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Old February 14th 05, 10:29 PM
 
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Bill Ogden wrote:


Implied in my question about small receiving loops is whether they

are less
sensitive to this type of noise. (A dipole is often less sensitive

to noise
than a vertical when storms are around; is there a somewhat similar

noise
rejection effect with small loops?)


No. Actually, I don't even agree that a dipole is any quieter than
a vertical. It just depends on the polarization of the noise which
is best...You'll get about a 20 db attenuation of any signal, if the
polarization is 90 degrees out from another antenna....


I realize that a small loop will produce lower level output than a

larger
loop (or other antenna) but, provided the S/N is good then either the
receiver gain or a front end amplifier should take care of the level.


There is no magic noise reduction using a small loop in general. But
you will see a tighter bandwidth compared to a larger antenna, and that

can act to reduce some noise. The Q will depend on the dia of the wire,
etc..
The real advantage to a small loop is it's sharp nulls, and the ability
to set it up to be easily turned. I suppose you could use very small
dipoles,
or verticals as the elements, but I don't see any change in s/n between

them. Naturally, the verticals would need some kind of phasing device
to
steer...You could turn the mini dipole indoors I suppose..."pre-amp
needed
I would think". But I don't know which would have the sharper nulls,
the
small dipole, or the small loop. In theory, I don't think should be
that
much difference...A larger small loop does have a better s/n ratio than
a
smaller, small loop, but you have to be in a quiet QTH to take
advantage
of it...IE: the lower the atmospheric and local noise, the more
advantage
to a larger loop. If the noise is high, IE: summer, often the smaller
loops work about as well as the larger ones...

I am not attempting to compare a loop with a Beverage or other exotic
antennas. I am attempting to compare it with a relatively low dipole

or a
simple vertical.


Well, if you mean full size low dipoles, and verticals, of course, the
nulls on the small loop would be much better, and more useful as far as

nulling a noise source.

Thus far, replies indicate that basement operation is not very

practical and
that elevation does not help much.
Does anyone have A:B comparisons with simple dipoles and verticals?


Sure...Do it all the time.....If I'm on MW, I prefer
the small loop over any of the usual wire antennas...
On 160, depends...There, I actually listen on my transmit antenna
more than the small loops...IE: DX...DX will often come in better on
a vertical, than the small loops, I think just due to the
polarization...
My small loops are horizontal...IE: diamond, fed at the bottom...
I have an inv L, and also a top loaded vertical on 160, so it's
probably not unusual to hear some dx better on those, than the loop.
I also have a Z dipole on 160....
My loops are mainly for MW and LW....On 160, it's a toss which is
best...The loop is often good for ragchew listening...
MK

 
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