Topband: Upside down Vertical Antenna

[Jim Brown]

On Fri, 9 Nov 2007 11:28:23 -0800, Bob Eldridge wrote:

>Exploring further I found he
>lived at the top of an apartment building and the shield of his coax was
>connected to a 134 ft (downwards) vertical. 

Two observations. First, the antenna needs some low impedance radiator to 
act as a path for return current. Second, whatever carries that current 
will radiate -- it's RF current, so it radiates. In other words, the 
building was part of the antenna. 

When I lived in Chicago, the first function was fulfilled for my 
improvised 160M vertical by a wrought iron fence that ran around the 
front of my house. It worked pretty well in that regard, but it probably 
didn't radiate much. The 134 ft building probably radiated very well. :) 

73,

Jim Brown K9YC