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1-9 of 9 messages
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Antenna shootout results
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by KK7HO on September 21, 2009
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Here's a link for those that may not have seen the antenna shootout results. The Scorpion Antenna made a great showing. I've had one in operation for over a year and it hasn't missed a beat.
http://www.scorpionantennas.com/3.905-century-club-shoot-out-results-2009.html
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RE: Antenna shootout results
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by K0BG on September 22, 2009
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You can bet that one six-lander is other than pleased!
Alan, KØBG
www.k0bg.com
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RE: Antenna shootout results
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by K6TFZ on September 22, 2009
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It's expected that the Scorpion did so well because the coil was so high and in the middle of the pickup bed with lots of metal bonded and under it. What I'm interested in is why the Hi-Q did so poorly compared to other antennas which were mounted similarly to the Hi-Q. Geoff, K6TFZ
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RE: Antenna shootout results
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by K0BG on September 22, 2009
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It's simple actually. The cap hat used was mounted too close to the coil. If you want additional information about this, go to my web site and read the Cap Hats article.
There is another reason too, which becomes even more apparent as you increase the frequency of operation. Self-resonance as it were.
The end cap of the HiQ coil is aluminum, although stainless steel is available. When you move the plunger towards the top, both it and the end cap greatly effect the Q of the coil. As a result, it is possible to use a large cap hat, and tune the antenna to resonance on 17 meters, yet use the antenna on 15 through 6 meters with less than a 3:1 SWR. The occurs because the metal within the field of the coil, causes it to look more like a capacitor instead of an inductor. Or, as I said, operate above self resonance.
If the cap hat is large enough, like the reentrant one used, and mounted too close to the coil, the losses in the coil become very large, no matter the static Q.
The bottom line is, you lose more than just a questionable contest.
Alan, KØBG
www.k0bg.com
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RE: Antenna shootout results
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by WX7G on October 27, 2009
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Given the variables of the vehicle, the shootout results are ok for owner bragging rights but are meaningless for comparing antennas.
To fairly compare antennas they each need to be installed on the same platform.
The pickup truck with the bed antenna mounting provides a clean test platform.
Manufacturers should not use data biased in any way for advertising purposes. This particular shootout data is biased by the vehicle installations.
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RE: Antenna shootout results
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by WB5JEO on October 27, 2009
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Well, it's not really an "antenna shootout," is it? It's various antennas mounted in various ways on various vehicles with likely some variations in grounding, feeds, etc. Looking back over all the years' results, it's pretty clear that any number of different antennas can come out on top in any given year, some of them clearly not on account of the virtues of the antenna alone. In other words, a casual bragging rights sort of fun thing.
But I was amused by the lawyer letter on the site. Four out of five dentists agree that's dumb. Follow the practice enforced (deadly serious about it) on their field reps in the 70's by IBM. Never say anything bad about the competition, even when they speak ill of you. And don't make threats, especially silly ones. Quoting Tuco (The Ugly): "When you have to shoot, shoot, don't talk."
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RE: Antenna shootout results
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by KJ4DKT on November 21, 2009
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today i mounted a h/s sidekick on the roof of my truck w/a mag mount (T_-bar). the manual says to not do it this way. i tuned it to 20m and talked to Bahamas, S. Dakota, Michigan, and other states always w/ s9 and better. the magnets are bare and the paint on the roof is bad. this may be the reason. the mags are directly grounding to the sheet metal. i have no grnd straps.. IT WORKS BEAUTIFULLY!!!!! im leaving it alone and continue to talk my head off. your milage may vary. fred kj4dkt it also tuned up to 10m w/no probs..i will try 75m tomorrow.
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RE: Antenna shootout results
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by K5END on November 23, 2009
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One question (among others) I have about the shootouts is the method of measurement.
If I understand correctly, all the remote measurements are taken at ground level "several wavelengths away." If that is correct, then the data isn't worth a lot (which everyone seems to agree upon anyway.)
How about measuring at 10 degrees elevation from 20 or more wavelengths away? It wouldn't be easy to do this, but it could be done.
For 80 meters that would require a tower at slightly more than one mile distance and about 300' high. Surely it's not hard to find flat, unobstructed land within a mile of a 300' tower or hill, right?
Another way is to use a nylon-guyed helium blimp (commonly available) and attach the calibrated antenna to it. That method also offers an easy way to measure signal strength as a function of height, continuously. All you need is a winch or two (but a few wenches will work just as well.) I'm certain that Hams are innovative enough to do this.
Instead of having a circle of guys around the azimuth making measurements around the vehicle, just rotate the vehicle or test platform. It could be done in small increments this way and probably be more consistent.
Above all, a calibrated transmitter and antenna should be used throughout all the measurements during the day to normalize the data against any environmental changes.
If we're going to get po'ed about a shootout, at least let us get scientific about the method so we can know exactly what we are getting po'ed about.
Just by looking at the data from this year's shootout, I'd say the method needs some improvement. There are obviously hidden variables. Some of it makes no sense at all.
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