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[TowerTalk] How Important is F/B?

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Subject: [TowerTalk] How Important is F/B?
From: (T. A. Russell)
Date: Thu, 26 Jun 1997 06:25:44 -0600
In my opinion,  Front-to-Back ratio is an overrated characteristic.

Like SWR, it IS something that can be easily measured, or at least
observed, by the user.  High F/B is usually attained by sacrificing
a little gain (usually on the order of 1 dB).

Before an ice storm destroyed my 2 element Mosley  Quad, I used 
it as a multiplier hunting antenna in contests.  I parked it due East
and could hear everything from Europe to South America off the front.
With only a moderate F/B ratio, I also heard and WORKED stations
(multipliers) in the Pacific off the back.  

When I replaced that Quad with a TH7 which exhibited a much higher
F/B ratio, I could barely hear the pacific stations off the back and had
to switch to another antenna to work them.

I recall hearing a story about W0ZV 's experiences on 20M using
a KLM monobander one year and the KT34XA the next.  Of course
the monobander had a much better(?) F/B than the KT34XA.  As I
heard it, Bill worked about 10 more multipliers the year he used 
the KT34XA with a "poor" F/B ratio.

On the WARC bands, I have around 300 countries per band, all worked
with DIPOLES  or  long wires which exhibit ZERO  F/B.

For contest antennas, I like about 10 dB of F/B.  That is enough to
tell there is directivity but still works about as well as a dipole off
the back.

Some contesters on the coasts like to have high F/B to attenuate
other USA stations when running over the water.  

A little less F/B might also help to keep your run frequency clear.

It comes down to personal preference.

de  Tom  N4KG

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