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[Antennaware] re vertical with metal roof as groundplane.

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Subject: [Antennaware] re vertical with metal roof as groundplane.
From: George Warnock <>
Date: Sun, 1 Mar 2009 18:12:05 +0000
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Hello there thanks to k2av guy and pete ny2r for contributing to 
the most interesting subject..I saw an opportunity arising with the building of 
this workshop to contribute to the efficency of my station, I knew there was a 
learning curve involved but did not realise how little I takes me a 
little while to interpet what I have been told, but because of the clear and 
consise manner it has been explained my knowledge has grown 
considerably...there are one or two points I would like to expand upon so I 
hope that guy k2av would be good enough to help out...guy my "need" as you 
describe is non hemispheric, so as you describe I will pull the two radials to 
opposite quadrants,  and will cut them to meet the impedance requirments....if 
you recall my roof structure is of the pitched or angled variety with a pitch 
of 20 degrees, to facilitate the opposite quadrants of interest to me, the 
radials will be following the pitch of the roof and dropping the 20 degrees, 
 is this a disadvantage? perhaps it does not matter when as you say the radials 
are only there to act as a current sink to complete the feed point 
connection,there is another factor perhaps worth considering here the building 
is 40 feet by 30 feet, the longer part being the "ridge" level or horizontal 
part, another thing concerning me and I have read different opinions on the 
subject is how high should the feed point be above the roof structure some folk 
say as close as possible, but another thought is, if above the roof somewhat 
the angle of the radials can be varied to effect feed point impediance... again 
this will proberbly not apply in this instinct is to try and take 
advantage of the situation I have with this proposed structure "workshop" and 
its metal roof, 40m seems to be ideal, but not having anything worth while for 
80m, I am wondering if a vertical covering two bands is feasible and what 
advantages or disadvantages there is in such a structure.

reguards to all george


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