For the first time in many years I have been listening a lot on the low
bands (160/80/40). It seems there is much more background noise than when I
was in my teens, but that may be my selective memory at work. I am in the
far suburbs trying to use a half-sloper and an inverted V -- both with the
peak at about 53 feet. I think most of the noise is "natural" (except for a
15Khz harmonic every now and then.)

I started reading about small loops for receiving on 160 and 80. In
particular I have been reading about:

(1) the 4-turn loop on 4-foot cross arms (W1FB),
(2) the 4-turn coax loop (in a 9-inch diameter) (W1FB),
(3) an 18-inch ferrite rod unit described by G2BZQ

All of these were described as better receiving antennas "in the house" than
the authors' more conventional outside antennas. W1FB thought the 9-inch
loop was better than the 4-foot unshielded loop and apparently did not think
much of ferrite-stick antennas.

What is the experience of those on this newsgroup? Are these antennas
really better (in the house, and even in the basement) than conventional
outdoor antennas? Are they significantly better when used outside and
perhaps elevated a bit? I realize they are inconvenient because they must
be tuned even for small frequency changes. It seems they are very
directional for nulls but fairly broad for other responses. Is the same loop
good for 160 and 80 (and maybe even 40)?

Bill
W2WO

I found this same situation when I went to get on low band after 40 years
away from it.

I found that what sounded like natural background noise was not natural.

With a suggestion from a ham in Wisconsin, I found several insulators on
power poles near my home arcing. You can find these poles with a simple
battery powered am radio. Go back at night after you find a noisy one and
use binoculars to see the actual arcing. Now you can call the power company
and point out the bad insulator. This worked for me.

I have a 60 foot random wire antenna and it is very quiet now. Putting up a
loop will not fix the noisy insulators.
BTW these insualtors arc more in damp weather than when it is dry.

Michael


"Bill Ogden" wrote in message
...
For the first time in many years I have been listening a lot on the low
bands (160/80/40). It seems there is much more background noise than when
I
was in my teens, but that may be my selective memory at work. I am in the
far suburbs trying to use a half-sloper and an inverted V -- both with the
peak at about 53 feet. I think most of the noise is "natural" (except for
a
15Khz harmonic every now and then.)

I started reading about small loops for receiving on 160 and 80. In
particular I have been reading about:

(1) the 4-turn loop on 4-foot cross arms (W1FB),
(2) the 4-turn coax loop (in a 9-inch diameter) (W1FB),
(3) an 18-inch ferrite rod unit described by G2BZQ

All of these were described as better receiving antennas "in the house"
than
the authors' more conventional outside antennas. W1FB thought the 9-inch
loop was better than the 4-foot unshielded loop and apparently did not
think
much of ferrite-stick antennas.

What is the experience of those on this newsgroup? Are these antennas
really better (in the house, and even in the basement) than conventional
outdoor antennas? Are they significantly better when used outside and
perhaps elevated a bit? I realize they are inconvenient because they must
be tuned even for small frequency changes. It seems they are very
directional for nulls but fairly broad for other responses. Is the same
loop
good for 160 and 80 (and maybe even 40)?

Bill
W2WO

Bill Ogden wrote:
For the first time in many years I have been listening a lot on the
low
bands (160/80/40). It seems there is much more background noise than
when I
was in my teens, but that may be my selective memory at work. I am
in the
far suburbs trying to use a half-sloper and an inverted V -- both
with the
peak at about 53 feet. I think most of the noise is "natural"
(except for a
15Khz harmonic every now and then.)

I started reading about small loops for receiving on 160 and 80. In
particular I have been reading about:

(1) the 4-turn loop on 4-foot cross arms (W1FB),

Mine is closest to this one...Mine is a 44 inch per side diamond, using
5 turns.

(2) the 4-turn coax loop (in a 9-inch diameter) (W1FB),

I have to wonder how he is tuning 4 turns on a 9 inch form?

Seems it would tune quite high in freq...

I have a 16 inch circular loop, but it takes about 12 turns to tune
MW..

(3) an 18-inch ferrite rod unit described by G2BZQ

Worst of the bunch, no doubt....

All of these were described as better receiving antennas "in the
house" than
the authors' more conventional outside antennas. W1FB thought the
9-inch
loop was better than the 4-foot unshielded loop and apparently did
not think
much of ferrite-stick antennas.

What is the experience of those on this newsgroup? Are these
antennas
really better (in the house, and even in the basement) than
conventional
outdoor antennas?

Depends on the use, and also depends on the source of the noise.
If the noise source is local, they can work very well to null that
noise. If the noise is just general atmospheric noise, the results
won't
be as good. Yes, the nulls are very sharp.

Are they significantly better when used outside and
perhaps elevated a bit?

I've heard of people elevating, but myself, I'm not really convinced
it makes any difference. I keep mine on the floor, here in the shack
on stands, so I can rotate them. They work fine , even on the ground.

I realize they are inconvenient because they must
be tuned even for small frequency changes. It seems they are very
directional for nulls but fairly broad for other responses. Is the
same loop
good for 160 and 80 (and maybe even 40)?

Ok for 160, but not really sure about the other bands. I use mine more
for MW use than anything...But mine does work 160m. The *best* time
for
a loop is actually in the daytime for MW ground wave use. They work
great
for that. They do help at night a bit as far as nulling some noise, or
unwanted stations, but the nulls on a skywave signal as not near as
deep
as for ground wave. To have a better idea if it's worth a try, will
probably depend on the source of your noise. If it's a local source,
could be worth a try. You can null that source down to nearly nothing..
But if you have multiple sources of noise, the results won't be as
good.
A loop won't be in the leaque of say a beverage or whatever, for say
160m dx...
MK

Very approximately -

To compare one loop with another, at a given frequency, the receiving
sensitivity of small loops is very simply proportional to the area enclosed
and tends to decrease as the number of turns.

Best to use very thick wire with a single turn loop (as with magloops) and a
tuning capacitor to suit. Multi-turn loops are used ONLY because of
availability of paractical sizes of tuning capacitors.

With a multi-turn ferrite rod antenna of given dimensions, sensitivity
increases roughy proportional to the permeability of the core material but
decreases according to loss in the core. Permeabilty increases the
effective area enclosed. So use an HF core material - not one intended for
VLF power transformers.

Ferrite rod receiving antennas appear to do very well ONLY because medium
and long-wave broadcast transmitters are generally high power. They are high
power because of the poor sensitivity of very small (in comparison with a
wavelength) receiving antennas.
----
Reg.

Thank you for the comment about power line noise. Fortunately I live in an
area with underground power. There can still be problems, of course, but
single-point power arcing *usually* has a fairly distinctive sound.

Several direct replies to me indicate that other people have had the same
experience that low-band noise is greater now than in the good old days.
Perhaps it is simply the cumulative effect of many small sources.

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?)

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.

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.

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?
Subjective comparisons are fine if they are based on real experiences.

Bill
W2WO


"flashback" wrote in message
...
I found this same situation when I went to get on low band after 40 years
away from it.

I found that what sounded like natural background noise was not natural.

With a suggestion from a ham in Wisconsin, I found several insulators on
power poles near my home arcing. You can find these poles with a simple
battery powered am radio. Go back at night after you find a noisy one and
use binoculars to see the actual arcing. Now you can call the power
company
and point out the bad insulator. This worked for me.

I have a 60 foot random wire antenna and it is very quiet now. Putting up
a
loop will not fix the noisy insulators.
BTW these insualtors arc more in damp weather than when it is dry.

Michael


"Bill Ogden" wrote in message
...
For the first time in many years I have been listening a lot on the low
bands (160/80/40). It seems there is much more background noise than
when
I
was in my teens, but that may be my selective memory at work. I am in
the
far suburbs trying to use a half-sloper and an inverted V -- both with
the
peak at about 53 feet. I think most of the noise is "natural" (except
for
a
15Khz harmonic every now and then.)

I started reading about small loops for receiving on 160 and 80. In
particular I have been reading about:

(1) the 4-turn loop on 4-foot cross arms (W1FB),
(2) the 4-turn coax loop (in a 9-inch diameter) (W1FB),
(3) an 18-inch ferrite rod unit described by G2BZQ

All of these were described as better receiving antennas "in the house"
than
the authors' more conventional outside antennas. W1FB thought the
9-inch
loop was better than the 4-foot unshielded loop and apparently did not
think
much of ferrite-stick antennas.

What is the experience of those on this newsgroup? Are these antennas
really better (in the house, and even in the basement) than conventional
outdoor antennas? Are they significantly better when used outside and
perhaps elevated a bit? I realize they are inconvenient because they
must
be tuned even for small frequency changes. It seems they are very
directional for nulls but fairly broad for other responses. Is the same
loop
good for 160 and 80 (and maybe even 40)?

Bill
W2WO

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