[Antennas] Re: Elavated Ground planes

[Charles Greene]

Mick,

You are lucky to have a large iron roof as a ground plane.  Forget about 
getting a good RF ground to earth ground.  Such a connection would only add 
a lossy earth ground in parallel to your good metal roof.  Any current 
flowing in the lossy earth ground would only cause losses.  Just connect 
the antenna base ground to earth ground consisting of a copper plated 
ground rod using a single heavy ground wire like used in electrical 
service, for lightning protection.  Here, you want a low resistance DC 
ground.  Don't worry about any distortion of the pattern caused by the 
rectangular pattern of the roof.  It will be minor, and you probably will 
not notice it.  There's not much you can do to correct it anyway.

At 11:46 AM 11/1/2002 +1000, Mick wrote:
>Hi guys,
>     As I have a small yard around my house l am looking at building a multi
>band trap vertical and mounting it on the house roof (with nylon guy  wires)
>and was going to use the large Iron roof as a ground plane. The roof is
>rectangular in shape so would think that the radiation patton will also be
>elongated. A question  I would like to ask the list is should I run wires
>from the roof down to earth points around the house ,and if so how many or
>can I just rely on the 4 metal down pipes ( that carry  the water from the
>roof to the drainage system) to serve the same purpose.
>Thanks Michael Harley,
>Curator "The Radio Shack", Caboolture Historical village, Brisbane
>Australia.


73, Chas, W1CG
K2 #462