To: <topband@contesting.com>
> Date: Sun, 10 May 1998 16:17:38 -0400 (EDT)
> From: K1ZM <K1ZM@aol.com>
Hi Jeff,
Here's where all this silly folklore about loop antennas comes back
to hurt us.
> They will try a short beverage or a magnetic loop perhaps tomorrow night - I
> explained the loop to George, and I think he got it's design okay - if they
> can come up with an 800 pf trimmer cap.
I don't know why DXpeditions waste time with so called "magnetic
loops". The Spratly group did the same thing.
The signal from a lightning bolt, once you are a few miles from the
bolt, is exactly the same ratio of electric to magnetic fields as a
signal from a transmitter.
The "magnetic loop", once you are several loop diameters from
the so called "magnetic loop" has exactly is exactly the same ratio
of electric to magnetic field response as any other antenna.
The only way to discriminate against QRN or any non-nearfield noise
is with a directive antenna. Either a EWE, or a Beverage. A single
loop is a waste of time.
Unless they have something arcing a few feet from the antenna causing
noise that by a stroke of luck happens to be near-field electric
field dominant, they might as well just use an attenuator pad on
their TX antenna as use a loop.
73, Tom W8JI
w8ji.tom@MCIONE.com
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|