Topband: Microwave Tower on 160 meters

[Jim Brown]

On Wed, 24 Dec 2008 19:32:52 -0500, Phil Theis wrote:

>I have a 180 foot self supporting tower that I use to get my microwave 
>antennas above the trees here in central PA.  I would like to get 
>something going for 160 off that tower. 

For a few years, I had use of a mountaintop QTH with a 150 ft AT&T tower 
(32 ft square at the base, 24 ft square at the top). The ground sloped off 
by about 30 ft to the NE. I hung a loaded dipole for 160 off that tower 
that also resonated on 80, and with a parallel element for 40M. The total 
length of the dipole was about 160 ft, with the top about 10 ft from the 
tower and the bottom about 10 ft off the ground. Coax came away from the 
antenna at not quite 90 degrees (toward the tower). 

That antenna worked VERY well. I ran CQ160CW one year and worked anything 
I could hear with 100 watts (and I could hear a lot).  Best DX was D4B 
(from near Sacramento). He called me. I also had a 40/30/20 version of 
this antenna on the other side of the tower. Based on some careful 
listening and switching, I'd estimate the F/B to be on the order of 6-8 
dB, with the tower acting as a parasitic element. There was no connection 
between my antenna and the tower. 

The sloping antenna that was being described to you was probably the one 
in the ON4UN book. It's been published a few other places. 

73,

Jim K9YC