The Art of Launching Rays--The Joy of Middleness
By Russ Carpenter, AA7QU
The Sojourner
In the May Installment of "The Art of Lauching Rays," we looked at the impact of antenna height on the propagation of 20 meter signals from the West Coast across the country. In this installment of "The Art of Launching Rays," we'll examine a different question. How much does your location within the country affect your success in a QRP contest? We'll use the same format as the May issue, looking at 20 meter propagation patterns every two hours.

I chose the subject on the basis of personal experience. In just about every daytime 20 meter contest I've entered, the stations in the Mountain states have cleaned up. I've ended up with a case of Colorado envy. Is the Middle a great place to be, or is it just my imagination?

The following linked graphics are pretty big--8.5 inches wide and 17.5 inches tall, meaning that you'll need to scroll through them vertically. But the files are highly compressed and won't take long to download. The story they tell is fascinating, so don't skip them.

Three colors are used to indicate signal levels (expressed as signal to noise ratios). Blue means 26 to 30 dB (marginal), green means 31 to 35 dB (good), and yellow means more than 35 dB (very good ). These are not the same anecdotal quality ratings used in the literature, but I've found that they fit QRP operating conditions pretty well.

Each graphic has three charts, centered on San Francisco, Denver and Philadelphia. We'll refer to those regions as the "West Coast, Middle, and East Coast" respectively.

One last technical matter. This discussion uses the term "Coyote Factor." It means that certain areas of the country are sparsely populated by humans, but intensely populated by coyotes.

1400Z is a toss up. The West Coast has a slight advantage, but it's nothing to brag about. None of the regions is suffering from the Coyote Factor.

1600Z goes to the Middle. The West Coast is covering about half as much of the country as the Middle, and is also hurt by the Coyote Factor. The East Coast is a miserable place to be.

1800Z also goes to the Middle, for essentially the same reasons as 1600Z.

2000Z starts to get interesting for the East Coast, but it still comes in second to the Middle. The West Coast is plagued by short skip distances, landing squarely on the heads of coyotes.

2200Z is a sweet time for the Middle. In second place is the East Coast, but it's only covering about half the area as the Middle. The West Coast is getting better, but far too many of those rays are warming the fur of certain four legged animals.

2400Z is simply stunning for the Middle. Both the East Coast (in second place) and the West Coast (in third place) have improved, but they can't approach the Middle.

0200Z is, once again, the time to be in the Middle. The West Coast has now moved up to second place with good area coverage, much of which is damaged by the Coyote Factor. Conditions on the East Coast are decent, but third place,

0400Z finally gives a little glory to the West Coast. The East Coast is in a weak second place. In the Middle, the skip is so long that most of the rays are landing in the Atlantic and Pacific Oceans.

A few concluding observations:

1. It's not quantified on these charts, but the Coyote Factor is serious business.

2. On 20 meters, the way to avoid the Coyote Factor is to get thyself into the middle of coyote country, which happens to be the Middle.

3. These charts show single hop propagration (They're capable of showing double hop, but Ioncap didn't think that five watts into a simple antenna could make two hops.) The only way to thrive in a single hop environment is to get in the Middle.

4. If you're a left or right coaster, and can manage to launch two hop QRP rays, the whole game changes. It's still tough to win, but you can give the Middle a run for its money.

5. There are four ways to launch double hop QRP rays from the Coasts:

(a) Get lucky with superb propagation;

(b) Enter a contest that has just a few hours of duration, all of which favor double hops from your location;

(c) Reduce your launch angles with a high antenna, or steep terrain facing the right direction;

(d) Increase your radiated power with a gain antenna.

Tech Notes

1. The charts were prepared with VOA-Area. The date was September, 1998 and the SSN was 90.

2. Isotropic antennas were assumed at both the receiver and transmitter ends. Isotropic antennas tend to underestimate performance at moderate to high radiation angles, but overestimate performance at low angles

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Russ Carpenter, AA7QU, is a contributing editor to The ARS Sojourner and lives on the McKenzie River, Oregon.