Topband: Influence on verticals by metal structures near feedpoint

[Thomas Hoeppe]

Hello everybody,

I have a question to the antenna experts here on the reflector. I have a balcony completly made of steel attached on the house. You walk on it from the 1st floor. One side is attached on the house, on the other side there are 2 metal posts supporting the whole structure. Parallel to one of the posts I installed a telescopic tower made of fiberglas. It uses several parallel tubings with high wall thickness....no fishing rod. I can erect it to 20m maximum (supported at 2 layers). I want to use it for the lower bands. Now I have 3 possibilities:

1. I begin with the vertical antenna on top of the balcony. I that case I could use elevated radials. The balcony is not connected to the radials.
2. I make the feedpoint down on the ground. The antenna wire is parallel to the supporting post and the balkony itself on the lower 3,5m, before the antenna wire is "free" in the air. I would make a ground system of radials in that case. This is the low-resistant part of the antenna, with maximum current. I am afraid of coupling a lot of power in the (grounded) balkony metal.
3. I start the wire on the balkony, and attach the wire system on ground at the lightning-protection post of the balcony. We could call it a "elevated feedpoint". The balcony is bringing the groundsystem up to the feedpoint and is also a part of it.

I hope I could describe it that you understand the problem with my poor English.

What do you think? 

Thanks for all comments.

Tom, DJ5RE