[TowerTalk] Metal Roof

Grant Saviers grants2 at pacbell.net
Thu Jan 11 12:26:59 EST 2018

What does "interferes with the 2 meter repeater" mean?

We could get in the ballpark SWR curves to prove an A4S tribander was 
assembled correctly for FD at about 60' out and 42' up from a 56 x 70 x 
14' all metal building.  That doesn't say much about the pattern, 
'tho.   I think a couple of wavelengths is a good goal.  My 40m Moxon 
seems to perform as modeled F/B at 91' up and 70' out from the same 
building, SWR is perfect to modeling.     A 4L SteppIR at 40' out and 
91' up from same building works very well (F/B, swr) 20 > 6m.

A 40' 3" irrigation pipe 80m top loaded vertical I had on a galvanized 
metal barn roof peak was awesome at 1550' above a prior Silicon Valley 
QTH.  Wind to 80mph.  Something you might consider for 80/160.

It is possible to model large conducting plates near antennas or as 
ground planes, but it is a lot of work and requires NEC4 IMO.

Grant KZ1W

on 1/11/2018 8:19 AM, Gilbert Kauffmann wrote:
> I live on top of Niles Hill  about 2,300 ASL  and the winds is unbelievable high...
> I lost part of my shingle roof twice and the insurance company dropped me.....
> Now, I have a metal roof, fantastic, no problem with 60 mph winds.....
> However, I have a 40 ft tower with a 2 meter repeater antenna.....It seems that the metal
> roof interferes with the 2 meter repeater....  Also, my 160 meter OCF pattern has changed
> a bit toward Northeast....
> As a summer project I have help to erect 2 towers  40 and 50 ft,  If more time 89 ft Self support....
> antennas,  M2 3 el 40 yagi....Mosley TA34XL,......2 stacked 105CAS....M2 6M7JHC
> Does anyone know how to figure how far the towers should be away from the house ?? It seems
> the metal roof  80 ft long has some interference of 2 meter and my  OCF dipole....
> Tnx  de Skip  K3CC
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