[TowerTalk] OCF and 160m?

[Jim Brown]

On Wed, 04 Oct 2006 16:23:33 +0000, Eugene Hertz wrote:

>I have two trees on my property. They are 195' apart. 

If you string a horizontal antenna between them, how high will it 
be?  This is a VERY important question. 

Second, you should plug this information into a simulation program 
called HFTA, written by N6BV and distributed with the latest ARRL 
Antenna Book. This program takes terrain elevation data from USGS 
maps (free on the internet) and predicts the vertical pattern for 
various heights of horizontally polarized antennas. It then allows 
you to plot that data with an overlay of the vertical angles 
needed to work various DX and state-side destinations. 

The main reason for doing this is to 1) figure out how well a 
horizontally polarized antenna will work for you at the heights 
you can build, and 2) which heights are best. Once you have that 
info, you can figure out whether a VERTICAL antenna with radials 
(like a T or the inverted L) might work better for you. 

For my QTH, the top-loaded vertical that I have improvised by 
using the feedline of an 80/40 dipole is definitely better on both 
80 and 160 than anything I could do with a horizontal dipole. My 
antenna is at roughly 70 ft. If you can do a decent radial system, 
any height greater than about 45 ft with a dipole or flattop as 
top loading is going to be very good on 80 and decent on 160, and 
the higher the better. It works on 40 as a vertical, but not 
nearly as well as it does as a dipole. 

For higher bands, I use different antennas. My 80/40 dipole is 
only about 90 ft long. In your space, you have room for one of 
those and either a 30M dipole or a 3-band fan dipole for 20/15/10 
in line with it!  

73,

Jim Brown K9YC