Dear friends

It is usually said (in my country) that the double bazooka antenna is
less noisy than a standard dipole.
I think that there are not good reasons that endorse such a statement
for noises coming from the far field (maybe it has some advantage with
near field noises or maybe because its frequency response cures some
pitfails of the associated receiver).

I have looked for information in the net about this topica but I have
not been lucky.

I suppose that you have treated this topic at some time. If you can
point me to a link to read about I would be very grateful to you.

Also if you can give me your opinion in this respect.

Thank you very much in advance

Miguel (LU 6ETJ)

lu6etj wrote:
I have looked for information in the net about this topica but I have
not been lucky.

Try http://www.w2du.com/r2ch18.pdf Being lossy reduces the
noise but not the signal to noise ratio.
--
73, Cecil http://www.qsl.net/w5dxp

lu6etj wrote:
Dear friends

It is usually said (in my country) that the double bazooka antenna is
less noisy than a standard dipole.
I think that there are not good reasons that endorse such a statement
for noises coming from the far field (maybe it has some advantage with
near field noises or maybe because its frequency response cures some
pitfails of the associated receiver).

I tested an IAC double bazooka, and it is no different than a regular
dipole. It has very slightly less signal level, and very slightly more
bandwidth. Not enough to worry about. No measurable difference in
noise.

73 Tom

wrote in message
oups.com...

lu6etj wrote:
Dear friends

It is usually said (in my country) that the double bazooka antenna is
less noisy than a standard dipole.
I think that there are not good reasons that endorse such a statement
for noises coming from the far field (maybe it has some advantage with
near field noises or maybe because its frequency response cures some
pitfails of the associated receiver).

I tested an IAC double bazooka, and it is no different than a regular
dipole. It has very slightly less signal level, and very slightly more
bandwidth. Not enough to worry about. No measurable difference in
noise.

73 Tom


We beat bazookas to death here years ago.
Don't waste your time.

73
H.
NQ5H

Dear friends:

Thank you very much for your answers.

First of all: I agree with you, but my agreement is inductive, not
experimental because I have not made my homework with that antenna...
..
I knew the excellent article of Walter Maxwell, I am a fan of Maxwell,
(both Maxwells) from their famous article "Another look on reflections"

But do I think: is it possible that all those friends that are
enthusiastic of the bazooka are affirming foolishness? They say: -With
the bazooka we listen stations that we don't with the plain dipole, and
this affirmatiotn point to a better SNR...

I think that it must have something true behind so many similar
statements. In the radio club of my area they say to have compared one
against another with clearly favorable results to the bazooka.

I thought...: A plain dipole is not a monoband antenna, it is, in fact,
a multiband antenna, it receives all the frequencies. But do let us
imagine a plain dipole that had connected on its terminals a couple
high Q tuned circuits. That system it would be really "monoband"...
then, if we connect such a system to a poor receiver Would not it
improve the reception perhaps?, eliminating by that way possible
saturation sources or intermodulación noises.
Such a system, empirically it would seem a practically "more silent
antenna" and it would explain, perhaps, the some results obtained by
the colleagues. I say this because it is said that the bazooka
possesses a syntony effect that transforms it into a true monoband
device (I am not sure of it).

It is only an arbitrary example of possible alternative explanations
that, without violating the fundamental principles, can be
compatibilized with the experiences of so many colleagues that
sympathize with this antennas(some of which deserve my technical
respect).

I thank all your answers but I continue to the search of some
explanation that endorses all the facts, just as the formidable article
of Walter in reference to its bandwidth...

I am for sure some of you will be able to help me to find a convincing
explanation.

Thank you very much in adavnce

Miguel Ghezzi (LU 6ETJ)

Miguel
There are "eyewitness accounts" of all sorts of foolishness.

If you build it perfectly a bazooka will show a decrease in SWR over a very
small range either side of resonance (SWR = 1:1) when compared to a dipole.
This is completely useless except as an academic exercise.

Here's how it works:
The antenna is a parallel-resonant network (the bazooka) in parallel with a
series-resonant network(the dipole).
The parallel resonant (tank circuit) network stores energy and will
oscillate at it's DRIVEN frequency when driven near resonance, so it stores
the energy that would otherwise be reflected as long as it oscillates. Go
too far from resonance and it quits oscillating. This effect manifests
itself at SWR of 1.2:1 or lower. It flattens the SWR curve very near
resonance.
The 2:1 bandwidth is unaffected except by the additional loss of the tank
circuit sitting across the dipole feed point.

What Walter Maxwell showed explicitly is that any increase in SWR bandwidth
is entirely due to loss, if I recall correctly.

So all the trouble of building a bazooka with both legs and the dipole
resonant at exactly the same frequency is a waste of time.
A simple dipole works a bit better and is *MUCH LESS* work and expen$e.

73
H.
NQ5H


"lu6etj" wrote in message
oups.com...

Dear friends:

Thank you very much for your answers.

First of all: I agree with you, but my agreement is inductive, not
experimental because I have not made my homework with that antenna...
..
I knew the excellent article of Walter Maxwell, I am a fan of Maxwell,
(both Maxwells) from their famous article "Another look on reflections"

But do I think: is it possible that all those friends that are
enthusiastic of the bazooka are affirming foolishness? They say: -With
the bazooka we listen stations that we don't with the plain dipole, and
this affirmatiotn point to a better SNR...

I think that it must have something true behind so many similar
statements. In the radio club of my area they say to have compared one
against another with clearly favorable results to the bazooka.

I thought...: A plain dipole is not a monoband antenna, it is, in fact,
a multiband antenna, it receives all the frequencies. But do let us
imagine a plain dipole that had connected on its terminals a couple
high Q tuned circuits. That system it would be really "monoband"...
then, if we connect such a system to a poor receiver Would not it
improve the reception perhaps?, eliminating by that way possible
saturation sources or intermodulación noises.
Such a system, empirically it would seem a practically "more silent
antenna" and it would explain, perhaps, the some results obtained by
the colleagues. I say this because it is said that the bazooka
possesses a syntony effect that transforms it into a true monoband
device (I am not sure of it).

It is only an arbitrary example of possible alternative explanations
that, without violating the fundamental principles, can be
compatibilized with the experiences of so many colleagues that
sympathize with this antennas(some of which deserve my technical
respect).

I thank all your answers but I continue to the search of some
explanation that endorses all the facts, just as the formidable article
of Walter in reference to its bandwidth...

I am for sure some of you will be able to help me to find a convincing
explanation.

Thank you very much in adavnce

Miguel Ghezzi (LU 6ETJ)

lu6etj wrote:
But do I think: is it possible that all those friends that are
enthusiastic of the bazooka are affirming foolishness? They say: -With
the bazooka we listen stations that we don't with the plain dipole, and
this affirmatiotn point to a better SNR...

The Double Bazooka is probably quieter than a plain dipole
because, unlike a plain dipole, there is a DC path between
all points in the antenna thus minimizing the effects of
precipitation static.
--
73, Cecil http://www.qsl.net/w5dxp

"Cecil Moore" wrote in message
y.net...
lu6etj wrote:
But do I think: is it possible that all those friends that are
enthusiastic of the bazooka are affirming foolishness? They say: -With
the bazooka we listen stations that we don't with the plain dipole, and
this affirmatiotn point to a better SNR...

The Double Bazooka is probably quieter than a plain dipole
because, unlike a plain dipole, there is a DC path between
all points in the antenna thus minimizing the effects of
precipitation static.
--
73, Cecil http://www.qsl.net/w5dxp

So a nice 2.5 K ohm resistor at the feed point of a dipole would be vastly
less work.




"With
the bazooka we listen stations that we don't with the plain dipole"

I doubt anyone can document that.

H. Adam Stevens, NQ5H wrote:
"Cecil Moore" wrote in message
The Double Bazooka is probably quieter than a plain dipole
because, unlike a plain dipole, there is a DC path between
all points in the antenna thus minimizing the effects of
precipitation static.

So a nice 2.5 K ohm resistor at the feed point of a dipole would be vastly
less work.

Yes, it has nothing to do with SWR or bandwidth. I reduced
the precipitation static problem in the Arizona desert by
going to a full wave 40m loop, the one on my web page.
--
73, Cecil http://www.qsl.net/w5dxp

lu6etj wrote:
I think if this was the case would be enough to install on plain dipole
a RF ckoke or standard trifilar balun + a ckoke to ground on de rig.
what do you think about?

I would like to see the noise comparisons among a Double
Bazooka, a plain dipole, and a folded dipole. My Arizona
desert precipitation problem certainly decreased when
I went from a G5RV to a full-wave 40m loop.

With the G5RV, one element was grounded through the coax
shield and the other element was capacitor isolated from
ground by a series cap in my transceiver. It arced at the
coax connector and a choke did solve the arcing problem.
--
73, Cecil http://www.qsl.net/w5dxp