Topband: relay-switched inverted L for 40/80/160

[GEORGE WALLNER]

On Tue, 29 Sep 2009 10:30:19 -0400
  Guy Olinger K2AV <olinger at bellsouth.net> wrote:
> A 160 meter inverted L can be used quite successfully on 
>80 and 40.

Guy,

You are correct to say that the 160 inv will have a high 
impedance feed point on 80 which is not as difficult to 
feed as some may think.

However, the 160 inv L on 80 meters is a poor DX antenna. 
It has mostly high angle radiation. NEC modelling will 
show that. We've also found that out the hard way on the 
VK9WWI DXpedition, where we used a 160 m inv L for 80 (fed 
via a tuner). The antenna performed very poorly for NA and 
EU (but the JA-s heard us well). Eventually we realized 
that if we lowered the horizontal wire and brought it to 
the antenna base for 80 meter operation, performance would 
improve. For the VK9GMW Mellish Reef operation we designed 
an antenna that overcame this problem. It had part of the 
"horizontal" wire bent down and grounded for 80 meter 
opration. As many will testify, it worked. (The 
description of the antenna is available as a downloadable 
PDF document at 
http://vk9gmw.com/documents/VK9GMW_ANTENNA.pdf )

73,

George
AA7JV