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## Re: [TowerTalk] H frame for 10 or 15m

 To: towertalk@contesting.com Re: [TowerTalk] H frame for 10 or 15m Jay Kesterson K0GU Mon, 15 Aug 2011 19:36:53 -0600 mailto:towertalk@contesting.com>
 On 8/15/2011 1:30 PM, Stein Roar LA6FJA-K3RAG wrote: > Hi > > does anyone have ideas sizes for a H frame for 4-5 el yagies for 10 m and 15m > ? > is it 1/2 wl , 3/4 wl or 1 wl spacing ?? > > I saw one from http://www.arraysolutions.com/Users/h2a.jpg Arraysollution > from PY5EG > > > 73 LA6FJA Rag Your best bet if possible is to model the antennas and look at the gain compared to one antenna and the patterns. The wider the horizontal spacing the bigger your first side lobes. That may not be a problem if you can't stack them very far apart horizontally. But if you can stack them far apart then you need to possibly chose a bit more gain vs a better pattern. I have a model of a Hy-Gain 105CA (24' boom) for my antenna modeling program. And I am a bit bored so here goes... Just to get the feel for how the horizontal and vertical stacking distance affects the antenna I first model only two antennas. Single 105CA = 8.24 dbd Two 105CAs stacked vertically spaced 20 feet = 10.50 dbd 24 feet = 10.84 dbd 28 feet = 11.12 dbd 32 feet = 11.30 dbd 36 feet = 11.35 dbd As far as vertical spacing is concerned somewhere around 24-28 feet looks pretty good. There is less interaction between the antennas as the stacking distance gets larger. More than 28 feet produces little advantage and a fair amount of extra wind load.. Two 105CAs stacked horizontally spaced 20 feet = 9.72 dbd (first side lobes are ~37 db down) 24 feet = 10.27 dbd (first side lobes are ~30 db down) 28 feet = 10.66 dbd (first side lobes are ~22 db down) 32 feet = 10.95 dbd (first side lobes are ~16 db down) 36 feet = 11.11dbd (first side lobes are ~16 db down) This will depend on how much you value gain compared to pattern. I would likely choose 28 feet vertically and 24 or 28 feet horizontally. I like a nice tight pattern. Not a lot of advantage beyond 28 feet. 4x H-Frame array of 105CAs spaced 20' high - 20' wide = 12.00 dbd 20' high - 24' wide = 12.46 dbd 24' high - 24' wide = 12.71 dbd 28' high - 24' wide = 13.09 dbd 28' high - 28' wide = 13.53 dbd The first azimuth side lobes are essentially the same value on the 4 stack as the 2 horizontal stack. This model is based on a 24 foot boom 10m yagi. A shorter boom will require a bit less spacing and a longer boom more spacing. 73, Jay K0GU _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk
 Current Thread [TowerTalk] H frame for 10 or 15m, Stein Roar LA6FJA-K3RAG Re: [TowerTalk] H frame for 10 or 15m, Rick Karlquist Re: [TowerTalk] H frame for 10 or 15m, DF3KV Re: [TowerTalk] H frame for 10 or 15m, Gene Fuller Re: [TowerTalk] H frame for 10 or 15m, Jay Kesterson K0GU <= Re: [TowerTalk] H frame for 10 or 15m, Stein Roar Brobakken