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Roy Lewallen wrote:
Mike Coslo wrote: . . . I don't doubt that someone might come to a different conclusion, but I think my reasoning is pretty sound. I modeled an equal length version of this in 4nec, and it just doesn't work very well. OTOH, turn it into an OCF dipole, and it is a different story. . . How did you possibly determine what the balun input impedance was when terminated with the impedances the antenna presented on the various bands? You are correct, I couldn't. But what I got was enough to tell me that with the two sides of equal length, there wasn't much need to go any further. Cannot some antenna characteristics be modeled without the entire system in place? I'm no expert, so I'll ask the question: Is there some Balun that will make a 135 foot equal length antenna perform on 80-10 meters? How did you model the balun? It's almost certainly a "voltage" balun which will force common mode current onto the feedline when terminated with an asymmetrical load. Because of the common mode current, the outside of the feedline must be part of the model. Did you model the antenna with various lengths and orientations of feedlines? I don't believe that a valid model can be made of this type of antenna without knowing and accounting for the major imperfections of the balun, the common mode current it forces, and the feedline length and orientation for the particular installation. It isn't whether my model is exceptionally valid. I don't know what the balun is that they use, so that sense it doesn't matter anyhow. You would know much better the balun that would make this antenna work. I'm just looking at what is there, and by looking at both the context of the advertisement, references given for their other antennas and the like, I'm just saying that I suspect that that antenna is a OCF dipole. Their G5RV antennas do *not* have an L1 and L2 to designate length of the sides. If that antenna has an equal length side, it is the only one on the site that does. Yeah, I know they are not really G5RV's. In addition, is BuxCom going to try to sell a product that apparently doesn't work? I don't see any of the hype that tends to go along with the "magic" antennas we sometimes hear about All of the above just about convince me that the antenna in question is an OCF dipole, and that the description and image is a big typo. Others may take it at all at face value, disregard all the evidence to the contrary, and assume that the sellers are just trying to hoodwink a gullible public into buying a non-working product. That doesn't make sense to me. YMMV - 73 de Mike KB3EIA - |
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