Yes, that is an advantage. Everytime someone asks a question about a receive
only antenna on this newsgroup, there are always many responses saying to
just put up a piece of wire and run it strait to your radio. That will work,
assuming that you live out in the middle of nowhere, have no neighbors and
have no electrical appliances. For the rest of us, noise is a consideration
and more thought needs to be put into an antenna system.

"Kees" wrote in message
...

That's indeed what it is:
a very low-noise antenna.

Look at : http://members.home.nl/rita.kees/t2fdmake.html

for my "version ".

"CW" no adddress@spam free.com wrote in message
...
Yes, that is an advantage. Everytime someone asks a question about a
receive
only antenna on this newsgroup, there are always many responses saying to
just put up a piece of wire and run it strait to your radio. That will
work,
assuming that you live out in the middle of nowhere, have no neighbors and
have no electrical appliances. For the rest of us, noise is a
consideration
and more thought needs to be put into an antenna system.



How does the antenna differentiate between "noise" and a valid signal?

(Perhaps these are going to be the solution to BPL.)

Pete

In article sBEDc.1168$Rr2.4@lakeread03,
" Uncle Peter" wrote:

"CW" no adddress@spam free.com wrote in message
...
Yes, that is an advantage. Everytime someone asks a question about
a receive only antenna on this newsgroup, there are always many
responses saying to just put up a piece of wire and run it strait
to your radio. That will work, assuming that you live out in the
middle of nowhere, have no neighbors and have no electrical
appliances. For the rest of us, noise is a consideration and more
thought needs to be put into an antenna system.

How does the antenna differentiate between "noise" and a valid
signal?

Antennas are not intelligent agents able to differentiate between noise
and a broadcast signal. If the noise signal is generated a long
distance from the antenna it will be received right along with
broadcast signals. The only advantage some antennas would have here is
its reception pattern where the antenna could be orientated to be
relatively insensitive in the direction of the noise signal. This
generally is not helpful for short wave signals though because they are
generally too spread out directionally instead of looking like a point
source to take advantage of antenna nulls. Another problem for most
people is the fact that they cannot get the antenna up high enough for
it to exhibit its directional characteristics to a great degree.

A local noise is another matter greatly affecting many peoples
reception of short wave signals since many electronic devices around
the home and neighbor¹s homes generate noise. Here the type of antenna,
how it is connected to the receiver, and where it is located on the
user¹s property makes a huge difference on what may be heard.

Fundamentally, you want the entire antenna system to reject common mode
noise since to a local antenna this is the mode in which, the local
noise will couple to the antenna. You will want to use an antenna that
is balanced (Hertzian) instead of unbalanced (Marconi). You might also
want to consider using an antenna type that responds more to the
magnetic field component of the radio wave instead of the electric.
These two suggestions encompass the fact that most of the local noise
energy reaching and coupling to the antenna is a common mode electric
field and since the far field broadcast signals you want to receive is
composed of both electric and magnetic the later will be enhanced at
the expense of the former.

The connection from radio to antenna is best shielded so you would use
coax. You could use a balance line but they are harder to acquire, use,
and still will not work as well as coax shielding against local noise.

The antenna would be located as far from the majority of local noise
sources as possible on the property. Distance reduces the coupling to
local noise sources.

--
Telamon
Ventura, California

"Telamon" wrote in message
...
In article sBEDc.1168$Rr2.4@lakeread03,
" Uncle Peter" wrote:

How does the antenna differentiate between "noise" and a valid
signal?



SNIP


Fundamentally, you want the entire antenna system to reject common mode
noise since to a local antenna this is the mode in which, the local
noise will couple to the antenna. You will want to use an antenna that
is balanced (Hertzian) instead of unbalanced (Marconi). You might also
want to consider using an antenna type that responds more to the
magnetic field component of the radio wave instead of the electric.
These two suggestions encompass the fact that most of the local noise
energy reaching and coupling to the antenna is a common mode electric
field and since the far field broadcast signals you want to receive is
composed of both electric and magnetic the later will be enhanced at
the expense of the former.

The connection from radio to antenna is best shielded so you would use
coax. You could use a balance line but they are harder to acquire, use,
and still will not work as well as coax shielding against local noise.

The antenna would be located as far from the majority of local noise
sources as possible on the property. Distance reduces the coupling to
local noise sources.

--
Telamon
Ventura, California

You'd also have to decouple the coax shield from the antenna to
prevent signals or noise from carried on the outside of the shield
common-mode fashion from being coupled back into your
remotely located antenna.

Pete

" Uncle Peter" wrote in message
news:HVKDc.1192$Rr2.241@lakeread03...

"Telamon" wrote in message
...
In article sBEDc.1168$Rr2.4@lakeread03,
" Uncle Peter" wrote:

How does the antenna differentiate between "noise" and a valid
signal?



SNIP


Fundamentally, you want the entire antenna system to reject common mode
noise since to a local antenna this is the mode in which, the local
noise will couple to the antenna. You will want to use an antenna that
is balanced (Hertzian) instead of unbalanced (Marconi). You might also
want to consider using an antenna type that responds more to the
magnetic field component of the radio wave instead of the electric.
These two suggestions encompass the fact that most of the local noise
energy reaching and coupling to the antenna is a common mode electric
field and since the far field broadcast signals you want to receive is
composed of both electric and magnetic the later will be enhanced at
the expense of the former.

The connection from radio to antenna is best shielded so you would use
coax. You could use a balance line but they are harder to acquire, use,
and still will not work as well as coax shielding against local noise.

The antenna would be located as far from the majority of local noise
sources as possible on the property. Distance reduces the coupling to
local noise sources.

--
Telamon
Ventura, California

You'd also have to decouple the coax shield from the antenna to
prevent signals or noise from carried on the outside of the shield
common-mode fashion from being coupled back into your
remotely located antenna.

Pete

Quite true.

Telamon wrote:

A local noise is another matter greatly affecting many peoples
reception of short wave signals since many electronic devices around
the home and neighbor¹s homes generate noise. Here the type of antenna,
how it is connected to the receiver, and where it is located on the
user¹s property makes a huge difference on what may be heard.

Fundamentally, you want the entire antenna system to reject common mode
noise since to a local antenna this is the mode in which, the local
noise will couple to the antenna.

Yes!

You will want to use an antenna that
is balanced (Hertzian) instead of unbalanced (Marconi).

With an unbalanced antenna you must take more care to keep common mode
out of the feed system. It is not terribly hard, however, to reduce
common mode coupling to negligible levels, even with an unbalanced
antenna (see
http://www.anarc.org/naswa/badx/ante...e_antenna.html). One
may want an unbalanced system for other reasons. A balanced dipole close
to the ground generally has a poor vertical radiation pattern, while an
inverted-L is much better.

You might also
want to consider using an antenna type that responds more to the
magnetic field component of the radio wave instead of the electric.
These two suggestions encompass the fact that most of the local noise
energy reaching and coupling to the antenna is a common mode electric
field and since the far field broadcast signals you want to receive is
composed of both electric and magnetic the later will be enhanced at
the expense of the former.

This claim is widely made in the hobbyist literature, but I've never
seen any measurements to back it up. I've tried to check it myself, and
found the opposite: close to modern sources of EMI, the field tends to
be predominantly magnetic. You have to be very close the source to see
any effect at all: beyond ~0.1 wavelength induction balances the field
pretty effectively.

The connection from radio to antenna is best shielded so you would use
coax. You could use a balance line but they are harder to acquire, use,
and still will not work as well as coax shielding against local noise.

The antenna would be located as far from the majority of local noise
sources as possible on the property. Distance reduces the coupling to
local noise sources.

Yes!

-jpd

In article ,
John Doty wrote:

Telamon wrote:

Snip

This claim is widely made in the hobbyist literature, but I've never
seen any measurements to back it up. I've tried to check it myself,
and found the opposite: close to modern sources of EMI, the field
tends to be predominantly magnetic. You have to be very close the
source to see any effect at all: beyond ~0.1 wavelength induction
balances the field pretty effectively.

First off I did not realize this was cross posted so this is my last
post to this thread.

I'm not not regurgitating hobbyist claims but my experience in this
matter. Although 0.1 wavelength is more than enough to cover a urban
lot and your neighbor at short wave frequencies theory does not do
justice to a non homogenous environment we all live in. Most electronic
noise generators do not have efficient antennas attached to them where
the environment easily distorts the electric fields. I have repeatedly
experienced predominantly voltage common mode coupling of local noise
sources. Without exception mitigation methods against voltage common
mode noise were always successful and current mode antennas always
picked up less local noise.

--
Telamon
Ventura, California

In article telamon_spamshield-39A0DB.00324028062004
@news.sf.sbcglobal.net, lid
says...
In article ,
John Doty wrote:

Telamon wrote:

Snip

This claim is widely made in the hobbyist literature, but I've never
seen any measurements to back it up. I've tried to check it myself,
and found the opposite: close to modern sources of EMI, the field
tends to be predominantly magnetic. You have to be very close the
source to see any effect at all: beyond ~0.1 wavelength induction
balances the field pretty effectively.

First off I did not realize this was cross posted so this is my last
post to this thread.

I'm not not regurgitating hobbyist claims but my experience in this
matter. Although 0.1 wavelength is more than enough to cover a urban
lot and your neighbor at short wave frequencies theory does not do
justice to a non homogenous environment we all live in. Most electronic
noise generators do not have efficient antennas attached to them where
the environment easily distorts the electric fields. I have repeatedly
experienced predominantly voltage common mode coupling of local noise
sources. Without exception mitigation methods against voltage common
mode noise were always successful and current mode antennas always
picked up less local noise.



My main problems with noise have been the next door neighbors dimmer and
the transformer that threw out hash galore and took the electric company
about 2 years to fix. When it rained, or was cold enough for dew to
form, it was like a really annoying buzzer from about 0 to 10 MHZ. I was
overjoyed the night it blew up. It was "on the list" due to my nagging
them, but lightning did the job...

BDK

For your information:
You are posting this hole trhead on two dutch newsgroups!


Telamon a écrit
In article ,
John Doty wrote:

Telamon wrote:

Snip

This claim is widely made in the hobbyist literature, but I've never
seen any measurements to back it up. I've tried to check it myself,
and found the opposite: close to modern sources of EMI, the field
tends to be predominantly magnetic. You have to be very close the
source to see any effect at all: beyond ~0.1 wavelength induction
balances the field pretty effectively.

First off I did not realize this was cross posted so this is my last
post to this thread.

I'm not not regurgitating hobbyist claims but my experience in this
matter. Although 0.1 wavelength is more than enough to cover a urban
lot and your neighbor at short wave frequencies theory does not do
justice to a non homogenous environment we all live in. Most electronic
noise generators do not have efficient antennas attached to them where
the environment easily distorts the electric fields. I have repeatedly
experienced predominantly voltage common mode coupling of local noise
sources. Without exception mitigation methods against voltage common
mode noise were always successful and current mode antennas always
picked up less local noise.

They don't but if you go by the advice you generally get on the antenna
group, you run an unshielded lead in (part of the antenna) right into the
shack (big noise source). When I made my prior comments about the lack of
consideration given to receive antenna, I was referring to the antenna
group. I didn't realize that the message was cross posted. It just amazes me
that they will debate a transmitting antenna to minute detail but receiving
antennas deserve no consideration other than a random piece of wire thrown
into a tree. Despite their often one sidedness I have learned a great deal
from them and mean no disrespect.


" Uncle Peter" wrote in message
news:sBEDc.1168$Rr2.4@lakeread03...

How does the antenna differentiate between "noise" and a valid signal?