[Antennaware] vertical with metal roof as groundplane

Guy Olinger, K2AV olinger at bellsouth.net
Fri Feb 27 20:20:46 PST 2009

Using the tin roof itself for the ground plane is rife with potential 
connectivity problems.

Back in my Washington DC just out of college days I lived in a row house 
block with parallel copper roofs couple hundred feet either direction up the 
street.  I mounted the antenna on a sewer vent pipe and put regular radials 
suspended a foot or so above the roof.  The results for that setup were 
excellent.  I used it on 40-10.  I was severely disappointed when I took the 
same physical setup and ran it just above sod at my suburban home a few 
years later.

Use your building as a ground screen underneath but not connected to your 
tuned radial system. Use a current block between the vertical/radial feed 
and the feed coax. Ground the coax shield to the roof on the shack side of 
the current block. Do not use the roof as an active part of the antenna.

73, Guy.

----- Original Message ----- 
From: "George Warnock" <george_warnock at hotmail.com>
To: <antennaware at contesting.com>
Sent: Friday, February 27, 2009 6:27 AM
Subject: [Antennaware] vertical with metal roof as groundplane

> Hello folks...am preparing the ground to build a workshop, when completed 
> it will be 40 foot long by 30 foot wide, there will be a box profile tin 
> roof, the pitch of the roof will be approx 20 degrees.There will be a 
> metal truss in the centre of the roof to support metal purlins and then 
> the roof its self....to me this sounds like a likely candiate to support a 
> "support" for a 40m  vert antenna and use the tin roof for a groundplane.I 
> would be interested in what you folks think of the idea, and perhaps some 
> one could see perhaps a way of taking even more advantage of the 
> situation...am thinking along the lines of phased verticals perhaps with 
> additional ground wires or antenna for 80m or 40/80....the only down side 
> I can see is there is a tower about 50 feet from where the shed is going 
> to be so that may have some interaction...the "mechanics" of bonding the 
> individual sheets of tin together to form a ground plane will be taken 
> care of during the build..
> reguards george
>        gi0vgl...
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