Beverages for Listening, I

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!”

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, what really 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.)

2 thoughts on “Beverages for Listening, I

  1. Pingback: Brushbeater: Beverages | Western Rifle Shooters Association

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