On Thu, 04 Mar 2004 22:31:40 GMT, "aunwin"
wrote:
....
give the pros and cons between a series
circuit and a parallel circuit from which to base a radiator ?
....
Just to give you a start a series circuit radiator is a dipole.

And we will
say a parallel circuit radiator is one with at least one capacitive lumped
circuit and one inductive lumped circuit in parallel.
....
Here is a start
A dipole provides a lot of signals at the same time( good)
A parallel circuit can only supply one signal at a time (bad )
Get the idea?

Hi Art,

A dipole is the most efficient antenna.

The parallel circuit offers loss to an already most efficient antenna.

A dipole is simple to load and often requires no matching.

The parallel circuit is difficult to load and always requires
matching.

A dipole offers a standard of gain.

The parallel circuit offers no change in gain except the prospect of
reducing it through making the antenna smaller to become a resonant
system.

A dipole is a simple construction.

The parallel circuit adds complexity which raises the prospects of
mechanical and electrical failure.

A dipole offers hazardous potentials at its tips.

A parallel circuit double that danger by offering hazardous potentials
at both its tips and its drive point.

A dipole requires isolation/insulation at its tips due to high
potentials.

A parallel circuit requires isolation/insulation at its drive point
AND its tips due to high potentials.

Is that the idea? I presume you can distinguish good/bad.

73's
Richard Clark, KB7QHC

Thank you ,thank you Richard.
I now have something to think about as to why I have been so
misdirected these past few years where everybody knew I was wrong and I have
yet to reason why. That is why I hoped only experts would respond after
seeing the response to Reg on another thread. Get back to you later if I see
the serious difference of thought that exists between myself and others
regarding where and why I am out in 'left field' (Baseball talk Reg).
Hopefully some other experts will contribute with statements that are
specific, to the point and beyond question that may bring to light some
bogies that are messing me up.
Best regards
Art


"Richard Clark" wrote in message
...
On Thu, 04 Mar 2004 22:31:40 GMT, "aunwin"
wrote:
...
give the pros and cons between a series
circuit and a parallel circuit from which to base a radiator ?
...
Just to give you a start a series circuit radiator is a dipole.

And we will
say a parallel circuit radiator is one with at least one capacitive
lumped
circuit and one inductive lumped circuit in parallel.
...
Here is a start
A dipole provides a lot of signals at the same time( good)
A parallel circuit can only supply one signal at a time (bad )
Get the idea?

Hi Art,

A dipole is the most efficient antenna.

The parallel circuit offers loss to an already most efficient antenna.

A dipole is simple to load and often requires no matching.

The parallel circuit is difficult to load and always requires
matching.

A dipole offers a standard of gain.

The parallel circuit offers no change in gain except the prospect of
reducing it through making the antenna smaller to become a resonant
system.

A dipole is a simple construction.

The parallel circuit adds complexity which raises the prospects of
mechanical and electrical failure.

A dipole offers hazardous potentials at its tips.

A parallel circuit double that danger by offering hazardous potentials
at both its tips and its drive point.

A dipole requires isolation/insulation at its tips due to high
potentials.

A parallel circuit requires isolation/insulation at its drive point
AND its tips due to high potentials.

Is that the idea? I presume you can distinguish good/bad.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Thu, 04 Mar 2004 21:36:22 GMT, "aunwin"
wrote:
What is it about parallel circuits that make them unsuitable?

They are used every day to load up halfwave verticals, which in turn
are also parallel equivalent circuits.

Did you mean that? A halfwave vertical is a parallel circuit!

That is the longstanding convention. Same thing applies to a one
wavelength dipole. All such are the basis of the J-Pole and the Zepp
(when you strip away their matching sections).

Well that is new to me, I never consider the matching circuit as part of an
antenna but only a required band aid. Can you point me
to where this is discussed ? ( J pole I know nothing about but the others I
would like to read of what you refer to as a parallel circuit) This could
be the point of confusion.





The input to the parallel
interface is performed through divider action (usually a tapped coil,
but could be through a capacitor divider).

Yes I know that but the question did say antennas didn't it?

Antennas don't find much application without some method of driving
them. Very few successful halfwave designs exist without matching.
This is because the halfwave vertical, looking like a parallel
circuit, has a considerable amount of Z that rejects power (unless
your rig is a van-de-graff generator). Adding the radiation
resistance to a high Z hardly allows any current into the radiation
resistance. On the other hand, a quarterwave looks like a series
resonant circuit with very low Z, and thus the radiation resistance
absorbs all the power applied. Very simple electronics.

One solution to feeding the halfwave tall vertical is to break it in
half and feed it half way up (where the two sections look like series
resonant, low Z elements feeding the radiation resistance without much
impediment). This is simplified, of course, but it illustrates how
the same circuit can support either a series resonant or parallel
resonant description determined only by the topology of connection.

You gave an answer to a question that was not asked. What you are
refering
to is not for its radiation attributes is it? I hope we are not going
into a
multi heading thread mode in less than 12 hours.

Matching sections to the J-Pole and the Zepp are contributors to
radiation due to the unbalanced nature of those antennas designs. How
much they contribute is perhaps arguable, but when they are built in
without care, their contribution cannot be denied. The matching
circuits contain both circulating currents and common mode currents.
The common mode currents, as a function of the physical length
compared to wavelength, offer radiation. The radiation may aid, or it
may hinder, but it is there none the less.

Is stagger tuning a parallel circuit ?

No, but it could be. Stagger tuning, by convention is a chain of
separately tuned circuits, be they RC, RL, or LC (or, of course RLC).

You mentioned the all important word of "tuned" so all of the above are
parallel circuits....right?

No, but they could be. The application of drive and loads determine
the topology:

One RC or RL circuit exhibits a 6dB/Octave or 10dB/Decade roll-off.
One LC circuit exhibits twice that or a 12dB/Octave or 20dB/Decade
roll-off. Again, it is all a matter of connections for the identical
components (which will show a slight shift in parallel to series
resonance frequency - which is to say it is application
dependent).

I totally miss this point and probably the blame is mine. I think you are
saying that yes, they are parallel circuits, but you have an exception
that
you want to point out i.e.slight shift in parallel to series...........

No, they are NOT parallel - they could be, but there is nothing
inherently parallel and it all depends on the drive and load applied.

Not sure if you are saying 'yes'. I personaly think it is a parallel
circuit to which I would answer 'yes'.

No, they are NOT parallel - they could be, but there is nothing
inherently parallel and it all depends on the drive and load applied.

Well on that note I see a dipole as a single series circuit fed by a
generator( ARRL book), where-as I see a bandpass circuit as a parallel
circuit.
This can be made to LOOK like several series circuits IF and Only IF one
discardes the intercoupling factor, and I do not see how one can
realistically refer to such an arrangement in any way as a quasi or
something else with the term 'series'
..

Force
12 has stagger tuning, if it is series devised then it gives more ammo to
the 'do not use parallel circuits for antennas' argument which seems to
be
prevalent with antenna experts.

Force 12 makes many antennas, I will presume you are speaking of some
beam array. Stagger tuning, in that sense, is much akin to the
reflector, radiator, director relationship of the yagi. That design
is stagger tuned, but such stagger tuning is to accomplish various
delays that aid gain in one direction, and negate it in another. Such
stagger tuning is not directly engaged upon for the purpose of
bandwidth, although it may have indirect consequences.


Oh I will have to leave that for others to comment upon as that is not what
I consider stagger tuning to be. I mentioned in another posting what I
thought it to be, so obviously there are comments on the way to put me
straight, hopefully in a factual way that puts the majority at ease. without
a complication factor.


I have a beam
array for 440 that employs an LPDA radiator tied into the conventional
reflector and directors. As such it performs stagger tuning for the
purpose of beam forming AND bandwidth.

The elements in the Fan Dipole or the Log Periodic Dipole Array more
closely align to the conventional meaning of stagger tuning. The Fan
Dipole is the most obvious case. It's metaphor would be as many
parallel, series resonant circuits as there are elements, each
slightly tuned off from the other, all feeding in series and combining
in parallel to average a wider bandwidth response than any single
series resonant element.

I just don't understand what you are saying here, I must understand the
parallel circuit part of a zepp or dipole part first to intellegently
discuss all this other stuff you are talking about.
The statements you are making on parallel versus series I view as enormous.
Read the ARRL book on antennas and they dwell on series circuits as in
dipole, why the big difference with this newsgroup? Your comments seem to
rotate about phase changes more than it does about coupling as to the main
focal point.
No comments on your other posting yet .(pro and con) which suggest the
experts are unified on your statements.
I will have to choose my words very, very carefully tomorrow on that one.Up
to now I feel fully exposed on what I don't know that which every body else
knows
73's
Regards
Art
Richard Clark, KB7QHC

aunwin wrote:

Why must only series circuits be considered for radiators?.

Just thinking out loud. I'm not sure I'm correct but the following seems
to make a little sense.

In a series resonant circuit the net reactance is zero. As the frequency
is changed slightly from resonance the reactance increases slowly from
zero. This is algebraic addition of plus and minus terms.

In a parallel circuit the net reactance is the product of the two terms
divided by the sum [and has a high net value]. As the frequency is
changed slightly from resonance the net reactance does not change from
'zero' it changes from a high value to a lower value.

My conclusion is that a series circuit more closely matches actual
antenna performance as the antenna impedance varies from resonance.

DD

SNIPPED

Hi David
Not sure what you are getting at. You can set up a parallel circuit
that can be resonant on any frequency with minor change to its construction
ala a slight inductance change so there is no need to operate on a non
resonant frequency which is what I see as a huge
plus. Remember I view the parallel circuit in its macro sense in that it is
the radiator.My antennas work that way and computor programs seem to agree
with that position. Can you supply a circuit in radiator form that acts as
you describe so I can see how it differs ?
Appreciate the input as there are only a few real experts and none have sort
to disagree which is a first for this group. Kudoes to you and Richard who
are able to provide honest thought here others are stumped.
Regards
Art



"Dave Shrader" wrote in message
news:aJR1c.45282$PR3.917056@attbi_s03...
aunwin wrote:

Why must only series circuits be considered for radiators?.

Just thinking out loud. I'm not sure I'm correct but the following seems
to make a little sense.

In a series resonant circuit the net reactance is zero. As the frequency
is changed slightly from resonance the reactance increases slowly from
zero. This is algebraic addition of plus and minus terms.

In a parallel circuit the net reactance is the product of the two terms
divided by the sum [and has a high net value]. As the frequency is
changed slightly from resonance the net reactance does not change from
'zero' it changes from a high value to a lower value.

My conclusion is that a series circuit more closely matches actual
antenna performance as the antenna impedance varies from resonance.

DD

SNIPPED

aunwin wrote:
Not sure what you are getting at.

Well, how about this, Art? A 1/2WL dipole is similar to a series circuit,
i.e. low resistance increasing to each side. A one wavelength dipole is similar
to a parallel circuit, i.e. high resistance decreasing to each side.
--
73, Cecil http://www.qsl.net/w5dxp



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Thanks for responding Cecil I know that you can't be intimidated
to say something that you disagree with.
Now the dipole, arrangement doesn't change as you change in length.
Well, put it another way, I need more input than that for me to ride on the
same train with confidence. At the moment I am losing total confidence in
myself because of the unity of others in thought that opposes mine.
Especially when some are much better educated than I. But then you said
SIMILAR, you did NOT say it changed to parallel, so I can agree with
'similar' when comparing a particular characteristic
Cheers
Art


"Cecil Moore" wrote in message
...
aunwin wrote:
Not sure what you are getting at.

Well, how about this, Art? A 1/2WL dipole is similar to a series circuit,
i.e. low resistance increasing to each side. A one wavelength dipole is
similar
to a parallel circuit, i.e. high resistance decreasing to each side.
--
73, Cecil http://www.qsl.net/w5dxp



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Art, KB9MZ wrote:
"Well that is news to me. I never consider the matching circuit as part
of an antenna, but only a required band aid."

Art only recently changed his mind it seems. A year or so ago he was
arguing that the tuned T-matched arrangement he claimed to have invented
added gain from its radiation to that of his dipole. I said ,
"impossible because radiation from a small loop is directed in the plane
of the loop." So Art hates me.

More recently we discussed current distribution on short loaded vertical
antennas and if current had to be the same at both ends of a loading
coil. It doesn`t. Yuri presented in evidence Fig 9-22 from page 9-15 of
the 2nd edition of ON4UN`s "Low-Band DXing". Art shows disdain for
experts and books, so he may have paid no attention or quickly forgot.

One of the six examples in ON4UN`s figure is a continuously loaded
radiator. No doubt, no matter how feeble it is, the radiation emanates
from the loading coil which comprises the entire antenna.

Richard Clark was showing that the choice of series resonant or parallel
resonant as a model may be based on application or impedance.

A parallel resonant circuit exhibits high impedance. It is used for high
isolation as a trap, and as a phase inverter for a collinear as in the
self-resonant coil from Kraus presented by Cecil. A parallel resonant
circuit is also used to match end-fed 1/2-waves and similar high
impedance antennas. Many cheap small radios just connect the high
impedance antenna to to the hot end of the tank circuit.

The J-pole drives an end-fed 1/2-wave antenna from a short-circuited
1/4-wave stub. The stub is equivalent to a parallel resonant circuit and
exhibits a high impedance at its open-circuit end. This was another of
Richard Clark`s examples.

I regret Art fails to see the relevance of much of the accurate
information offered.

Best regards, Richard Harrison, KB5WZI

Steve
Troll??

Yes, troll.
'Doc

Richard you have started to wander again. If a matching unit is used for
matching input inpedance of a radiator and not for the purpose of radiating
then it is certainly not part of the antenna.
If the radiating circuit has some lumped loads on it which can be
varied in value then that is certainly part of the antenna. Try and stay
focussed.
Regards
Art
"Richard Harrison" wrote in message
...
Art, KB9MZ wrote:
"Well that is news to me. I never consider the matching circuit as part
of an antenna, but only a required band aid."

Art only recently changed his mind it seems. A year or so ago he was
arguing that the tuned T-matched arrangement he claimed to have invented
added gain from its radiation to that of his dipole. I said ,
"impossible because radiation from a small loop is directed in the plane
of the loop." So Art hates me.

More recently we discussed current distribution on short loaded vertical
antennas and if current had to be the same at both ends of a loading
coil. It doesn`t. Yuri presented in evidence Fig 9-22 from page 9-15 of
the 2nd edition of ON4UN`s "Low-Band DXing". Art shows disdain for
experts and books, so he may have paid no attention or quickly forgot.

One of the six examples in ON4UN`s figure is a continuously loaded
radiator. No doubt, no matter how feeble it is, the radiation emanates
from the loading coil which comprises the entire antenna.

Richard Clark was showing that the choice of series resonant or parallel
resonant as a model may be based on application or impedance.

A parallel resonant circuit exhibits high impedance. It is used for high
isolation as a trap, and as a phase inverter for a collinear as in the
self-resonant coil from Kraus presented by Cecil. A parallel resonant
circuit is also used to match end-fed 1/2-waves and similar high
impedance antennas. Many cheap small radios just connect the high
impedance antenna to to the hot end of the tank circuit.

The J-pole drives an end-fed 1/2-wave antenna from a short-circuited
1/4-wave stub. The stub is equivalent to a parallel resonant circuit and
exhibits a high impedance at its open-circuit end. This was another of
Richard Clark`s examples.

I regret Art fails to see the relevance of much of the accurate
information offered.

Best regards, Richard Harrison, KB5WZI