On Sun, 27 Jun 2004 19:55:58 -0700, "CW" no adddress@spam free.com
wrote:

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.

Hi OM,

As generalizations go, this one falls short with them all.

We here at rec.radio.amateur.antenna often recite the credo that
"reciprocity rules." This means that all considerations given to a
transmitting antenna are equally applied to receiving antennas.

However, I am sure you are responding to the disparity in coverage
between receiving and transmitting antennas - and this is for good
reason. Reception and Transmission are NOT reciprocal operations. A
receiver has far more latitude to accomplish its goal than does a
transmitter. Unless you have an abysmal receiver poorly connected to
an inadequate whip, the stock receiver with a simple length of wire is
often very close to doing a good job. If the receiver suffers from
any of a multitude of issues, there is generally a solution that
answers the problem specifically. About the only thing you can do for
the transmitter is to turn up the power, or lower the transmission
loss. It stands to reason that our focus is on optimizing the loss
side of the balance ledger.

Returning to the credo of "reciprocity rules," any gain to the
advantage of a transmitter is enjoyed by the receiver and the SWLer
stands the same advantage. But if that advantage is measured at 3dB,
this has the significance of 50W in 100W compared to the SWL S-Meter
change from S5 to S6 (BFD). Even though it is the same 3dB, there is
the illusion of perspective (my 50W compared to your 5µV). If the SW
station is buried in S9 noise, then this is not an antenna problem
(unless you can null the noise out through careful lobe positioning).
Filtering and/or DSP stand to answer the problem, but these are
obviously not remedies to transmission issues.

There is another thread discussing the goal of constructing a small
loop for 80M reception (and how well 5 turns might achieve some
benefit). The same issues of loss prevail for the comparison of
Radiation Resistance to Ohmic Resistance for a 1 Meter loop. The loop
Rr is in the thousandths of an Ohm and about on par for a small wire's
Ohmic loss. There's that 3dB again and what concerns the transmission
efficiency is far easier to tolerate with the receiver and its surplus
of gain. If the SWLer pays attention to this issue as it concerns the
transmission problems, then that SWLer stands to gain in the
efficiency returned. However, this is not to suggest that there is an
actual need to obtain this efficiency; but if the SWLer mismanages the
construction, the topic is discussed to the necessary depth to correct
it.

A simple basis of comparison will illustrate. Many SW radios have a
ferrite stick antenna that will work with at least some stations (VOA,
WWV, BBC and a host of others). Try transmitting through that same
ferrite stick and it will be like trying to shout through a straw.
Our only alternative is to add an amp, but the big KW is only going to
render smoke.

73's
Richard Clark, KB7QHC

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 ,
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

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.

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.

"CW" no adddress@spam free.com wrote in message ...
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.



CW,

That is 'why' I set-up the "Shortwave Listeners (SWL) AM/FM Antennas"
eGroup on YAHOO !
SWL-ANT= http://groups.yahoo.com/group/Shortwave-SWL-Antenna/

Most HAM are concerned about getting the most power transfer
into the Antenna and the greatest Signal Output from the
Antenna. This may not result in the best receiving antenna.
A better SWL Receive ONLY Antenna is usually a result of
a Clean 'outside' Signal with a "Low Noise" factor.

Yes the topic is SWL Receive ONLY Antennas.
SWL-ANT= http://groups.yahoo.com/group/Shortwave-SWL-Antenna/

iane ~ RHF

..

"CW" no adddress@spam free.com wrote in message ...
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.



CW,

That is 'why' I set-up the "Shortwave Listeners (SWL) AM/FM Antennas"
eGroup on YAHOO !
SWL-ANT= http://groups.yahoo.com/group/Shortwave-SWL-Antenna/

Most HAM are concerned about getting the most power transfer
into the Antenna and the greatest Signal Output from the
Antenna. This may not result in the best receiving antenna.
A better SWL Receive ONLY Antenna is usually a result of
a Clean 'outside' Signal with a "Low Noise" factor.

Yes the topic is SWL Receive ONLY Antennas.
SWL-ANT= http://groups.yahoo.com/group/Shortwave-SWL-Antenna/

iane ~ RHF

..

= = = Richard Clark wrote in message
= = = . ..
On Sun, 27 Jun 2004 19:55:58 -0700, "CW" no adddress@spam free.com
wrote:

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.

Hi OM,

As generalizations go, this one falls short with them all.

We here at rec.radio.amateur.antenna often recite the credo that
"reciprocity rules." This means that all considerations given to a
transmitting antenna are equally applied to receiving antennas.

However, I am sure you are responding to the disparity in coverage
between receiving and transmitting antennas - and this is for good
reason. Reception and Transmission are NOT reciprocal operations. A
receiver has far more latitude to accomplish its goal than does a
transmitter. Unless you have an abysmal receiver poorly connected to
an inadequate whip, the stock receiver with a simple length of wire is
often very close to doing a good job. If the receiver suffers from
any of a multitude of issues, there is generally a solution that
answers the problem specifically. About the only thing you can do for
the transmitter is to turn up the power, or lower the transmission
loss. It stands to reason that our focus is on optimizing the loss
side of the balance ledger.

Returning to the credo of "reciprocity rules," any gain to the
advantage of a transmitter is enjoyed by the receiver and the SWLer
stands the same advantage. But if that advantage is measured at 3dB,
this has the significance of 50W in 100W compared to the SWL S-Meter
change from S5 to S6 (BFD). Even though it is the same 3dB, there is
the illusion of perspective (my 50W compared to your 5µV). If the SW
station is buried in S9 noise, then this is not an antenna problem
(unless you can null the noise out through careful lobe positioning).
Filtering and/or DSP stand to answer the problem, but these are
obviously not remedies to transmission issues.

There is another thread discussing the goal of constructing a small
loop for 80M reception (and how well 5 turns might achieve some
benefit). The same issues of loss prevail for the comparison of
Radiation Resistance to Ohmic Resistance for a 1 Meter loop. The loop
Rr is in the thousandths of an Ohm and about on par for a small wire's
Ohmic loss. There's that 3dB again and what concerns the transmission
efficiency is far easier to tolerate with the receiver and its surplus
of gain. If the SWLer pays attention to this issue as it concerns the
transmission problems, then that SWLer stands to gain in the
efficiency returned. However, this is not to suggest that there is an
actual need to obtain this efficiency; but if the SWLer mismanages the
construction, the topic is discussed to the necessary depth to correct
it.

A simple basis of comparison will illustrate. Many SW radios have a
ferrite stick antenna that will work with at least some stations (VOA,
WWV, BBC and a host of others). Try transmitting through that same
ferrite stick and it will be like trying to shout through a straw.
Our only alternative is to add an amp, but the big KW is only going to
render smoke.

73's
Richard Clark, KB7QHC

RC,

In the same location using the same Antenna:

100uV of background noise being re-radiated by a Transmitting
Antenna that is being powered at 50W or 100W is simply not an
issue for the Amateur/HAM.
- Background Noise is NOT an Issue when thinking of Transmitting
Antennas that are Radiating Power in the Tens and Hundreds of Watts.
- For the HAM Signal-to-Noise is NOT a Transmission Antenna Parameter.

100uV of background noise being received by a Receiving Antenna
that is seeking a 25uV Signal is unacceptable for a SWLer.
- Background Noise IS an Issue when thinking of Receiving Antennas
that are 'acquiring' Radiated Power in the Milliwatts or micro-watts.
- For the SWLer Signal-to-Noise IS a key Receiving Antenna Parameter.

iane ~ RHF
..
Shortwave Listeners (SWL) AM/FM Antennas eGroup on YAHOO !
SWL-ANTENNA= http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
..