Towertalk
[Top] [All Lists]

## Re: [TowerTalk] FW: Antenna spacing on mast

 To: w6nws@arrl.net, km5vi@flukey.cc, towertalk@contesting.com Re: [TowerTalk] FW: Antenna spacing on mast TexasRF@aol.com Sat, 15 Sep 2012 08:53:11 -0400 (EDT) mailto:towertalk@contesting.com>
 ```Hi All, running this problem through a mast calculator program shows a wind survival of 93 mph with the following assumptions: 1.9" OD .145" wall water pipe yield strength of pipe 27ksi pipe length 48" antenna load 5 sq ft Changing the antenna load to 2 sq ft increase wind survival to 143 mph. 73, Gerald K5GW In a message dated 9/15/2012 6:32:45 A.M. Central Daylight Time, lknain@nc.rr.com writes: Don't forget about the moment generated by the antenna. Wind pressure of 100 mph is about 40 psf IIRC. That means an antenna at 4 feet that has a wind load of about 182 lbs would deform the pipe at the bottom of the 4 feet (based on your 750 psf figure and ignoring the wind load on the pipe itself). At 40 psf that works out to about 4.5 sq ft of antenna. If the pipe were longer the antenna size would be less for the same effect. 73, Larry W6NWS -----Original Message----- From: KM5VI Sent: Friday, September 14, 2012 5:57 PM To: towertalk@contesting.com Subject: [TowerTalk] FW: Antenna spacing on mast It would take a wind pressure of over 750 psf to bend a 4' section of 2" SCH 40 pipe to the point of permanent deformation. 750 psf is about 30 times as much pressure as would be generated by a 100 mph wind. Strength-wise it would be no problem for a vhf antenna at this length. Interference-wise, the VHF antenna is really too small to affect the HF antenna even at close wavelength. At VHF, 4 ft is substantially enough wavelength away that the HF antenna that it should not adversely affect the VHF performance. KM5VI -----Original Message----- From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of David Thompson Sent: Friday, September 14, 2012 2:21 PM To: Michael Zeglen; towertalk@contesting.com Subject: Re: [TowerTalk] Antenna spacing on mast Please don't use Sch 40 water pipe even for a VHF antenna. Exposing 4 or more feet increases the chance of it bending in the wind. Water pipe strength is a flow inside not outside wind strength. Dave K4JRB ----- Original Message ----- From: "Michael Zeglen" To: Sent: Friday, September 14, 2012 2:42 PM Subject: [TowerTalk] Antenna spacing on mast > > > > > Want to mount my 2m - 440 small beam antenna above my Pro57B. How far > shouuld I space it or or does it really matter as long as there is 3 - 4 > feet spacing. I realize the more the better. What do you suggest? What is > good rule to follow. Sched 40 pipe is NO problem my son is a plumber! > _______________________________________________ > > > > _______________________________________________ > TowerTalk mailing list > TowerTalk@contesting.com > http://lists.contesting.com/mailman/listinfo/towertalk > _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] FW: Antenna spacing on mast, KM5VI Re: [TowerTalk] FW: Antenna spacing on mast, TexasRF <= Re: [TowerTalk] FW: Antenna spacing on mast, Joe Subich, W4TV Re: [TowerTalk] FW: Antenna spacing on mast, k2qmf Re: [TowerTalk] FW: Antenna spacing on mast, Joe Subich, W4TV