Vic,
The OCFD is prone to Common Mode Current (CMC) problems.
If you have it over a metal roof and especially so close, expect lots of CMC
issues and you will possible lose a band or two.
I don't have experience over a metal roof, but on a SOTA operation, a 40m
OCFD mounted about 12 ft. above a metal fence lost operation on 40m. It's
SWR was very high. Moved it away from the fence and all was OK. And that
was just a wire fence.
73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)
May the Sunspots be with Us!
-----Original Message-----
From: TenTec <tentec-bounces+rick=dj0ip.de@contesting.com> On Behalf Of Vic
Klein via TenTec
Sent: 18 September 2020 14:20
To: tentec@contesting.com
Cc: Vic Klein <vhklein@ptd.net>
Subject: [TenTec] OT Antennas and metal roofs
I am considering replacing my asphalt shingles with a metal roof, but I
wondered about interaction with HF antennas. I have a 160m OCFD with the
feed point just 6ft above the roof, and another than attaches to a mast
about 4' above at the edge. Does anyone have experience with the effects of
changing to a metal roof?
73, =Vic=
WA4THR
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