On Fri, 21 Sep 2007 14:28:47 GMT, Navtex-Fan wrote:

Hi group,

I'm a SWL and am specially interested in Navtex DX-reception.My problem
is (was) the heavy QRM from about every TV-set, monitor, PC in the
neighbourhood.

I'm currently using a T-aerial: horizontal wire 20 meters long, ca. 10
meter above ground, vertical part ca. 10 meter down from the middle, =
1:9 "magnetic" balun = 25 meter RG58 to receiver. Receiver is located
on the first floor, and is grounded via a thick wire to the earth pin
of the house. Typical reception sounds like this:

http://users.pandora.be/dirk.claessens2/div/not_grounded.wav

...humming, hissing, hard to decode, nightmare.

In despair - and against all advise in antenna textbooks (ground
loops!) -

I have never seen "ground loops" mentioned in an antenna book.
Ground loops are a main problem in audio frequency equipment,
not in HF.

In high frequency equipment GROUND EVERY POINT YOU CAN
to create a quasi-reference potential area as large as possible.

The usual way to overcome stray noise from nearby sources
a

1.) Electrostatic shielding of the antenna.
Use coax for the horizontal dipoles, and ground the coax shield
at the ends but do not create short circuited loops.
(do not confuse with "ground loops")
2. Use a noise eliminator which feeds a phase shifted signal
from a small local antenna into a combining network.
3. Improve grounding as you did.

To me it is not quite clear what happened in your case,
but antennas are and have always been much try-and-error.
w.

I decided to make an additional earth point at the balun. I
drove two 1 meter 1/2 inch copperpipes into the ground, and connected
these to the shield of the RG58 at the balun. Grounding at the receiver
was unchanged. The result was stunning:

http://users.pandora.be/dirk.claessens2/div/grounded.wav

QRM totally gone!
Can anyone explain this?

Thanks for any insight - Dirk

On 21 Sep, 12:14, Helmut Wabnig .... .-- .- -... -. .. --.
@ .- --- -. dot .- - wrote:
On Fri, 21 Sep 2007 14:28:47 GMT, Navtex-Fan wrote:
Hi group,

I'm a SWL and am specially interested in Navtex DX-reception.My problem
is (was) the heavy QRM from about every TV-set, monitor, PC in the
neighbourhood.

I'm currently using a T-aerial: horizontal wire 20 meters long, ca. 10
meter above ground, vertical part ca. 10 meter down from the middle, =
1:9 "magnetic" balun = 25 meter RG58 to receiver. Receiver is located
on the first floor, and is grounded via a thick wire to the earth pin
of the house. Typical reception sounds like this:

http://users.pandora.be/dirk.claessens2/div/not_grounded.wav

...humming, hissing, hard to decode, nightmare.

In despair - and against all advise in antenna textbooks (ground
loops!) -

I have never seen "ground loops" mentioned in an antenna book.
Ground loops are a main problem in audio frequency equipment,
not in HF.

In high frequency equipment GROUND EVERY POINT YOU CAN
to create a quasi-reference potential area as large as possible.

The usual way to overcome stray noise from nearby sources
a

1.) Electrostatic shielding of the antenna.
Use coax for the horizontal dipoles, and ground the coax shield
at the ends but do not create short circuited loops.
(do not confuse with "ground loops")
2. Use a noise eliminator which feeds a phase shifted signal
from a small local antenna into a combining network.
3. Improve grounding as you did.

To me it is not quite clear what happened in your case,
but antennas are and have always been much try-and-error.
w.



I decided to make an additional earth point at the balun. I
drove two 1 meter 1/2 inch copperpipes into the ground, and connected
these to the shield of the RG58 at the balun. Grounding at the receiver
was unchanged. The result was stunning:

http://users.pandora.be/dirk.claessens2/div/grounded.wav

QRM totally gone!
Can anyone explain this?

Thanks for any insight - Dirk- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

Hi, let me clarify your problem. The most efficient radiator is one
wave length long where it is considered to be in equilibrium with a
parallel electrical cuircuit
instead of the usual series circuit. For most efficient radiation both
the capacitance and the inductance
must act as a energy storage such that when the terminals are shorted
the energy is released in a burst such that radiation can begin,
the electrical circuit by the way is often called a TANK cuircuit. In
the case of a fractional wave length radiator the pendulum type
radiation is not available for radiation and thus it travels up the
outside of the coax where it can radiate or become part of the "real
resistance" of the radiator in a similar way a vertical 1/2 wave
antenna would do when half of the applied energy is absorbed by the
ground.
Per the replies you will see what these currents are named when one
has an antenna that wants to work as a full wave length long even tho
a 1/2 wave length of the radiator is missing for max efficiency.
Hope that helps
Regards
Art KB9MZ

On 2007-09-22, art (74.133.197.189) wrote in
message .com

In the case of a fractional wave length radiator the pendulum type
radiation is not available for radiation and thus it travels up the
outside of the coax where it can radiate or become part of the "real
resistance" of the radiator in a similar way a vertical 1/2 wave
antenna would do when half of the applied energy is absorbed by the
ground.

Sure, Navtex is broadcasted on 518/490 KHz. Even a 1/4 wavelength
antenna is beyond my real estate capabilities. :-(


Per the replies you will see what these currents are named when one
has an antenna that wants to work as a full wave length long even tho
a 1/2 wave length of the radiator is missing for max efficiency.
Hope that helps
Regards
Art KB9MZ

Thanks for the info Art, it is appreciated.

73 - Dirk

--
Dirk.
No trees were killed in the creation of this message;
however, many electrons were terribly inconvenienced.
http://users.pandora.be/dirk.claessens2

"art" wrote
The most efficient radiator is one wave length long where
it is considered to be in equilibrium with a parallel electrical
cuircuit.

For most efficient radiation both the capacitance and the
inductance must act as a energy storage such that when
the terminals are shorted the energy is released in a burst
such that radiation can begin. ... In the case of a fractional
wave length radiator the pendulum type radiation is not
available for radiation
___________

Note (for one example of many) that in an antenna system consisting of a
1/2-wave, center-fed dipole driven by a matched, balanced transmission line,
the dipole itself radiates virtually all of the r-f energy present at the
antenna feedpoint.

The radiation efficiency of a system as in the above example, but using a
full wave dipole is no better than the 1/2-wave version, other things equal.
The full wave version just has a different radiation pattern.

RF

On 22 Sep, 07:22, "Richard Fry" wrote:
"art" wrote

The most efficient radiator is one wave length long where
it is considered to be in equilibrium with a parallel electrical
cuircuit.
For most efficient radiation both the capacitance and the
inductance must act as a energy storage such that when
the terminals are shorted the energy is released in a burst
such that radiation can begin. ... In the case of a fractional
wave length radiator the pendulum type radiation is not
available for radiation

___________

Note (for one example of many) that in an antenna system consisting of a
1/2-wave, center-fed dipole driven by a matched, balanced transmission line,
the dipole itself radiates virtually all of the r-f energy present at the
antenna feedpoint.

The radiation efficiency of a system as in the above example, but using a
full wave dipole is no better than the 1/2-wave version, other things equal.
The full wave version just has a different radiation pattern.

RF

On 22 Sep, 07:22, "Richard Fry" wrote:
"art" wrote

The most efficient radiator is one wave length long where
it is considered to be in equilibrium with a parallel electrical
cuircuit.
For most efficient radiation both the capacitance and the
inductance must act as a energy storage such that when
the terminals are shorted the energy is released in a burst
such that radiation can begin. ... In the case of a fractional
wave length radiator the pendulum type radiation is not
available for radiation

___________

Note (for one example of many) that in an antenna system consisting of a
1/2-wave, center-fed dipole driven by a matched, balanced transmission line,
the dipole itself radiates virtually all of the r-f energy present at the
antenna feedpoint.

The radiation efficiency of a system as in the above example, but using a
full wave dipole is no better than the 1/2-wave version, other things equal.
The full wave version just has a different radiation pattern.

RF

I don't know what your credentials are for you to make such a
statement but it is a free world after all!
A quad radiator is a wave length radiator with a gain more than a half
wave as one sample.
Computor programing confirmes more radiation from full wave antennas
and mathematics according to Maxwell,s rules substantiate it. I can
understand not believing computor programs but I am very interested in
any mathematical data that would support your stand which is contrary
to the mathematics that I and others support.
What you are stating is that an attena in a series cuircit format
produces the same radiation as a parallel or tank cuircuit. I am more
than eager to read the contrary mathematical proof that is contrary to
the mathematics that I hold true. You may have hit on the true
explaqnation of radiation which Einstein, Planck and many others went
to their grave without solving it
Regards
Art KB9MZ.....XG

"art" wrote
A quad radiator is a wave length radiator with a gain more
than a half wave as one sample.

In your first post you wrote, "The most efficient radiator is one wave
length long where it is considered to be in equilibrium with a parallel
electrical cuircuit," and that is what I responded to.

Now you are writing about gain. Efficiency and gain are not synonymous.

Both of the dipole antennas in my previous post will radiate nearly 100% of
the r-f energy available from a matched, balanced source connected to their
input terminals. Therefore the radiation efficiency of those two
configurations does not favor the 1-wave over the 1/2-wave, which was your
opening premise.

They won't have the same gains in every direction, because their radiation
patterns are different. Same for your quad and "half wave" example.

RF

On 22 Sep, 12:33, "Richard Fry" wrote:
"art" wrote

A quad radiator is a wave length radiator with a gain more
than a half wave as one sample.

In your first post you wrote, "The most efficient radiator is one wave
length long where it is considered to be in equilibrium with a parallel
electrical cuircuit," and that is what I responded to.

Now you are writing about gain. Efficiency and gain are not synonymous.

Both of the dipole antennas in my previous post will radiate nearly 100% of
the r-f energy available from a matched, balanced source connected to their
input terminals. Therefore the radiation efficiency of those two
configurations does not favor the 1-wave over the 1/2-wave, which was your
opening premise.

They won't have the same gains in every direction, because their radiation
patterns are different. Same for your quad and "half wave" example.

RF

O.K. I may have muddied things. I hold to the fact that a one
wavelength dipole will always radiate at a higher efficiency than a
1/2 wave dipole. The example I gave as for an instance was a quad
versus a 1/2 wave dipole.
This is readily seen by any operator empirically. Mathematically it is
proven that way also even tho both are in accordance to Maxwell's
laws. You could I suppose compare a series antenna with a parallel
circuit i.e. a tank circuit that could reinforce your point and that
is what I hoped you would come up with to bolster your point without
resorting to a computor program based on Maxwellian laws. There is
much discussion about what creates radiation and I thought you may
have come up with something that we can all learn from. Eventually
even tho the past masters have died some one, possibly you, will
discover that which has eluded all, even quallified scientists with
huge resumes. I am willing to give you a hearing which does not often
happen on this newsgroupAs an aside I suspect that a single quad
element will beat a dipole anyway regardles of what the fields
differences that you point to but again I am very interested in any
mathematics that defends your possition possibly starting witha
parallel versus a series arrangement since it is very clear whatstarts
radiation in the parallelcase but unknown mathematically for the
series circuit.
Very best regards
Art Unwin....KB9MZ

On 22 Sep, 15:40, art wrote:
On 22 Sep, 12:33, "Richard Fry" wrote:





"art" wrote

A quad radiator is a wave length radiator with a gain more
than a half wave as one sample.

In your first post you wrote, "The most efficient radiator is one wave
length long where it is considered to be in equilibrium with a parallel
electrical cuircuit," and that is what I responded to.

Now you are writing about gain. Efficiency and gain are not synonymous.

Both of the dipole antennas in my previous post will radiate nearly 100% of
the r-f energy available from a matched, balanced source connected to their
input terminals. Therefore the radiation efficiency of those two
configurations does not favor the 1-wave over the 1/2-wave, which was your
opening premise.

They won't have the same gains in every direction, because their radiation
patterns are different. Same for your quad and "half wave" example.

RF

O.K. I may have muddied things. I hold to the fact that a one
wavelength dipole will always radiate at a higher efficiency than a
1/2 wave dipole. The example I gave as for an instance was a quad
versus a 1/2 wave dipole.
This is readily seen by any operator empirically. Mathematically it is
proven that way also even tho both are in accordance to Maxwell's
laws. You could I suppose compare a series antenna with a parallel
circuit i.e. a tank circuit that could reinforce your point and that
is what I hoped you would come up with to bolster your point without
resorting to a computor program based on Maxwellian laws. There is
much discussion about what creates radiation and I thought you may
have come up with something that we can all learn from. Eventually
even tho the past masters have died some one, possibly you, will
discover that which has eluded all, even quallified scientists with
huge resumes. I am willing to give you a hearing which does not often
happen on this newsgroupAs an aside I suspect that a single quad
element will beat a dipole anyway regardles of what the fields
differences that you point to but again I am very interested in any
mathematics that defends your possition possibly starting witha
parallel versus a series arrangement since it is very clear whatstarts
radiation in the parallelcase but unknown mathematically for the
series circuit.
Very best regards
Art Unwin....KB9MZ- Hide quoted text -

- Show quoted text -

Wait a minuit! you stated that a half wave antenna was nearly 100%
efficient and therein may be the true answer
A quad is often considered as two dipoles even tho there is only one
feed point thus efficiency per unit!Then one can refer to efficiency
per unit length. Is that your point?
Art

"art" wrote
O.K. I may have muddied things. I hold to the fact that a one
wavelength dipole will always radiate at a higher efficiency than a
1/2 wave dipole.
_________

Please post your definition of "efficiency," in this context.

RF