Deflection is not as big of an issue as people might imagine. It's a bigger issue with composite poles, and almost a non-issue with wood.
This is counter intuitive, but if the tip of the pole moves a few feet side to side it doesn't change the angle of the antenna appreciably because that bend is spread over the length of the pole. The antenna moving sideways literally won't matter at all until it's really extreme. Swaying front to back matters more because the bending can eventually cause some elevation angle change on the antenna. On an 80' pole (70' AGL) you need something like 10 feet of front to back swaying (5ft from center each way) before the antenna has rotated 1 degree out of elevation alignment. You can get that much movement, but you're talking hurricane winds. We had at one time a couple dozen 11ghz links ranging from 5-15 miles at the top of 70' AGL fiberglass poles and never once did we lose signal to wind. Rain fade, yes, but if it was just wind without rain then it was never a practical issue. .....70mph winds are a once in a generation thing here though. We get 35-40mph sometimes, but not hurricane level winds. Your mileage may vary. -----Original Message----- From: AF <[email protected]> On Behalf Of Chris Fabien Sent: Friday, February 18, 2022 9:53 AM To: AnimalFarm Microwave Users Group <[email protected]> Subject: Re: [AFMUG] Utility Pole Rating I think for antenna mounting your limiting criteria may not be the pole strength related to it breaking but the stiffness related to antenna deflection during wind events mis-aligning your antennas. If you're only mounting APs it would be less of an issue than for a backhaul. On Wed, Feb 16, 2022 at 9:03 AM <[email protected]> wrote: > > Yeah, I think my frustration with this in the past was that what I really > wanted to know was "how many sq feet of antenna can I put on this pole", but > the sources are often more technical than that. Or if they've presented a > rule of thumb it's more about size of strand not size of antenna. > > I think we eventually arrived at the idea that a class 3 pole could carry > more antenna than we could realistically fit on it, so we bought class 3 and > didn't worry about it anymore. > > If the pole already has wireline utilities on it, then engineering the load > is part of the attachment application process and we're paying for that > whether the load is a wire or an antenna so figuring that out is built in to > the process. > > > -Adam > > > -----Original Message----- > From: AF <[email protected]> On Behalf Of Chuck McCown via AF > Sent: Wednesday, February 16, 2022 7:48 AM > To: AnimalFarm Microwave Users Group <[email protected]> > Cc: Chuck McCown <[email protected]> > Subject: Re: [AFMUG] Utility Pole Rating > > As I recall there is a chart or graph that boils it down to a class and > length to wind load. I remember having to determine the load of my planned > cable. The RUS had a great manual about it. > > Sent from my iPhone > > > On Feb 15, 2022, at 10:05 PM, Jason McKemie > > <[email protected]> wrote: > > > > So, as far as I can tell l, utility poles are rated by their moment > > capacity vs. wind loading. Am I interpreting this correctly? If so, > > is there a way to get an approximate wind loading number from the > > moment capacity? -- AF mailing list [email protected] > > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com
