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In Reply to: so if I'm reading you right posted by bartc on November 27, 2006 at 09:51:25:
I haven't
actually tried one of those expensive whips, but from the descriptions I've
seen about their performance, it is very likely the vertical folded dipole
will perform as well. Their claim of 3dB higher gain than a dipole (horizontal) seems based on the fact that at heights under about 15 ft., vertical mounting of an antenna increases it's gain by as much as 3dB. Of course the vertical dipole isn't a substitute for a roof-mounted
yagi where extreme distance is needed, or significant directionality. It's
just a cheap way to get good reception in suburban areas, certainly better
than a rabbit ear or folded dipole sitting atop the receiver cabinet. For
example, I also use an Antennacraft FM-6 small log-yagi, the old FM band
Radio Shack antenna. It's in the attic on a rotator, and it
doesn't usually produce higher signal readings than the vertical folded
dipole, but the resultant sound is cleaner, much less background hiss and
"sshh", etc. I attribute that to its much better directionality vs the vertical dipole (omnidirectional), which
rejects a lot of same channel and adjacent channel signals at different
azimuths from the desired signal.
Follow Ups:
Remember vertical mounting places the nulls in the vertical axis, so there is no figure 8 side null. This can either hurt or help. What does this mean? a folded dipole accepts signals perpendicular to the length of the antenna, and rejects signals that come parallel to the length.
When horizontal, if it is positioned with the broad side facing N-S, it will reject stations from E-W. If you have multipath problems, in many cases the horizontal antenna can be positioned to reject the multipath bounce. Not true of a vertical dipole. A log periodic (many people incorectly call a YAGI) rejects all but the front, making it excellent for multipath problems when optimized with a rotor.
A directional outside antenna is clearly in my future. I live in a fringe area, and my home is in somewhat of a valley, but I use a dipole right now because I listen to public radio 90% of the time, and there's an excellent station nearby. I attribute the improvement in sound to a reduction in multipath, but I also have to note that there's been a distinct increase in signal strength. The bottom line is that it works better - much better - and that's with the antenna in a second floor listening room mounted vertically along the edge of a window casing. A good mast, rotor, and antenna setup will cost several hundred dollars (a good deal of that for the mast), but will also give me much better directional selectivity. That's something I definitely need in my location. It will happen eventually, but for now I'm content.Regardless of where the tip came from originally, I'm grateful for having gotten the benefit of the knowledge.
Believe me, you don't need to spend hundreds!On reading his site I took the chance on a Radio Shack with his easy mods. Works beautifully, even on the ground!
You might indeed need a rotator - I didn't. But you can get a RS model for $24 (returnable), their better balun for $6, use PVC pipe for under $5 for a mast if you must, and Beezley's recommended tweaks for another $5. If you want add a coax amp for $18-35 (I do with great results). This is NOT expensive to start with. If this doesn't work well enough, then return it and go for the high priced spread.
For the extra 70. or so, the APS-9 is a much better deal, especially once you go to all the trouble mounting it, installing the rotor, etc.
It's not the gain, it's the directionality, front back ratio, and SWR you are getting by paying a bit more.
I'm sure you're right.In my case it would be massive overkill. I don't even need a rotator here, nor a mast.
However, were I so inclines I'd look at the other site where the guy did customize it for distance and directionality starting with the RS and for just a few bucks added his own elements and tested out great. Also, Beezley shows you how to do a combination of 2 such antennae, and that might work exceptionally well here.
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