From Brushbeater: Beverages for Listening

[Lawless]

https://brushbeater.wordpress.com/

This is a re-print of Keypounder’s article on Beverage Antennas that originally appeared in Sparks31’s Signal-3 in the same issue my article on Afghanistan was published. In my assessment, its a very well written introduction to not just what Beverages do and why they are important, but how to build them. He very generously allowed it to be re-posted here. Use it!

My Sunday School teacher always taught us that it was better to give than to receive, but when I got into amateur radio as a teenager, I quickly learned that receiving and listening are much more important than transmitting. If you can’t hear them, you can’t work ‘em! I was also taught that the key to successful listening was having good antennas; good receivers were important, but good antennas were essential. On the upper HF bands, say 20 meters (14 mHz) and up, this is relatively easy; get a good dipole or longwire 35 or 40 feet up and you’re set.

But the lower HF bands are different, because of the size of the antennas required, the low effective height of the antennas, and the physics involved in propagation on the lower HF (40 and 80 meters); the Medium Frequency bands, (160 and the AM broadcast bands) much more so. One consequence of these factors is that most low-band transmitting antennas emit primarily high-angle RF. This in turn means the following:

• low-band transmitting antennas disproportionately pick up high angle atmospheric noise;
• Low-band transmitting antennas put most of their RF into higher angle paths, with a much smaller proportion of the transmitted energy going into the low angle RF needed for long haul communication.
• Low band signals do not usually propagate as well as upper HF does when the upper HF bands are open. 160, in particular, is noted for odd ducting propagation modes, but in general the greater signal attenuation and greater difficulty in propagation on the low bands make low band operation more difficult. Long-haul signals received on transmit antennas challenge the limits of modern receiver technology.

“Well,” I can imagine some readers saying, “Why operate on the low bands, especially in the summer, anyway? They’re fine for NVIS, but if I want to talk to the opposite coast or overseas, I’ll get on (upper HF band of choice) and work them with no trouble!”​

 

[Lawless]

It is true that when the upper bands are open, you can work the world on a few watts. Some time back, I made a transcontinental contact using a wire beam antenna hung from two trees on 10 meters, using SSB and 8 watts. My signal report was 10 db over S9; the operator on the other end was surprised when he was told what sort of setup I was using. When the propagation is good, and the bands are open, upper HF is very efficient. In the context of a hobby, waiting for good conditions is fine. But when your safety and well-being, or that of your family and friends, requires being able to provide communications at need, you may not be able to wait, and this is where operating on the low bands becomes important.

We’ve passed the peak of Solar Cycle 24, and we are headed back down to the bottom of the sunspot cycle; mediocre as the peak of SC24 was, in just a few years even 20 meters is likely to be dead except during broad daylight, and possibly dead even then. Cycle 24 is now confirmed as one of the lowest in over a hundred years, and 25 may be lower still. During the bottom of Cycle 24 and the buildup to the peak of Cycle 25, the low bands will be the backbone for night-time reliable long haul communication, 40 and 80 meters especially.

If you are serious about being able to communicate effectively locally, regionally and internationally under all conditions, then the low bands have much to offer, if you have the knowledge and skill to use them. So, what factors contribute to successful low band operation?

Even though my first operating experience was on 80 and 40 meters, it took me a while to notice that all the really successful operators on the lower HF bands (160, 80 and 40 meters, or 1.8, 3.5 and 7 mHz) all had one thing in common; they all had listening antennas. We’ve discussed the issues with using transmitting antennas for reception on the low bands; why are listening antennas so important? Why spend the time and go to the bother of putting up a listening antenna when you already have an antenna?

Because, especially on the lower HF bands, the requirements for hearing a signal, for receiving, are different from the capabilities of most common transmitting antennas. As mentioned above, the lower bands are noisier, both from atmospherics and man-made noise, and what makes the difference when listening is the ability to improve the signal to noise (S/N) ratio. Most modern receivers have plenty of gain, so signal strength is not as big an issue.

S/N defines how well you can pick out the signal that you want to hear. Whether the received signal is weak or very loud, whatreally matters is how much louder it is than the noise. It is not at all unusual for the base noise level on a nice summer evening on my elevated 80 meter dipole to be a steady S9 or even 10 db over that, with static crashes peaking at 20 to 40 db over S9. In order to be readable, the signal, even a CW signal, has to be louder than that. This is where the listening antenna comes in.

In many ways, listening antenna requirements are the opposite of everything one wants in a good transmit antenna. Good listening antennas are low to the ground, to minimize noise pickup, and they are directional, to reduce both noise and unwanted signal levels. If you can reduce the noise your receiver hears by 40 or 50 db, even if the signal you want is reduced by 20 db, the net gain in S/N is 30 db, which makes it easy copy. That is why the good operators spend days and weeks setting up listening antenna arrays; they WORK.

There are all sorts of listening antennas to try, but in the context of grid-down long distance communications, one stands out. I suggest you consider the Beverage, and specifically the Beverage On the Ground, or BOG antenna. No, I am not talking about spilled beer, but about a long wire antenna, lying on or just above the ground, named after its inventor, Harold Beverage. I’ll have some links for those who are interested in doing more research in the bibliography for this article.

If you are like many people, (including many licensed radio operators!) you have to be asking yourself, “Is this guy joking? An antenna ON THE GROUND? Nah!” No joke, it really works, and it is amazingly inexpensive, quick and low profile. All you need is about 100′ or more of almost any kind of insulated wire, a simple transformer, a ground rod and enough coax to connect to your receiver. This simple directional antenna, which can fit virtually unseen onto a modest suburban lot, will allow you to pull in distant low frequency AM broadcast stations, signals from ham operators and shortwave broadcast stations on frequencies up to 10 mHz or so, despite the summer time noise.

Being able to reliably receive news and information from around the world in the aftermath of a grid down event is a huge advantage. The very first Beverage I ever deployed, built for a friend from a book, took about 3 hours from a standing start to complete and on the air, including a trip to Home Depot for materials, and the performance was amazing. My buddy was able to copy stations using the BOG that he could not hear through the noise on his transmit antenna, a ¼ wave vertical.

So, what do I need for a Beverage On the Ground?

A simple Beverage on the ground requires the following-

-100′ to 150‘ of insulated wire (doesn’t need to be all one piece or even all the same size, but joints should be insulated);

-Ground rod(s) or ground radials, or both;

-A simple impendance transformer;

-enough coax or other transmission line to run from the antenna wire to the receiver;

-misc tools and connectors.

(A detailed material and equipment list follows the text of this article.)

 

[Lawless]

Wire-

For my simple BOG antennas, I use 14 gage THHN house wire, which is sturdy and double insulated, and comes in a variety of colors. If you want the antenna to stand out, use bright red or orange; I usually prefer the brown wire which blends in nicely with the ground. If you are piecing wire together, make sure the connections are soldered tight and that they are fully and completely waterproof.

Ground rods-

I take an 5/8 diameter 8‘ ground rod and cut it in half; this gives me two ground rods for about $12. If your soil is not rocky, you can use copper pipe for a ground rod, reinforced with a wooden dowel at the top to reduce mushrooming, and if budget is a particular concern, scrounged 1/2“ galvanized pipe will work too, especially with a couple of bare copper wires looped through the pipe and up the outside. If really stretched, a piece of rebar would probably work, too, although I have not tried it.

Enhancing the conductivity of the ground is a good idea; Epsom salt (magnesium sulfate) solution is the ‘school answer,’ and it works very well although I would not use it with a few feet of any concrete structure, but urine works too, and so does plain water. If you use urine, keep in mind that if you are moving around you’ll be handling the box and the ground rod, so remember the restroom sign- “We aim to please- we hope you aim too, please!”

Impedance transformer-

The impedance of a BOG antenna runs from about 200 to 300 ohms, depending on soil type, height above ground, and other factors; you’ll need to find an approximate match between the antenna impedance and the transmission line you are using. If you are using 75 ohm RG6 television coax, as many do, then an impedance ratio of about 3 or 4 to 1 is about right. This is what one looks like; I use a 73 mix binocular toroid (Fair-Rite p/n 2873000202) with 24 gage teflon and 26 gage enameled wire. You can buy these from Mouser or Allied very inexpensively; I get a couple dozen at a time and they cost 50 cents apiece in bulk. A group buy will save money over one-at-a-time, or you might find them at a hamfest. For less than a dollar you can make a good BOG transformer.


Some folks directly connect the coax to the antenna and ground, but there are a couple of issues with this approach. One is that doing that couples the outside of your coax to the antenna and enables your coax to become part of the receiving array, eliminating the directional ability of the Beverage and increasing reception of unwanted signals and noise. The other is that the significant mismatch in impedance will reduce the already low signal level still further, and may make your beverage a bit ‘deaf’. It can and has been done, but such shortcuts do significantly impair the perrformance of the BOG. Better to make a transformer, even a field expedient out of a nut or a small piece of pipe.

Don’t get too panicked about making a transformer or impedance matching. If you don’t know what impedance coax you have, then do this: put three turns of insulated wire through both holes of the binocular core and leave 4“to 6“ legs. This is the primary, and hooks to the coax, one side to ground and one side to the center conductor or hot lead. Then run 5 turns of wire through both holes of the binocular core and leave 4-6 inch legs. This is the secondary and one leg goes to the Beverage wire terminal and one goes to the ground clamp. If I had to make a BOG from field expedient materials, I’d use a chunk of Cat 5 or Cat 6 cable for wire, and a steel hex nut for a transformer core. As good as my ferrite binocular toroid? No, but it will work.

 

[Lawless]

It is a good idea to weather proof the transformer assembly and the connections to the antenna and the coax; here is how I do it.

I spent about $6 for the box, $2.50 for the SO-239 connector, about $3.50 for the two zinc ground clamps, and about $2 for the brass nuts and bolts from Home Depot. I put the SO-239 on the bottom of the box (3/4“ hole with 9/64” for the brass attachment bolts) , the ground clamps on the back (1/4“ holes) and I pick a side for the Beverage wire terminal (3/16“ hole) Here is another view –

As a field expedient one could do well with a cottage cheese container or any sort of plastic container sealed with tape or silicone sealant.

One needs transmission line to go from the transformer at the end of the BOG to the receiver; typically this is RG58 or RG6 coax, but you can use twisted pair line or even 16 gage insulated landscape wire which has an impedance of around 125 ohms; if you do this, then adjust the transformation ratio accordingly when winding your transformers. I ran across a 500‘ roll of new old stock RG6 for $20 at a ham-fest recently and this cheap coax works just fine for short term use. Longer term, the flooded quad shielded coax sold by DX Engineering and others is a better bet, as mice and other vermin apparently don’t like the taste of the goo that fills the coax.

RG6 is bigger and heavier than RG58, so if weight is an issue, use RG58. If you scrounge around you can often find perfectly good used coax being pulled out of a remodeled home; if you ask the electrician he may simply give it to you. Home Depot sells a 500‘ roll for $50, or 10 cents a foot. If you are on a typical suburban lot, you probably won’t need more than 100‘ of coax; another opportunity for a group buy.

When using coax, I use coax connectors to join things together, as this makes it easy to disassemble and relocate the antenna system; RG59 adapters for solder connected pl-259 (common VHF connectors) work well for RG6, and RG58 adapters are readily available commercially. These are probably cheaper for lower volume operators to do, but you do need to solder the connections, which may take time and if you haven’t done it, you are likely to ruin some cable and connectors learning how. I messed up my share of connectors learning how, but after over 40 years in radio and electronics I can do a good soldered PL-259. (A quick tutorial- the secret is being able to apply LOTS of heat very quickly and precisely to avoid melting the insulation of the cable and the connector. Silver plating helps, and so does Teflon insulation…)

These days, though, I don’t solder most of my connectors. I make a lot of cables and antennas, so I bought the required commercial crimping tools, and I mostly use crimp-on connectors for my cables as they are much quicker to produce, especially with the commercial coax prep tools available for RG-8, RG-6 and the smaller cables. You may have somebody local to you that has these tools and can make your cable up for you, or you can buy commercially made coax assemblies from dealers. Any PL-259/SO-239 connector/connection is NOT waterproof, so I waterproof these connectors and their connections with a combination of liquid electrical tape, Coax seal (moldable rubber tape) and regular hand wound electrical tape.

So, you have your BOG wire, your transformer box, your ground rod, and your coax with appropriate connectors. Drive the ground rod, attach the Beverage box to the rod with the ground clamps, attach the wire to the box and stretch it in the desired direction, and attach the coax and run it to your receiver input. Waterproof your connections if they are going to be there for more than overnight. Don’t get too hung up on maintaining a perfectly straight antenna; minor zigs and zags make no difference, and some up and down in the wire run doesn’t much matter either.

Compare the signal with what you hear on an elevated dipole or vertical transmitting antenna. Be prepared to be amazed at what you hear, and DON’T hear! You will hear broadcast band stations in your chosen direction that you cannot otherwise hear, day or night; you will hear 150, 80 and 40 meter amateur signals that were otherwise unreadable; and you will be able to pick up shortwave news broadcasts that have information you will never hear on the mainstream media. What you won’t hear is about 6-9 S-units of noise, and that is the best part. Comms UP! Enjoy your Beverage!

73, Keypounder.

Material list Cost

100-150 feet of insulated wire $7 to $15

4“ x 4“ x 2“ insulated PVC electrical box $6

1 ea #10-24 2“ brass bolt

3 ea #10-24 brass nuts

4 ea #10 brass washers

( the #10 hardware makes up the Beverage wire attachment point)

2 ea #6-32 3/4“ brass machine screws

3 each #6-32 brass nuts

4 ea #6-32 brass washers $2 or less net in bulk

(the #6 hardware holds the SO-239 socket to the PVC box)

1 SO-239 socket (recommend silver plated with Teflon insulator)

2 each PL-259 VHF plugs with adaptors $6 net

2 zinc ground clamps $4

50-150‘ of RG6 coax cable $5 to $15

Misc electrical tape and liquid tape, allow $5

Ground rod $0-$12

Tools-

Multimeter (check coax and beverage box for connectivity)

Soldering iron (100 watt plus recommended for PL-259 connectors)

60-40 electronic solder (DO NOT use acid core, get rosin core flux solder)

Drill bits- 9/64 for the #6, 3/16“ for the #10, 1/4“ for the ground clamps.

Reloading reamer to widen the hole to 3/4“ for the SO-239 mount.

Screwdrivers and nut drivers for the screws and nuts (Leatherman tool works)

Pocket knife or coax prep tool.

Bibliography-

“Low Band Dxing” 5th Edition by ON4UN, John DeVoldevere.

Chapter 7 is on listening antennas, and section 7.2 is all about Beverage

antennas. The BOG section is 7.2.12, page 7-84.

“The ARRL Antenna Book” 13th Edition. If you are interested in antennas, this is a must-have reference. If you are buying a used copy, make SURE that you get the CD-rom that comes with it; EZNEC and much good added information is on there.

Web links of note-

http://www.antennasbyn6lf.com/2015/04/nec-modeling-of-wire-close-to-andor-buried-in-soil.html (Rudy Severns, N6LF, has done some very good work on antenna research and design; his whole site is of interest to any antenna afficianado)

http://www.qsl.net/wb5ude/bog/

http://www.qsl.net/k1fz/bogantennanotes/

 

[htperry]

Beverage on the grass antenna is also know as a "grasswire antenna". They are quiet. I have thought many times about a grasswire on my IC756 Pro III receive antenna connection. http://f5ad.free.fr/Liens_coupes_ANT...ne%20gazon.htm

Thanks for the post.

Edit: this is also an excellent antenna to use cable TV RG-6 or RG-11 75 ohm coax due to the lower received signal loss than 50 ohm and low cost.

 

[georgel]

Who doesn't like a nice beverage for listening?