QRP Contesting in the Wilderness

Inspiration

My story starts six years ago. I had just received a copy of Les Moxon’s book, HF Antennas for All Locations.¹ What a rewarding reading experience—page after page of fresh ideas, all suffused with a zany sense of humor. Then I read the turning point words: “The exploitation of sloping ground…for DX contacts using very low power and simple antennas such as the inverted-V dipole is a fascinating hobby in itself.” ²

Of course! Moxon had just resolved the issue that had been troubling me. Ham radio could be converted from a sedentary, indoor activity into an exploration with three stimulating dimensions: enjoying the outdoor world, developing lightweight radios, and using terrain to significantly improve the performance of antennas.

Since that time, this new passion has kept me busy. I founded an Internet organization, called The Adventure Radio Society, whose mission is to help others combine amateur radio with their love of the outdoors. I’ve learned to use software that helps us assess terrain and to remarkably alter the radiation patterns of simple antennas. And best of all, I’ve had an excuse to explore ridges and peaks in some of the most beautiful country in the world.

The Assault on Carpenter Mountain

This new hobby got off to an interesting start. Moxon’s inspiration struck me just before a QRP contest in the spring. In this part of the world, there is a mountain (Carpenter Mountain—no relationship) whose south slope can be climbed even while snow and ice are blocking the rest of the high country. So I threw everything but the kitchen sink into the largest backpack I own and headed for Carpenter Mountain. The gear included, but was not limited to: Argo II, 7 AH gel cell, Bencher paddle and keyer, MFJ Loop and control box, 10 feet of steel mast, food and water.

At the trailhead I hoisted the pack and got started. After five or six steps I heard an eerie screech, as if a mouse were being goosed. Puzzled, I pushed on. A few more steps and it struck me. That pitiful sound had come from the hiker himself. Later, after I got home, I weighed that pack—78 pounds.

Carpenter Mountain has an abandoned lookout, which seemed just the right place for a QRP contest (Figure 1). I lashed the mast to the railing of the lookout and mounted the loop. What a view! What an amazing place for a radio operation! Five hours later I had learned some lessons in humility. Average signal report: somewhere between 339 and 449. Total number of Qs: 19. Overall results: aesthetics—excellent; radio—miserable.

Regrouping

Carpenter Mountain brought three issues to light:

78 pounds is too much,

Cliffs facing to the south and north are not useful when you live on the West Coast, and

Vertical antennas are a bad choice for HF mountaintopping.

Clearly, I needed to launch this passion again, in a more deliberate manner. Fortunately, just about this time some software tools emerged that made the job easier.

AO³, by Brian Beezley, K6STI, which analyzes antennas and saves the data in Open PF format.⁴ (It is now possible to do the same thing with EZNEC.)⁵

TA, also by Brian Beezley, which converts the Open PF data into radiation patterns based on the refraction and diffraction influences of actual terrain.⁶

VOA-AREA, which plots the signal coverage of data ported from TA.⁷

PropLab Pro which graphs signal coverage in remarkable detail, using ray tracing.⁸

SNApmax, by Crawford MacKeand, WA3ZKZ, which includes an excellent analysis of the all-important question of path losses.⁹

I spent hours with this software, learning what works and what doesn’t. More hours were spent painstakingly creating data pairs from topographic maps. I hiked to the top of ridges and peaks throughout the central Oregon Cascades, looking for the perfect slope. I entered a series of contests from these sites, whether the contests contemplated outdoor operation or not.

Twice, I’ve enjoyed the company of other ham radio operators during my adventuring. In general, however, I’ve been wandering around the mountains by myself. I’ve come to enjoy the solitude of these experiences. Figure 2 shows typical conditions “bushwacking” to the top of a mountain. Figure 3 shows what it’s like on top, and Figure 4 illustrates what the neighborhood looks like.

The aesthetic results of my project have been a complete success. But with respect to the more technical aspects of my investigations, some caveats must be stated now.

The radiation patterns produced by AO and EZNEC for my inverted V are probably accurate, but the patterns predicted by TA are a different kettle of fish. TA only assesses the impact of terrain in a single slice of azimuth. Thus, it is unable to deal with all kinds of “3D” radiation and diffraction that occurs in the real world.

Furthermore, the data pairs derived from topo maps are a rough approximation of actual terrain. There are undoubtedly countless variations that alter the refractions and diffractions and “fill in” the peaks and lobes predicted by TA.

VOA-AREA and PropLab use different algorithms and never entirely agree in their predictions.

I suspect that neither VOA-AREA nor PropLab deals perfectly with the weak signals that are the bread and butter of QRP operation. A good QRP operator can copy a signal that is nothing more than a faint perturbation of the noise. Maybe this is just my personal experience, but I find that I “beat” VOA-AREA and PropLab on a regular basis.

Flat Land Fundamentals

This paper will deal with just one antenna—the good old inverted V. In most cases, it will be an inverted V on a 27 foot mast, since that is the best, all purpose antenna I’ve ever found for back country operation. (See Figure 5.) In all cases, the antenna will be operating at 14 MHz. For my kind of outdoor contesting, 20 meters is the work horse. All of the radiation patterns will be broadside.

On flat ground, the elevation pattern from my inverted V looks like Figure 6-A. Nothing to brag about, but, at face value, most people would say that this is a useful pattern. If we raise the apex to 70 feet, the radiation looks like Figure 6-B. We’re all familiar with the good news/bad news aspects of this pattern. On the one hand, its low angle radiation is greatly improved. On the other, there is a pronounced valley centered at 30 degrees, and our intuition would tell us that the radiation in the high angle lobe is probably wasted.

Getting this little antenna on a slope results in four wonderful outcomes:

The high angle lobe disappears,

The antenna radiates at lower angles,

At certain low angles, there is a startling amount of gain,

We had the fun of climbing to the top of a beautiful place.

But this is the point at which I sometimes lose my listeners. Look, they say. Low angle radiation is fine for the Big Guns, but I just do QRP contests in the United States. Your inverted V with a 27 foot apex on flat ground may not make it to Sri Lanka, but they’ll hear you in Iowa just fine.

How Low is Low Enough?

Actually, if we all lived in Colorado, or thereabouts, a minimal antenna on flat ground might, in fact, be acceptable. But I live on the West Coast. All of us Left Side or Right Side operators face the same problem. Getting to population centers on the other side of the country isn’t so easy. It takes long single hops and, in some cases, it’s a two hop proposition.

Here is an interesting exercise that shows how low angles can be the key to life, and that will also be a warm up for our use of VOA-AREA later in this paper. I created some antenna files for VOA-AREA that are pretty strange. They are isotropic antennas, so they radiate equally in 360 degrees of azimuth. But they only radiate in 10 degree bands of elevation. So they give us an opportunity to test the propagation of radio waves for each 10 degree band of launch angles.

Antenna 1 radiates only from 0 to 10 degrees. Antenna 2 radiates from 11 to 20 degrees, and Antenna 3 radiates from 21 to 30 degrees. By way of example, Figure 7 shows the elevation pattern of Antenna 2. The antenna is launching a continuous band of rays from 11 to 20 degrees, all of which are of equal strength.

Now let’s take a look at a series of VOA-AREA plots, using the three antenna files I’ve described. Each VOA-AREA plot assumes that the time is 0300 UTC, and that the date is Field Day, 1999. The operating frequency is 20 meters, the power is 5 watts, and the transmitter is in Eugene, Oregon. (Collectively, these are referred to as the “standard conditions” later in this paper.)

Antenna 1 generates a great VOA pattern (Figure 8). All by itself, Antenna 1 is covering much of Mid-America. Antenna 2 (Figure 9) is pathetic and Antenna 3 (Figure 10) is DOA.

The foregoing illustration suffers, of course, from an extremely limited scope. It deals with a single time, date, frequency, location and ionospheric setting. The results will be different when any of the foregoing variables is changed. Nevertheless, I have run similar analyses many times for the kind of operating I do (which tends to emphasize daytime operations on 20 and 15 meters). It is amazing how frequently those analyses suggest that low launch angles are fundamentally important, even for contacts within the United States. In fact, most of the time, radiation above 25 degrees is simply wasted.

The standard way to generate 14 MHz rays at 10 degrees or less is to buy a 90 foot tower (and rotator, cable, coax, guys, anchors, fancy antenna, and so on). As I’m sure you’ve sensed from the tone of this article, there is a better way. It requires legs and imagination, but practically no money. Get yourself on sloping terrain, and you’re likely to enjoy antenna conditions that you’ve only dreamed of.

Why a $1.00 Pair of Legs is Better Than a $10,000 Antenna Farm

In the six-year span of my new hobby, I’ve modeled and scouted an embarrassing number of mountaintops. But one doesn’t need to be so compulsive. Pretty soon, you realize that mountains and ridges with certain shapes tend to influence radiation in predictable ways. The only reason I’ve been to the top of so many of them is that wandering around in the woods is my idea of a good time.

Let’s now take a look at four actual mountain sites, accompanied by their TA plots. They are all located in Oregon, but their equivalents could be found many places (although, I admit, certain parts of the Midwest could present difficulties). In all the examples, I assumed that we’re using an inverted V antenna with a 27 foot apex, at the top of steep terrain,, operating at 14 MHz. Each of the TA plots superimposes the plot for flat land over the plot for the sample site.

Breathtaking Cliff

This site (Figure 11) is at the edge of an east-facing cliff that drops 2,700 feet to a large, shallow lake. The terrain is then virtually flat for 20 miles, and finally breaks into rolling hills. It is one of my favorites, even though it’s a long drive. This mountain is one of the largest uplifted faults in the United States, yet most people in Oregon don’t even know it exists. I wouldn’t either, if I hadn’t been looking for the perfect slope.

Big cliffs like this one always produce relatively smooth contours in the elevation plot. Perhaps that’s because there is so much surface area in the cliff that lobes are filled in by a multiplicity of refractions and diffractions. In any event, you will immediately see the dramatic difference between this site and flat ground, particularly in the range of 1 to 15 degrees.

Wimpy Cliff

This site lies at the edge of an east-facing cliff that’s 800 feet high (Figure 12). The terrain in front is relatively flat for about 10 miles, and then rises quickly. The site is close to home, and I’ve operated here many times. I’ve encountered another person on this little mountain only once. Otherwise, the solitude has been perfect. No one else seems to be interested in activating the legs.

Notice the prominent lobes in the elevation pattern. Those lobes are always present with small cliffs. It’s hard to know whether they exist in reality, since the irregularity of the terrain probably tends to fill them in.

Gentle Slope

This mountain has an asymmetrical shape (Figure 13). Although the west face is steep, the east side slopes gently, ultimately dropping about 1,500 feet. I’ve scouted this location, but the gentle east slope has always discouraged me from operating here. The view from up here is outstanding—some people think it’s the best view in the Oregon Cascades. So, one of these days....

Gentle slopes usually have a “spike” of radiation in the lowest angles. Above 10 degrees, the gain drops quickly.

Nasty Mountain Terrain

This site (Figure 14) is about 5 miles from my home. It is typical of many locations in the mountains. There is a modest east-facing cliff, dropping about 600 feet. The terrain in front of the cliff is extremely rugged. This complex terrain produces a messy, somewhat discouraging plot in TA. But you’ll soon see that the plots from VOA-AREA look pretty good.
Using VOA-AREA and ProbLab Pro

The foregoing elevation patterns are stimulating, but, by themselves, they tell us little about how are signals will fare in the real world. For help in that realm, we turn to an entirely different class of software, known generically as “propagation” software.

I have experimented with quite a few propagation packages, including HFx, Wizard, PropMan, Capman, VOA-AREA, ProbLab, and SNApmax. The last three products have been the most useful for me.

However, my favorite programs have flaws. Here are some of them (in no order of priority):

I have found that plotting propagation across a geographical area (which I’ll call “mapping”) is generally a lot more useful than point to point prediction. However, most of these programs lack mapping altogether, or have mapping features that are either poorly designed or inappropriate for ham radio operators. VOA-AREA is the only software that maps in a useful way.

None of these programs make any attempt to link to antenna or terrain analysis software. Furthermore, the internal methods for dealing with antennas are either primitive, or designed for commercial broadcasters, or both. I am lucky to own a little utility written by Brian Beezley that ports antenna data from TA to VOA-AREA, but otherwise I’ve been forced to use very tedious and unsatisfactory methods to generate data for antennas.
As mentioned above, I’m not sure that these programs deal well with weak signals. SNApmax has been useful here, because of its emphasis on path losses. Otherwise, my impression is that the authors were not interested in weak signals.

In general, these programs make no effort to help the user understand propagation. PropLab is the exception here. Its ray tracing and graphing capabilities are impressive educational tools.

There are serious questions about support of these programs in the future. Neither VOA-AREA nor PropLab Pro has had any development for several years. (And I was shocked to learn recently that TA probably has been abandoned.)

In spite of the foregoing grumbles, we can still learn a lot by moving data from TA to propagation software. For a series of examples, let’s take a look at VOA-AREA. In all of these examples, remember that VOA-AREA is assuming that the elevation patterns applies equally to all 360 degrees as azimuth. We know that is not true—the patterns are valid only in an easterly direction. In all other directions, the patterns will be different, because the terrain is different in those directions, and because the antenna’s own horizontal radiation patterns are sometimes different. In short, the maps in this application of VOA-AREA are valid to the east, but not valid in any other direction.

The contours in the plots are expressed in terms of signal to noise ratio. The following table seems to be commonly used for software based on Ioncap (like VOA-AREA).¹⁰ For CW signals, the signal in a bandwidth of 250 Hz is referenced to noise in a 1 Hz bandwidth. For SSB signals, the signal in a bandwidth of 2.5 kHz is referenced to noise in a 1 Hz bandwidth. I’m not sure how relevant the table is for weak signal work, but at least it’s a starting point.

CW Good—44 Fair—34 Poor—24

SSB Good—67 Fair—55 Poor—43

Figure 15 is a “baseline” case, showing how a 5 watt station located on flat ground would cover the United States. We’re back to our standard assumption of 0300 UTC on Field Day, 1999, operating on 20 meters. The antenna is our standard inverted V with a 27 foot apex. The transmitter is in Eugene, Oregon.

To sum it up, the antenna is doing a good job in between 100 and 110 degrees of longitude, and a bad job elsewhere. This would be a disappointing experience in a contest, because most of the living creatures in this part of the country are coyotes.

Now, in quick succession, let’s look at how Breathtaking Cliff, Wimpy Cliff, Gentle Slope, and Nasty Mountain Terrain stack up under identical conditions.

The Breathtaking Cliff (Figure 16) produces breathtaking improvements in coverage. Now, our 5 watts are covering the entire country, beginning at about 110 degrees of longitude and extending to the east well beyond 60 degrees. You could say that our signal would be strong (by QRP standards) in every region of the country east of 110 degrees, except the Northeast, where it would still be readable.

My down-to-earth experience has confirmed VOA’s prediction time after time. When a frequency is getting reasonably close to the MUF and the path losses are down to low levels, it is amazing what a steep cliff will do. I have had experiences in QRP contests where terrain like this produced pile ups that almost scared me. In the search and pounce mode (for example, Field Day), a steep cliff at the right time of the day will produce a remarkable string of one-call pounces.

The Wimpy Cliff (Figure 17) generates a complicated coverage plot. You can see “pulses” of strong signals spreading across the country, separated by zones of weak signals. This, of course, can be predicted by looking at the strongly lobed elevation pattern in Figure 12.

Whether the pulsed pattern is really so well defined is hard to know. As I mentioned before, it is likely the irregularity of real terrain will partially fill in the lobes in the elevation pattern, and thus at least moderate the signal pulses across the country. To the extent that the pulses exist, they might “average out” in a contest situation. That is, the peak of a lobe might produce an excellent signal in one part of the country, offsetting the weak signal that the valley of the lobe would produce in another part.

I’ve had outstanding results from this site. However, if my life depended on it, I think I would select the Breathtaking Cliff. My intuition is that you are better off reaching the entire country with as uniform a signal coverage as propagation conditions will permit.

The Gentle Slope (Figure 18) appears to be a little disappointing. It’s much better than flat terrain, but its signal strength and signal coverage are both inferior to the two cliffs. I’m curious, however, whether the Gentle Slope is producing some pretty good signals in the Atlantic, off the east edge of the chart. In general, gentle slopes seem to produce good radiation at very low angles, particularly if the terrain in front of the slope is flat.

During the last five years, my explorations have concetrated on truly steep terrain, which is abundant in Oregon. But see the discussion of chordal-hop propagation on page 8 of this article. Gentle slopes might be well suited for this intruiging aspect of the hobby.

VOA’s plot for Nasty Mountain Terrain (“NMT”) is actually quite intriguing (Figure 19). At first glance, this site seems inferior. Your intuition would tell you that the jumbled terrain in front of the cliff would create a crazy quilt of refraction and diffraction. But the TA plot of the elevation pattern in Figure 14 looks interesting (albeit messy). And the VOA plot looks downright impressive.

I don’t know if TA’s “2D” way of looking at terrain is appropriate in a very complex mountain setting. But if TA is even close, then NMT is, in reality, an interesting place to operate
The best part about NMT is that it’s easy to find. Ramble around on any mountain, and you find steep slopes with jumbled terrain in front. This particular NMT is exactly 15 minutes from my house. I generally go up there for Norcal’s QRP to the Field in April, because the high country is still covered with ice and snow. Even though the setup I use in that contest is very simple, it always seem to be one of the top performing stations (measured in number of Qs).

We’ll wrap up this look at propagation from mountain tops with a little reality checking. This is where PropLab Pro shines. It is powered by different algorithms than VOA-AREA, and its graphical presentations are unique. I’ve always found it easier to believe VOA-AREA if PropLab Pro comes up with similar predictions. As a side benefit, PropLab is the best educational tool I’ve ever found among the propagation programs.

For starters, lets see what PropLab Pro predicts for flat terrain, using our standard assumptions (Figure 20). The “X” marks the point at which PropLab thinks that the signal merges into the noise. PropLab documentation admits that it’s not a precise calculation, but I’ve found it useful. Figure 20 traces rays every two degrees, starting at 1 degree and ending at 30 degrees. The rays are traced in a single slice of azimuth, starting at Eugene, Oregon and passing through the center of the East Coast.

Figure 20 appears to agree reasonably well with the VOA-AREA predictions. It tells us to expect fairly weak signals in a single skip zone, extending from about 1,500 to 2,000 kilometers.

Here is another reality check. We’ll use PropLab Pro to assess propagation from the Breathtaking Cliff, otherwise using the standard assumptions (Figure 21). Once again, PropLab Pro and VOA-AREA appear to be in agreement. Both Figure 16 and 21 anticipate signals across the United States, starting at about 1,500 kilometers. If we wanted to examine the zone between 3,000 and 5,000 in more detail, we could increase the “resolution” of PropLab Pro by tracing rays at closer intervals than 2 degrees.

The Arsenic Hours

Imagine that you are the 20 meter operator for a Field Day team. Your job is to operate 20 meters all day (and all night) long, through thick and thin. As you well know, there will be times when 20 meters will go to the dogs. We’ll call those slots the Arsenic Hours.
During the Arsenic Hours, does it do any good to be on the top of a steep slope? The answer is a little, but not much.

In my part of the world, during Field Day the Arsenic Hours for 20 meters occur in the middle of day. Let’s take a look at what both the flatlander and the mountain top operator can expect at 1900 UTC. Figure 22 shows the humble results you can expect from the baseline case—the inverted V on flat ground. We’re covering a narrow band around 1,700 kilometers from the transmitter, plus some dubious short skip, all with weak signals.

Now let’s switch to the Breathtaking Cliff (Figure 23). Once again, we’re using the inverted V at 1900 UTC. This pattern is better than flat ground, but it’s not great. Compare it to Figure 21, where the low radiation angles are producing outstanding coverage.

We’ll close this section of the paper with a glimpse at path losses—a fascinating and critical question for those of us who think that six watts is too much. SNAPmax is especially illuminating here, by including a comprehensive analysis of what eats our signals.

I’ve included two graphics from SNAPmax. Both graphics give us an idea of the relationship and composition of signal, noise and losses on a path between Oregon and Delaware. I haven’t yet learned how to custom design antenna files for SNAPmax, so the graphics simply assume a 14 MHz dipole at 75 feet over flat land. Figure 24 assesses signals, noise and losses at 0300 UTC, while Figure 25 assumes that it’s 1900 UTC. In Figure 25, noise is in excess of the signal, and the villain, as you might expect, is middle-of-the-day absorption.

What’s Ahead

In the perfect world, someone would get interested in writing software that is truly systemic. Right now, antenna analysis and propagation prediction are treated as if they were separate issues. But, in reality, neither realm makes much sense without input from the other. Antenna radiation patterns are pretty useless if they don’t take into account the complex terrain in which antennas actually operate. Propagation predictions are highly misleading if they don’t include antenna data that is far more sophisticated, or relevant, than the antenna data currently used by the propagation programs.

As things currently stand, porting data from antenna software to propagation software is tedious and complicated. I’ve done a certain amount of it, to satisfy my own curiosity and to write pieces like this one. But this hobby would be more rewarding if the computer professionals wrote systemic software, or, at the least, easy-to-use porting utilities.
But I don’t mean to whine. Once you’ve caught on to the effect of steep terrain, you don’t really need software. You’ll know a sweet looking cliff when you see it.

And I suspect that the best part of this hobby lies ahead. The very low angles of radiation produced by steep cliffs with flat terrain in front are perfect for propagation known as “chordal-hop” or “tilt mode.”¹¹ It should be possible to work very long distances with low power and a minimal antenna. For example, Moxon’s book tells of working Australia from England, running 1 watt SSB to a portable inverted V.

I’m anxious to give chordal-hop propagation a try. Recently, I’ve been pouring over maps of the Oregon coast, looking for promising cliffs. I imagine that there are many potential sites for chordal propagation throughout the United States. It would be especially rewarding if a group of us could get interested in chordal propagation, so we could share our experiences. In the best of all worlds, we’d get operators on all of the continents interested in the same thing. To my mind, the ultimate low power thrill would be two-way QRP contacts with operators across the globe, using simple, portable antennas and equipment.

Another fascinating possibility is some “A/B” testing. For example, the top of the Breathtaking Cliff is a sizeable, virtually flat area, in the nature of a mesa. It would be easy to set up two identical stations, one at the edge of the cliff, and one on the mesa, a quarter of a mile from the edge. With the cooperation of amateur radio operators across the country, we might be able to develop useful data. Ideally, we’d test from 10 meters to 80 meters, during appropriate times of the day and night. Short of renting a helicopter, this may be the only reality-based way to test the performance of steep terrain.

Yet another project for the future is experimenting with sites that are on the sides of cliffs, rather than the tops of cliffs. Moxon believes that the sides of cliffs are superior.¹² I’ve had a hard time testing his point of view, because most cliffs in the Cascades are seriously steep. Up to this point, I haven’t able to find a ledge that could contain both an antenna and me. But sooner or later, the perfect ledge will make itself known.

This summer, try this. Put some radio gear in a day pack and take a pleasant walk to the top of a slope. Put up a simple antenna. Enjoy the view. Work a few stations. Heaven!

******

The author thanks Wes Hayward, W7ZOI, for reviewing this paper and countless other gracious offers of assistance. Any mistakes, however, belong to the author alone.

Notes

¹Les Moxon, G6XN, HF Antennas for All Locations, 2nd ed. (Herts, England: Radio Society of Great Britain, 1993)

²Ibid. p. 171

³TA and AO are antenna software programs formerly developed and marketed by Brian Beezley, K6STI. The author understands that Beezley has declared his intention to cease developing, marketing and supporting all of his amateur radio software products, including TA and AO.

⁴OpenPF is a data standard for antenna plot files developed by Beezley. It was not marketed separately, but was incorporated in TA and other antenna software products. See The ARRL Antenna Compendium, vol. 5 (Newington, CT: The American Radio Relay League, 1996) p. 77.

⁵EZNEC is antenna software developed and marketed by Roy Lewallen, W7EL, POB 6658. Beaverton, OR 97007. Email: w7el@teleport.com. Phone: (503) 646-2885.

⁶The 19th edition of The ARRL Antenna Book (Newington, CT: The American Radio Relay League, 1997) includes a program called YT, which apparently is similar to TA. The author has not used this program, because it appears to be useful only for yagis with two or more elements. However, with Brian Beezley’s apparent exit from the amateur radio market, TA may, as a practical matter, disappear. In that event, YT may be the only remaining antenna program whose purpose is to evaluate the effect of terrain on elevation patterns of antennas.

⁷VOA-AREA is propagation software developed by the Voice of America. It can be downloaded, without charge, from: ftp://ftp.voa.gov/pub/software/voacap/.

⁸PropLab is propagation software marketed by the Solar Terrestrial Dispatch. Email: Oler@Solar.Uleth.Ca. Web site:http://solar.uleth.ca/solar.

⁹SNApmax is propagation software developed and marketed by Crawford MacKeand, WA3AKZ/VP8CMY, 115 South Spring Valley Road, Greenville, DE 19807. Email:jcbmck@edel.edu.

¹⁰ VOA-AREA defines signal to noise ratio as “the hourly median signal power in the occupied bandwidth relative to the hourly median noise in a 1 Hertz bandwidth.”

¹¹Chordal-hop propagation was discovered by H J Albrecht in 1953. His work confirmed the experience of amateur radio operators over a period of more than 50 years, who had received consistent S9+ signal report over a distances of more than 12,000 miles. Under certain conditions, radio waves experience multiple reflections within the ionosphere itself, benefiting from a “focussing gain” and avoiding the losses of ground reflections. See the fascinating discussion in Moxon, op. cit. pp 5, 15-16.

¹²Moxon, op. cit. pp 165-167

*******

Russ Carpenter, AA7QU, is co-founder of The Adventure Radio Society. He lives in a log house on the McKenzie River, near Eugene, Oregon.

russ@natworld.com