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Being confused with two designs of Collinear Antenna
Hi,
I have read about collinear antennas within the two web sites below: http://www.guerrilla.net/reference/a...ollinear_omni/ http://wireless.gumph.org/articles/homemadeomni.html I have made the first one. But before testing it, I have noticed that there is a very essential difference between them. In the first design there is a short circuit between the central conductor and the shielding in all segments as the final 1/4 wavelength segments is a short circuit itself. But in the second design, there is a strict advice that check the complete antenna before using it in order to prevent any short cross connection between the central connector and shielding. Can anyone describe me what design wil actually work? and if both will work what is the reason of that difference? Very sincerely, Farzad |
#2
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Tho, both will work, the correct one, from my experience with useing DB
Products "Green Hornet" series antennas, is the one with the 1/4 wave/shorted piece of coax to the 1/4 wave stinger. Ans as a aside, in vhf service, check for a dead short to the antenna (they flex in the wind, -if you see it go open, or high resistance, when the wind blows, needs replaceing) one thing NOT mentioned, in either of these sites, is the application of Ground Plane radials , however, again, the shorted antenna has a 1/4 wave decoupling sleeve, which should do the same as the radials! All in All, I'd go with the shorted one- and a caution: the pattern of these is VERY NARROW- and close to the HORIZON (omni-directional) - look like drop a doughnut over the antenna! want to mount this as straight up-down (verticle) as possible for max range! As info, Jim NN7K farzad wrote: Hi, I have read about collinear antennas within the two web sites below: http://www.guerrilla.net/reference/a...ollinear_omni/ http://wireless.gumph.org/articles/homemadeomni.html I have made the first one. But before testing it, I have noticed that there is a very essential difference between them. In the first design there is a short circuit between the central conductor and the shielding in all segments as the final 1/4 wavelength segments is a short circuit itself. But in the second design, there is a strict advice that check the complete antenna before using it in order to prevent any short cross connection between the central connector and shielding. Can anyone describe me what design wil actually work? and if both will work what is the reason of that difference? Very sincerely, Farzad |
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