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
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