If the width of the blade where it intercepts the LOS is as wide as the first fresnel zone I would expect big problems. But if you just have blade tips encroaching on the upper number fresnel zones or a portion of the first fresnel zone I don’t think it would be a problem.
From: Steve Jones Sent: Friday, February 28, 2020 5:42 PM To: AnimalFarm Microwave Users Group Subject: [AFMUG] freznel impact calculator I have a 3 link path i need to turn up in 11ghz. we drove the path yesterday. 2 legs are golden. one however is problematic, ive got two wind turbines that are in or just outside the fresnel. If it were one, id probably be inclined to risk the impact if there was just one turbine, but two is iffy without some good maths to support it. The path is 5.5 miles the first turbine is 3.64 mile the second is about 4.69 miles Fresnel is about 25' radius at that distance max if the calculator is right the first turbine is maybe 100' from boresite the second is probably 150' These arent our normal turbines, these the the bad motherfucker turbines, so the blades are like a million feet long, actually IIRC theyre 224' on something like a 400' pedestal. I need to pull the specs again on those and get better than google earth GPS coordinates on the potential end points, and some better actual heights that brings be to the question, how do i calculate a partial fresnel obstruction with a radius like the blade pattern. I figure boresite view with a 50' circle would give me worst case fresnel, then i just draw the arc of the turbine path into that as an obtruction for each maybe just shade the polygon it create as a complete obstruction. So once i have that info, what tool can i put it into to calculate the impact? everything we use just has an obstruction height. Would i be able to just take the distance from edge of fresnel into the furthest point of the polygon? Would I need to calculate more loss than that? Im planning on sticking a 5ghz link up anyway pending licensing, so i assume i can just extrapolate the loss from that -------------------------------------------------------------------------------- -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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