Gary,
To clarify, I was referring to Field Strength, measured in Millivolts per
Meter, which is the standard expression. It takes 6 db to double the
measured signal strength, which is equivalent to one "S" unit.
3 db would translate to One Half of an "S" unit, still significant, but
not double.
Also, I used the term "within 3 db". Actually, the 2 times that I tried
this experiment, the results were 2.4 and 2.1 db improvement in Field
Strength when adding 90 (not 60) quarter wave radials to the existing 30.
The Field Strength was measured using a Potomac FIM 41 Field Strength meter
on a dozen monitor points at distances of 1 to 3 miles from the antenna.
I stated "within 3 db" to make sure that I was positively accounting for
measurement errors, including the meter's plus or minus 5 percent
certification, environmental factors, such as power lines, railroad tracks
and ground conductivity, as well as operator error.
73.
Mike
NM7X
Date: Mon, 7 Jun 2004 23:07:39 -0400
From: "Gary Hoffman" <garyhoffman@spacetech.com>
Subject: Re: [TenTec] Radials
To: <tentec@contesting.com>
Message-ID: <002201c44d05$c5a84110$6301a8c0@aa2iz>
Content-Type: text/plain; charset="iso-8859-1"
>
> The "point of diminishing returns" will vary relative to each person's
> perspective. On 160 meters, 30 (nominally) one quarter wavelength radials
> will yield a field strength at any ground wave reference distance that is
> within 3 db of 120 one quarter wavelength radials.
>
> Mike
> NM7X
Yes, indeed, it is most certainly a matter of perspective.
Now, my perspective is this: 3 dB is Double.
If I could double my signal, as inexpensively as burying 60 extra pieces of
the old wire I have laying around, I would most certainly do it in a
heartbeat.
Gary, AA2IZ
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