makes the termination less critical.
I've
recently read where someone complained that their electric fence wire
rusted rather quickly. But I (and many other satisfied users) have
never experienced that. Not with any brand I ever purchased, made in
the USA.
There is NO need
to use insulated wires for a
Beverage antenna, unless you are using a BOG (where the antenna
is actually touching the earth or the wet vegetation just above it).
It is
not recommended to make a transmitting antenna out
of lossy, high permeability steel wire.
What
about Window Line?
You could
use ready-made insulated 450 ohm window ladder line (the kind with the
rectangular holes punched between the wires every so often) and save
yourself the trouble of making your own open-wire line for your
Beverage antennas. Lots of hams do.
However, some potential problems to consider with window
line:
- It has a lot more wind load and might flop around and break in
the wind, especially if it's too loose. Twisting it might help. Ask
someone who uses it for their long Beverages (we don't).
- The line impedance changes a lot when it's wet, icy, or
even covered with snow. (Covered with enough ice, the line impedance
could drop well below 100 ohms!) That
can severely affect the pattern and front-to-back ratio of your
Beverage.
The so-called
"450 ohm" brown insulated window line I have here is actually about 420
ohms dry (which is OK).
How High
should a Beverage antenna be?
Although they
can be lower and still work just fine, they should be
high enough to walk under. Mine are 10' high, which is about the
maximum height for a Beverage if you want to use it on the higher
bands. Unlike transmitting antennas, higher is
not better, but rather, worse.
There's a rumor
that there is somehow a benefit to sloping the ends down to the earth
gradually in,
say, the last 60 feet at each end. (The reasoning was that the vertical
drop
at each end might pick up unwanted signals off the side). Don't do it. That adversely affects
the antenna's impedance and could actually hurt performance. And
besides, it's a safety hazard.
"There
really isn't a logical reason to slope the ends of a
Beverage. After
all, six feet of vertical drop is six feet, no matter if the drop is
over 50
feet or straight vertical." --W8JI
How
Long
should a Beverage antenna be?
Typically,
they are
made about one wavelength long. But even a short Beverage is better
than no Beverage. Although Beverages
are typically at least one wavelength long on the lowest band, even a
half-wave (or even shorter) Beverage can very often out-hear any wire,
vertical, or
dipole you
might be using. For example, if you only have room for a 200' - 250'
Beverage on 160 meters, it may well surprise you what it can do for you.
I
chose 580' because it is about one wavelength on 160 meters, my primary
band of interest. That length gives a 3 dB beamwidth of almost 90
degrees. Therefore, the entire 360 degrees of the compass is covered in
just four directions.
If you are only interested in covering certain areas of the world, you
should think about making them longer, as that will narrow the
beamwidth.
It has been said
that it is a waste of
time and counterproductive to make your 160 meter Beverage longer than
two
wavelengths long (over 1160' on 160 meters). That may very well be true
in most locations. But that really depends on the ground conductivity.
K5RX reports that with his exceptional ground conductivity, his
three-wavelength-long Beverage is the best one he has. And he has plans
to extend it another 300' soon to 2100'. (Jim reports that just one
ground rod at K5RX measures about 10 to 15 ohms resistance.)
I use them on 80, 60, 40, and 20 meters --where they are very long in
terms
of wavelengths-- and they work VERY well there, even though our ground
conductivity is likely not as good as K5RX's.
Just keep in mind that the longer the Beverage, the narrower the
beamwidth!
Beverage
Antenna Transformers
We cannot just
connect our coax directly to a Beverage antenna. A transformer is
required for the following reasons:
- In either single-
or bi-directional Beverages, to match the low impedance of the coax to
the high impedance of the Beverage antenna
- In
bi-directional Beverages, a reflection transformer is
required to receive signals off the feed end.
A second feedpoint
transformer is also required to receive the push-pull signal from the
opposite end, sent down the antenna from the reflection transformer.
- To isolate the feedline from the antenna, in order to
avoid common-mode pickup of unwanted signals and noise on the coax
shield.
The transformers are
the most
critical component in any Beverage antenna design, especially
bi-directional Beverages. You see a lot of
different Beverage antenna transformer designs in different books,
magazine articles, and all over the Internet, and the main goal of
writing this page was to clear the dust and get to the meat of good
Beverage
transformer design. They are not
difficult at all to make. Here's how.
A Beverage antenna
feedpoint transformer MUST have separate windings (as opposed to an
autotransformer) to
prevent reception of undesired common-mode signals and noise.
We wind them with different colors of #24 or #26
gauge magnet wire, which makes
it easier to tell which windings are which after they are wound through
the core.
For a 6.25:1
impedance ratio Beverage antenna transformer, using the core below:
Primary (Hi-Z Bev.): Five turns brown #26 magnet wire
Secondary (75 ohms): Two turns green #26 magnet wire
If you use 50
ohm coax, then make a 9:1 transformer by using six turns on
the primary instead of five.
Note that one turn is through both holes
as shown in the photo.
There
are a number of popular Beverage antenna transformer designs floating
around, some of which are so
lossy that they need a preamp to hear the weakest signals. I used to
make them from
stacks of Amidon FB-73-801
ferrite
beads. However, we now use Fair-Rite 2873000202 (Amidon BN-73-202) ferrite binocular
balun cores, which are
far superior and much easier
to make. They seem so small (only 9/16" long), but do they
ever work! This binocular core
design provides significantly lower loss, greater bandwidth, and
freedom from core saturation than any
toroids or beads will. Normally, a preamp is NOT needed.
Shown to the left is a 2873000202 / BN-73-202 binocular core with a
special liner that we use, ready for winding and labeling. Among other
advantages, the irradiated polyolefin HST liner protects the
magnet wire from touching the conductive core, abrading the
insulation, and degrading the performance of the Beverage antenna.
Reflection
Transformers
If you erect a
bi-directional Beverage, just make sure you use a
reflection transformer like T5a in
the schematic
from ON4UN's book.
That's exactly the
way mine are wired, and they work great.
Forget about the skimpy design
that grounds only one wire, but leaves the other wire floating!
That
inferior arrangement may work sometimes (depending on the length of the
wires and
the frequency you happen to be listening on), but a reflection
transformer is so simple to make. You have to make two anyway (at the
feedpoint); why not a third one at the far end? You will see a better
front-to-back ratio using a reflection transformer.
On the reflection
transformer (and sometimes on another feedpoint transformer), one
winding uses two pieces of magnet wire, twisted together as shown.
(Note that they're slightly different colors). The twisted bifilar
winding helps ensure that the signal levels are not unbalanced (very
important on a two-wire Beverage antenna).
1:1
Beverage transformer after winding. This can be made into either a 1:1
center-tapped feedpoint transformer or a 1:1 reflection transformer.
- Secondary:
4 turns #26 green
- Primary:
2 turns #26 twisted bifilar-wound (total 4 turns).
|
This is a 1:1
reflection transformer that we
make and use, per N1EU's
design info. One winding is made from two bifilar turns
of
#26 twisted pair, and the other winding is four turns of green #26
magnet
wire.
The green wire is connected to ground,
and the other two wires
connect to the Beverage antenna.
|
Click photos for
larger image
The
control box to the left —containing the Beverage antenna matching
transformers, relay, etc.— is the newest one, and it's currently
installed
on my SE-NW Beverage antenna. (Click to zoom.) This design turned out
to be the best one we ever made. It has better sensitivity and F/B
ratio of any single-coax Beverage antenna switch box that I have ever
made. (That could be because of a different termination resistor value.)
I have received many inquiries over the years about these enclosures
from
both amateur radio operators and antenna manufacturers. This one is a
Hammond NEMA 4
watertight enclosure, P/N 1554D2GYCL (clear lid), 4.7"L x 2.6"W x
2.4"H.
The one below and on the right is Hammond P/N 1554D2GYSL (smoked lid,
same dimensions).
Both are polycarbonate, completely waterproof, UV resistant, have
gasketed lids with 2-piece tongue-and-groove construction, and are
designed for outdoor applications. The one with the clear lid can be
obtained from Mouser, and the one with the clear smoke lid can be
purchased from Newark. (In units exposed to the
sun, the temperature inside the enclosures would likely be lower with
the smoked lid. Suit yourself.)
Since we use non-hermetically-sealed direction switching relays
(because
we need bifurcated/paralleled heavy-duty contacts and grounded frames
for maximum reliability),
it's very
important to keep out moisture! We once had a relay freeze up in the
winter, from condensation in an enclosure that was not sealed like
these are.
The secret to
keeping moisture out includes properly filling all the
connectors
with non-hardening, clear silicone dielectric compound. As the weather
changes, that compound moves in and out of the connectors like a
piston, providing a near-perfect hermetic seal that prevents the humid
air outside from mixing with
the dry air inside the enclosure.
We
do NOT use vents, like some people incorrectly insist on. There has been no
evidence of moisture ingress (such as condensation on the clear covers)
whatsoever.
I also have some smaller Hammond 1554B2GYCL enclosures for the
reflection transformers. However, there is nothing about the reflection
transformers that would be harmed by moisture ingress, so
I usually just use prescription pill bottles or other types of
enclosures without a hermetic seal.
Some components inside:
- 1:1 and
6.25:1 transformers (shown above) with isolated windings.
- Heavy-duty
ceramic Bourns 90 volt Gas Discharge Tubes (between each wire to
ground, and between the coax shield and ground) to help protect the
components from getting damaged from nearby lightning strikes. We have
not lost a transformer (or any other component) since we began using
these. (Because
of these, we could probably use a much lighter-duty termination
resistor
than we do.)
- 33K drain
resistors to greatly extend the life of the GDTs.
- 4PDT
P&B/Tyco relay. The coil has a .1
uf
capacitor and a low voltage MOV in parallel with it. The contacts that
select the direction are paralleled for increased reliability, since we
are switching a dry circuit. This relay was also chosen because it is
possible to ground the frame (which we do).
- Single
470 ohm Ohmite Type OY non-inductive termination resistor, paralleled
with another resistor to obtain the proper value of termination
resistance.
- Bright
green clear LED connected to one of the relay contacts, so
that we
can see if the relay closes from a distance. It can be seen from
several hundred feet away at night (it's so bright, it's like a green
laser with less than 6 mA of current!). I added it because after
lightning
blew out my old transformers (before I added the lightning protection),
I thought I had a bad feedline connection somewhere (I did; I got a bad
batch of F connectors). And it came in
handy when I first put it into operation.
NOTE:
The solder lug on the coax F connector is NOT grounded! It was simply
used in lieu of a flat washer. Any coax shield ground must be kept
separate from the antenna ground for common-mode isolation.
The control box to
the right is for my NE-SW Beverage. (Click to zoom.)
Since there are two runs of coax feeding it, it's much simpler than
the one above. The switching and termination take place in the control
panel next to the radios,
rather than remotely. It contains:
- Two 6.25:1
transformers:
- One
balun, center-tapped
- One unun
- Heavy-duty
ceramic gas discharge tubes (GDTs) to protect the transformers
from nearby lightning strikes.
Those two extra
black tip jacks were for grounding the Beverage antenna
in
advance of a thunderstorm. Since adding the GDTs, I no longer use them;
I just leave the antenna plugged into the control box all the time.
There are also GDTs in the reflection transformers for lightning
protection, as well.
See the
following links for other information on the general design of the
transformers we use. More info on building good Beverage transformers
is here:
Terminating
Resistors
Although a
terminating resistor is optional on a single-wire Beverage,
it is highly
recommended
unless you need to receive off both ends at once. Adding the resistor
will greatly reduce noise and QRM from unwanted directions.
A 470 ohm
resistor will
usually do
just fine. For a single-wire Beverage, you can subtract the ground
resistance from the required value.
We use Ohmite
type OY metal composition resistors,
470 or 75 ohms, 2 watts. They are FAR more
rugged than others for withstanding destructive surges caused by
lightning strikes (either cloud-to-cloud or ground-to-cloud strokes) in
the vicinity. Mouser Electronics # 588-OY-470-E,
only $1.20 each. (If you enjoy having to replace blown termination
resistors, then use something else. :-)
What About the
Grounds at each end?
Normally,
a few short (~50')
ground radials and a couple of ground rods at each end of the Beverage
have proven to be
effective. Works for me and lots
of other happy Beverage antenna owners.
Check out W8JI's number of radials and ground rods vs. ground
resistance measurements.
Just keep in
mind that if you are using a bi-directional Beverage and it doesn't
seem to hear well off the feed end, then you may need to improve the
ground at the far end (at the reflection transformer). When I put up my
first 2-wire bi-directional Beverage (with different transformers than
I use now), I occasionally had to 'help' the ground conductivity at the
reflection transformer end. Although there were two copper ground rods
and three radials, the only thing that made it work right when
receiving signals from the feed
end direction was to pour a hot, very concentrated solution of
magnesium sulfate
(Epsom salts) around the ground rods. (The ground was frozen at the
time.) The Beverage antenna's
reflection transformer ground is more critical. For a
single-wire Beverage, the ground at the end is not as critical.
That's no longer
necessary, as I've added more radials and the ground rod conductivity
has improved after a few months. But if you have a problem with very
weak reception off the feed end of your two-wire Beverage, it would be
cheap and easy
for you to try. Epsom salts are available at about any drug store or
grocery store.
Note that the signal strength off the
feed end of a bi-directional Beverage can be weaker. That's normal, and
a non-problem.
- The feed
ends (where the coax connects) of my Beverages have two ground rods and
three or four 50' long surface ground radials.
- The far
ends (reflection transformer ends) have two ground rods and up to seven
50' long surface ground radials. NOTE: You should avoid running radials
directly underneath your Beverage antenna.
One ham had a
problem with the rock being very close to the surface, and wondered
whether cut-off ground rods driven in at an angle would help. If that
is your situation, consider a ground
screen at the ends (or more radials) as opposed to relying on
shortened ground rods.
We do NOT ground
the coax shields at the Beverage reflection transformer box, nor do we
switch them. The only thing you want to ground at the feed end of your
Beverages is the transformer winding connected to the Beverage.
Ground rods: I use 5/8" x 8'
copper-clad steel ground rods. However, if the soil
here in this part of SW Missouri weren't so full of rocks, I would use
1" copper water pipe instead because it's a lower resistance ground.
Which Coax to
feed your Beverage
antenna with?
I use 75
ohm,
flooded Commscope® quad-shield RG-6 coaxial cable. (The
shield is four layers of aluminum: braid-foil-braid-foil; the inner
foil bonded to the dielectric). It was
designed for CATV use, and because the CATV industry uses so much of
it, 1000' spools of it can be obtained very inexpensively!
Beside
the low cost, it
also has other advantages. "Flooded" means that there is a sticky
substance permeating the shield. That sticky stuff is there for the
purpose of keeping out water if the coax should get cut, nicked or
nibbled on by little animals. It only takes one little invisible cut to
let water soak the shield for some distance on either side of the cut.
Corrosion of the braid will follow in short order.
If water gets inside non-flooded coax, this will not only increase
loss,
but worse, can cause noise! The noise can sound like static, and can
keep your Beverage antenna from working like it should.
The RG-6 coax
feeding my Beverage antennas runs along a fence in the
grass for almost 600'. I don't require ferrite chokes to prevent
unwanted signal pickup. The coax shield is grounded ONLY at the station
end, NOT at the antenna.
Crimp-type
"F"
coax connectors with o-ring seals are fine. You don't need BNC,
N, or UHF (which
are
not waterproof) connectors.
To keep water out, fill them with clear
silicone dielectric compound before assembly. Home Depot and DX
Engineering sell the good snap-on F connectors.
If there's no room
for a Beverage antenna
For receiving, a
Beverage is simple and easy and very good. If you do not have the room
for even a very short Beverage, there are a number of alternative
receiving antennas. Look
at the Slinky Beverage, BOG, K6SE's Terminated Delta Loop (KAZ),
Waller Flag,
K9AY,
Flag, EWE
, or Loop
antennas. The Waller Flag has the pattern of a
one-wavelength-long
Beverage and can be even mounted on a tower and rotated. It requires
cascaded, antenna-mounted preamps and careful attention to minimizing
unwanted common mode signals.
I have very little experience with any of these; Google is your
friend.
Even better than
those is an array of loops or phased short verticals. An array of
short verticals arranged in a circle is maybe even better than
Beverages, but they are much more complex.
Having said
that...
More
than one person has e-mailed me privately and stated in no uncertain
terms that their Beverage antennas were definitely superior to their
circular array of short verticals. Others on public pages we've seen
say just the opposite. In any case, either one is usually superior to a
vertical or dipole.
Some people have had good success with loaded or Slinky Beverages. I
have no
experience with them, but I'd sure like to try a short Slinky.
http://www.w8ji.com/slinky_and_loaded_beverages.htm
"No room for a traditional Beverage? Then try a Slinky. I had 5 of the
large ones in series over 150' for almost 20 years and it was a solid
performer; very quiet likely due to the steel wire loss and a preamp
was used. At that time it was my only option for due East/SE where a
lot of good DX comes from and I worked a lot that locals couldn't hear,
rear rejection was excellent. A K9AY wasn't even close." --KM1H
The BOG:
Beverage On the Ground
The very first Beverage antenna made by Dr. Harold H. Beverage himself
was
in fact a BOG. The Beverage On the Ground is
described in ON4UN's Low Band Dxing
4th edition. I'm convinced that they can work very well on some bands,
based on a
number of experiences that we've read on the Topband
reflector and feedback from our customers.
Recent
tests by other hams using even short (approx. 140' long)
BOGs show they can often significantly improve the S/N ratio on 40, 80,
160, and the AM broadcast band —as
compared to an inverted-L with a good ground radial system— by
greatly reducing local RFI from
power line noise, etc.
The impedance, velocity factor, and signal levels are a lower than
a Beverage antenna several feet in the air, depending on ground
conductivity. A very short BOG may possibly need a preamp. KM1H's experience
The lower
velocity factor has several effects, one of which is that a BOG can be
considerably shorter than an elevated Beverage.
Either a wire laying on the ground or made from coax (so-called 'snake
antenna', not a BOG),
there's a right way and a wrong way to build one. They can be made
either single- or bi-directional.
I once knew a
ham who, during a local thunderstorm one Field Day night, used a BOG
(or was it a piece of coax?) antenna to receive for 75 phone. He could
hear
little through the QRN on the dipole he was using, but the receiving
antenna on the
ground
really worked, according to him and others who were present.
You should bury BOG ground radials (if you use any), because they can pick up unwanted signals..
BOG matching transformers and
terminating resistors
Is it practical to
use a Beverage as a transmitting antenna?
Sometimes
it is! I had a lot of fun trying that, and could work many places
--even DX-- on the NE Beverage that I couldn't work on a 35' high
multiband dipole.
Check out this thread:
Carl,
KM1H kind of lit a fire under me when he said he successfully used his
Beverages to transmit. My own experiences on the different bands are
outlined there. (To summarize: with
100 watts on SSB, it worked awful on 160, a little better on 80, still
better on 40, and not bad at all on 20.)
This
is the little transformer I used for both receive and
transmit on my unterminated NE/SW
Beverage antenna. It handles 800 watts (on SSB) from 80-10 meters. I
even used it for a rather long AM QSO with 200
watts carrier. It's amazing how low-loss this tiny little transformer
is! Check out these
power vs. temperature tests
I performed on that transformer with 800w carrier, more than enough
time to tune up. The
temperature didn't rise to anywhere near the Curie temperature of the
core material (310 degrees F.)
I added a half-dozen radials between 25' and 50' long on the ground
at the feed end, and started getting unsolicited reports about how much
louder my signal was.
The signal from the Beverage is best to the NE USA and Europe, due
to its low angle. Closer in, signals are somewhat weaker. It's more of
a DX antenna.
What bands are
Beverage
antennas good for?
Basically, the non-resonant Beverage covers the entire radio
spectrum,
from VLF to the upper end of the HF (short wave) region. It is an extremely broadband
antenna.
They were first used on VLF and MW and first popularized for amateur
radio use on the 160 meter band. Still, they continue to be thought of
as an antenna that is really not of much use above 80 meters.
Not so. A recent poster on
the Topband reflector stated, "If you think they work good on 160, you
should try them on 40!"
This lit a fire under me to try them on 40 meters. He was
certainly right!
Here are the patterns
of my Beverage antennas @
7.15 MHz:
With the narrow
beamwidth of the main lobe and only four directions to choose from, I
expected to miss many stations outside
the main lobe. However, I was very pleasantly surprised, because in
practice, I can almost always hear better on the Beverages than I can
on my multiband dipole or 40 meter monoband ground plane. (I do wish I
had one pointed due
west, though; I think I would hear the USA west coast better on 80
meters and above.)
I did find a
"problem"
with using Beverages on most bands: when working stations with similar
antennas and power, I can hear the other guy very well; but since the
station at the other end of the QSO doesn't have a Beverage (or other
low-noise RX antenna), he
experiences the same QSB, etc. as I do when I listen to him on my
transmitting
antenna. (Hearing that well is a good problem to have. ;-)
But what really is the practical frequency range of Beverage antennas?
I recently got a private e-mail that in one rare instance,
his Beverage antenna outperformed his array of stacked Yagis on 10
meters! Don't
expect that, but they have been reported to work very well on 20 meters
on a number of occasions. They are almost always better than my dipole
on 20.
Here it is on 80
meters:
What about erecting Beverages near other objects, or near other
Beverage antennas?
Beverages
should
not be erected over metal fences. Why? A Beverage requires a poorly
conductive ground (poor compared to the wire itself) under it to work
right.
Having said
that, ZL3IX successfully built one above an apparently ungrounded metal
fence. He explains how he did it near the end of http://www.g3xrj.com/RxArray_files/2wire_bev/2wire_bev.htm.
If it can be avoided, don't run them parallel with other conductors
(metal fences, power lines) for long distances. Try and run them at an
angle to
avoid coupling to them.
Beverages,
being
non-resonant, usually do not readily interact with each other. This is
why we
can have cross-fire or end-fire Beverage antenna arrays, because the
antennas do not couple to each other to any significant degree. (Mine
cross at about 90 degrees to each other, are only
about 7 inches apart where they cross, and do NOT affect each other.)
Multiple
Beverages Using a Common Ground
Feeding more than one Beverage antenna from the same point using a
common ground is a bad idea. The reason is that signals from all of the
Beverages --not just the one you have selected to listen on-- pass
through that ground simultaneously. And since that ground has
resistance, there is a very real potential of sharing signals between
Beverages. If this happens, you might hear undesired signals (and
noise) from unwanted directions picked up by the other Beverage(s). The
front-to-back and/or the front-to-side ratio will seem degraded. The
higher the resistance of the ground, the more noticeable this effect
will be. Note the following references:
Different
Beverage Antennas from One Hub
Never run different Beverage antennas from a single spot, using a
single ground rod (or ground system). In such a case you will, via the
common ground rod resistance, cross-couple part of the signals from one
Beverage into another Beverage.
If
you want to run different Beverages from one point, run the master feed
line to a switching box (head end of the master feed line), and fan out
to various feed points, each of which is fed via a separate feed line,
in such a way that the ground rods of these feed points are separated
at least 5 meters from one another.
From the the ARRL's Low
Band DXing
by John Devoldere, ON4UN (5th edition) p. 7-76
|
Never bring multiple antennas to one feedpoint, especially when they
share one common ground. I've noticed a definite deterioration in
pattern with multiple feedpoints arranged with only ten feet of
spacing, even when they had separate ground systems. One set of
Beverages installed with 5-10 foot of feedpoint separation has
noticeably poorer patterns than other identical length antennas with
wide separation at the feedpoint.
|
Conclusion:
Never share grounds between antennas.
If you really need to feed more than one Beverage from a single
location or hub, then you should make provisions to remotely disconnect
and properly terminate the unused antennas.
Misc. Beverage
antenna notes and information
What Direction to point our Beverage
antennas?
If you are located in
the USA, DON'T orient your Beverages either due North, South, West, or
East unless you have a very good
reason to! They should point either Northeast,
Northwest, Southwest, or Southeast. Here's why.
If you look at
an azimuthal map (or use
software like DX
Atlas) from most
locations in the USA, you'll see that
—generally speaking— Beverage antennas pointing due East,
West,
North, or South are NOT pointing in the optimum direction!
- North is over the poles, and any aurora (which occurs much of the
time) destroys propagation in that direction.
- There's usually not much to hear when we point either due South
or due North.
- EXCEPTION: If you live in an area of the US
where there is a high population density both north and south of you,
such as near the coasts. A North/South bi-directional Beverage might
then be quite
useful, especially if you are not that interested in working DX.
- Almost all of Europe (and a portion of N. Africa) is Northeast, NOT East!
- Australia, New Zealand, Mexico, Central America, and most of
Oceania is Southwest, not West.
- Japan and Alaska is Northwest,
and NOT West.
- Most of the Caribbean and South America is Southeast, not South.
- Africa —depending on the country you want— varies all
the way from Northeast, through East, to Southeast.
For working
stations in the USA, orienting your Beverage antennas NE-SW and SE-NW
has the following advantages for reducing QRM:
- Pointing NE nulls out the southern coastal states such as Florida.
- Pointing SE nulls out the northern coastal states such as New
England, New York, as well as eastern Canada.
- Pointing SW nulls out Oregon, Washington, western Canada, etc.
- Pointing NW nulls out California, Arizona, etc.
If you DO need
to point N, E, S, or W, perhaps the best thing to do is erect a
separate Beverage —perhaps a single-wire one— in addition to your NE-SW and SE-NW
Beverages. An azimuthal projection map centered on
your QTH will tell you where you need to point your Beverage
antennas.
How to tension
the two wires equally:
- Only three pulleys are required to tension both wires equally by
pulling on a single rope.
- This arrangement gives a necessary 1:2 mechanical advantage, if
one man is to tension this antenna sufficiently.
Q: What are the
negatives of the 2 wire vs individual single ones?
A: The
negatives?
I think
the
positives outweigh any perceived "negatives"! The "negative" is all
about the single wire design, because you're restricting yourself. With
two wires instead of just one, you
could switch between both directions, using the same supports! For
2-wire
Beverages, only
half the
required amount of supports and real estate are required to cover both
directions. Complexity (that
could be argued against) and perhaps cost. And some types of
open-wire line might not last as long as a single wire, depending on
what you use. That's about
it. The two-wire Beverage does not have a degraded pattern or F/B ratio.
A two-wire
Beverage, like this one allows operation in either direction.
On mine, there's
a relay, one or two termination resistors, an RF choke, and a capacitor
at the
feed end, besides the two transformers. Putting +12VDC
on the coax switches one Beverage from SE to NW. Two Beverages cover 4
directions.
Don't you think
that's simpler? No extra control cable needed. You can use the
coax as a control cable if needed. That's what I do on one Beverage
here to switch directions. Signal and DC on the coax, easily isolated
with a couple of simple RF chokes and capacitors. You can see them in
the photos of my Beverages. (Schematics above).
Originally
Posted by KA0GKT
> A Beverage
works
best over poor ground, so I would think that running a return under the
antenna may reduce the effectiveness of the antenna by at least a
little.
Answer: You bet
it
will. There is a popular book about Beverages that suggests doing that,
but just because something is in a book doesn't mean that it is
technically sound.
From:
Milt, N5IA
<n5ia@zia-connection.com>
Date: Wednesday,
June 23, 2010, 9:59 PM
"In the most
simple explanation of the theory of operation of the
Beverage antenna
you must
understand that the single wire above (or on) the ground is 1/2 of an
unbalanced transmission line. The earth conductivity is the other
"wire" in the
transmission line.
When the earth
1/2 of the "transmission line" becomes very conductive, the whole array
approaches being an actual 2-wire transmission line (perfectly balanced).
When that happens there is near ZERO signal received.
The more
unbalanced the line is, the more signal level is impressed on the
wire which can
be detected by proper impedance matching to a coaxial feedline going
to your receiver. That is why the Beverage works well over
poor earth."
> I recently
built a two-wire switchable-direction Beverage based on the
> description
in ON4UN's Low-Band DXing (4th edition).
>
Currently, I am using two coax runs to the shack
but will eventually use a single coax that is
> switched
between the
low
impedance sides of the two transformers.
>
> I followed
the schematic in ON4UN's book except for two grounds
which I omitted:
>
> 1)
Figure 7-98A on page 7-70 shows two grounds on the far end of the
>
Beverage. One is the ground on winding n2 of the
transformer, which I
> included in
my Beverage. However, the schematic shows a second
ground (to
> the left of
T5n1), which is connected to one of the two beverage
conductors.
> What is the
purpose of this ground?
This is a typo,
and that ground should not be there.
The only ground at the
right (far)
end of the Beverage should be on the primary of the reflection
transformer (T5a, n2).
It appears that
this drawing was originally Fig. 7-23 on p. 7-22 of the 3rd edition of
the same book. When it was modified for the 4th edition, there was a
ground that should have been removed. I'm looking at both drawings, and
it it's easy to see how such a graphics editing error crept into the
new edition.
Nobody's perfect.
> 2)
Figure 7-98A also shows a grounded connection between coax J2 and
coax
> J1.
What is the purpose of this ground? Since I am using separate
windings
> on my
transformer, I don't think it makes sense to connect
these coax
> grounds to
the ground rod for T1n1.
I agree. On my
Beverages, the coax shields are only
grounded at the station end; and
neither do I
connect the shields at the antenna as shown.
The
ground connection shown
connecting the shields of J2 and J1 in Fig. 7-98 — if used at
all—
should NOT be connected to the same ground as the primary of T1n1,
in order to ensure common-mode isolation.
I have found,
like others have, that it is often unnecessary to terminate the unused
cable in the above design. But I do anyway.
Figure 7-98 above is from the CD-ROM
that came with the 4th edition.
Copyright (c) 2004 ARRL
This
is not to imply that ON4UN's book is not worth having. It is! It
contains some GREAT information about Beverage and other receiving
antennas.
Having said that, it should be pointed out that the Beverage
transformer winding instructions using the 73 material binocular core
in the 5th edition appear to be a departure from earlier editions (and
proven designs by many others). Some of us take issue with the need for
so
many more turns of fine PTFE insulated wire for use with Beverage
antennas.
I'm using a
relay at the feed end of the Beverage that selects the transformer
(either T1 or T4) and switches the terminating resistors across the
secondaries of the transformers, rather than the primaries as is
usually done. Don't think it matters.
Who can verify
that used motor oil will keep my Beverage antennas from accumulating
ice? I know I read it somewhere. I was ready to
coat them using a paint roller, but the ice storm never came.
Read this important info about external receiving
antenna overload at http://forums.qrz.com/showthread.php?t=266646&highlight=beverage
If you do a Google search for "beverage
antenna", you will find a lot of information on them. (Some good,
and some not so good.)
I also have an
as-yet unsorted collection of Beverage antenna information at http://www.w0btu.com/files/beverage/
You would
appreciate the 4th and 5th editions (they are both good to own) of Low
Band DXing by ON4UN, John Devoldere, even
if you're not interested in working DX.
This
page was created because there was no single source for all the
information necessary to build a good two-wire bi-directional Beverage
receiving antenna, either in print or on the web.
It was
initially compiled from
different posts I have made on QRZ.com, eHam.net, the Topband mailing
list, and direct email. We have since added much more; and we are still
adding information, photos, and detailed schematics,
with the goal of enhancing this practical, comprehensive how-to web
page
about Beverage receiving antennas. Thanks for visiting.
Comments, questions, and
suggestions
are always welcome. Contact
us
LINKING:
You are welcome (and encouraged) to add a link to this page from your
site. However, kindly link to
http://www.w0btu.com/Beverage_antennas.html,
and not to the individual files referenced here. Thank you.
A
special thanks to George D. Brown, W8YET (SK) and Tom Rauch, W8JI for
instilling in me the enthusiasm for the Beverage antenna. Many years
ago, Tom kindly explained to me what I needed to build my first
Beverage. And I believe that using 73 material as well as the binocular
core for Beverage antenna transformers was Tom's invention (among other
things).