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Sorry guys, I mixed 2 problems related to noise.
There are first the noise generated by beam vs quad, but I cannot estimate the noise level, excepting that the quad is more silent under high wind. The 5-10 dB less for the quad are related to the white noise. I explain. According a swedish OM, it appears also some kind of white electrical noise on a beam compared to a quad. The theory/argument is that the Yagi is more prone to picking it up due to its high impedance at the dipole ends. Quoted and translated from Swedish: "The noise I talk about is on eg. 20 m and 5-10dB above the threshold on a yagi but barely audible on a quad. It has always the same strength independent of the time of day, possibly a bit weaker at sunrise. The noise from static discharges are completely different. The noise I am talking about is more "white"." Quoting the list: "I have performed tests between Yagi/quad specailly on 20 meters. I have used a 5 el monoband yagi and a 6 el monoband quad. The difference is about 5-10dB. The direction seems to be irrelevant, the white noise is everywhere. " The origin of noise is unclear but thoughts are (and these are speculations): Perhaps the first skip of NVIS-noise from a town nearby? Or that the quad's liftoff angle is different that the yagi's and so picks up anything from another angle? Can someone confirm this better performing of the quad ? Thanks Thierry ON4SKY "Thierry" To answer me in private use http://www.astrosurf.com/lombry/post.htm wrote in message ... Hi, Before investing in a future antenna I have discussed on my site about antennas designs, quad vs yagi or log. http://www.astrosurf.com/lombry/antenna4.htm I would like to get more information from users. If you used both quad and ... |
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