On Aug 12, 8:31*pm, tom wrote:
Art Unwin wrote:
On Aug 12, 3:42 pm, JIMMIE wrote:
On Aug 12, 3:21 pm, dave wrote:

Art Unwin wrote:
Use your own thread to ask for assistance on your question.
*Be prepared to answer why you are requesting this personal service .
I asked a question on this thread with respect to the main advantage
for hams that linear
polarization has over CP. I have no resistance to change if it can be
justified. I see
that it can pick up signals that linear antennas cannot hear because
of a 30 db attenuation
where as CP has only a 3 db attenuation!
Compared to what?
I thought he said earlirer that it had a 3 db gain

When I modeled my antenna the max gain was CP I then checked for
linear gains
on the same set up and they were 3 db down. I suppose I should have
set it up for max linear gain and then checked CP gain on the same set
up. (Made a note to myself for future). For end fed antenna, the gain
max was around 13 dbi but 10 dbi seemed to be more the norm. What
really pleased me was the near 50 ohm impedance feed.
The biggest advantage is that people with small yards will now have no
problems on getting on top band with directional antenna and be able
to use the whole band! However, regardless on the ideas I have checked
out on it I am very confident that hams will immediately will be able
to improve it in ways I have not thought of. As with all thoughts
others will say I knew that but I couldn't be bothered because once
the dots are connected
everything appears to be obvious. A jigsaw puzzle with all the parts
turned over is tremendously hard to solve. Once you have seen the
picture it is a different ball game.
The antenna is extremely quiet, and as I have mentioned before the
audio quality is such that I immediately look at the meter only to see
it on the low side. Perhaps the CP pickup
does not register the same as for linear. It is my hope that all will
tackle building one this fall
so that the improvement horizon will broaden while I am still around.

And except for his ridiculous claims he will give no details of the
antennas he makes the claims for.

You are a fraud Art.

tom
K0TAR

No, I am not Tom you are just extending your mouth. Obviously those
who give me a hard time don't get to share. There are others who do
not give me a hard time who get to share.
If you are an outsider to every thing then I understand why you lean
on the term "ridiculous"
Remember the discussion on Gauss? You never did reverse your position
which is against classical physics so you are an unproven quantity to
most with respect to antennas and radiation.
You could, ofcourse, provide a list of polarity changes upon collision
instead of your dart throwing which is never accurate. Why don't you
plonk me or are you just a nasty person?
Maybe you can start a separate thread for just you and me so you can
sound off, insult and have a good time.

Art Unwin wrote:
No, I am not Tom you are just extending your mouth. Obviously those
who give me a hard time don't get to share. There are others who do
not give me a hard time who get to share.
If you are an outsider to every thing then I understand why you lean
on the term "ridiculous"
Remember the discussion on Gauss? You never did reverse your position
which is against classical physics so you are an unproven quantity to
most with respect to antennas and radiation.

I never expressed any opinion on Gauss. More of your mid slips.

You could, ofcourse, provide a list of polarity changes upon collision

What polarity changes? I have not been in the discussion about CP
reflections, just the claims you made about CP antennas being dominant
in the commercial market, which they are not.

instead of your dart throwing which is never accurate. Why don't you
plonk me or are you just a nasty person?

I only throw darts at targets, and you give many.

Maybe you can start a separate thread for just you and me so you can
sound off, insult and have a good time.

I'd rather insult you here, since this is where you are currently
spouting your nonsense.

And it's not a good time. I feel sorry for you and wish you'd get help.

tom
K0TAR

In message
, Art
Unwin writes
On Aug 12, 3:42*pm, JIMMIE wrote:
On Aug 12, 3:21*pm, dave wrote:

Art Unwin wrote:

Use your own thread to ask for assistance on your question.
*Be prepared to answer why you are requesting this personal service .
I asked a question on this thread with respect to the main advantage
for hams that linear
polarization has over CP. I have no resistance to change if it can be
justified. I see
that it can pick up signals that linear antennas cannot hear because
of a 30 db attenuation
where as CP has only a 3 db attenuation!

Compared to what?

I thought he said earlirer that it had a 3 db gain

If you are horizontally polarized a vertical will be down 30db
theoretically than if it was horizontal and vica versa.

Where do you get 30dB from? 'Theoretically', it ought to be infinitely
down. In practice, because of reflections and things like that, it can
vary from 'a bit down' to 'a hell of a lot down'.

If the
radiator is set for CP transmissions other polarizations
will be down only 3 db theoretically.

This is correct. You are splitting the transmitter power - half power to
each orthogonal polarisation and, with a 90 degree phase shift,
producing a circularly polarised signal (instead of a 45 degree slant).

Seems obvious which is best to
have, except a lot of hams like long distance communication which
means you have to deal with reflections.
From this thread it is obvious to me that we are not sure, at this
point, what changes occur
when reflection comes about. Roy pointed out a "misconception" at
least to his findings but the fact is there is no list of known
changes that one can bank on for reflections of CP at least for the
present. If I am incorrect then please post your thoughts.
--
Ian

On Aug 13, 5:21*am, Ian Jackson
wrote:
In message
, Art
Unwin writes



On Aug 12, 3:42*pm, JIMMIE wrote:
On Aug 12, 3:21*pm, dave wrote:

Art Unwin wrote:

Use your own thread to ask for assistance on your question.
*Be prepared to answer why you are requesting this personal service .
I asked a question on this thread with respect to the main advantage
for hams that linear
polarization has over CP. I have no resistance to change if it can be
justified. I see
that it can pick up signals that linear antennas cannot hear because
of a 30 db attenuation
where as CP has only a 3 db attenuation!

Compared to what?

I thought he said earlirer that it had a 3 db gain

If you are horizontally polarized a vertical will be down 30db
theoretically than if it was horizontal and vica versa.

Where do you get 30dB from? 'Theoretically', it ought to be infinitely
down. In practice, because of reflections and things like that, it can
vary from 'a bit down' to 'a hell of a lot down'.

Correct.
A reference supplied earlier by Jeff in this thread stated "real
world
20db to 35 db" (You used the term "in practice) A manufacturer used
the figure 30 db when I followed thru on his other references which
also appeared to me as being reasonable



If the
radiator is set for CP transmissions other polarizations
will be down only 3 db theoretically.

This is correct. You are splitting the transmitter power - half power to
each orthogonal polarisation and, with a 90 degree phase shift,
producing a circularly polarised signal (instead of a 45 degree slant).

Seems obvious which is best to
have, except a lot of hams like long distance communication which
means you have to deal with reflections.
From this thread it is obvious to me that we are not sure, at this
point, what changes occur
when reflection comes about. Roy pointed out a "misconception" at
least to his findings but the fact is there is no list of known
changes that one can bank on for reflections of CP at least for the
present. If I am incorrect then please post your thoughts.

--
Ian

On Aug 11, 4:24*pm, Art Unwin wrote:
different options to what we already have.
* *All I ask of them is to share with the rest of us exactly what
happens to CP when it collides with anything in transit to a receiver.

And the information was so shared.

Jimmie

JIMMIE wrote:
On Aug 11, 4:24 pm, Art Unwin wrote:
different options to what we already have.
All I ask of them is to share with the rest of us exactly what
happens to CP when it collides with anything in transit to a receiver.

And the information was so shared.

Jimmie

They split themselves from the conspiracy to keep Art un- and
misinformed. They will pay for that.

tom
K0TAR

On Aug 15, 7:27*pm, tom wrote:
JIMMIE wrote:
On Aug 11, 4:24 pm, Art Unwin wrote:
different options to what we already have.
* *All I ask of them is to share with the rest of us exactly what
happens to CP when it collides with anything in transit to a receiver.

And the information was so shared.

Jimmie

They split themselves from the conspiracy to keep Art un- and
misinformed. *They will pay for that.

tom
K0TAR

I am just waiting for his new contraption that is going to produce
circular polarized waves on 160M and you could haul it in the trunk of
your car. I hope that when I am as old as he says he is that I will
have morre interesting things to do wiith my time than tilt at
antennas.

Jimmie

I have been looking for a decent CP design to try out on my
repeaters .
For many years I have been looking at the reasoning for FM
broadcasters having used CP pol with great success.

I also have a small indication that linear antennas (eg:linear
collinears)and non-linear antennas(eg:folded loop dipoles) by design
may have slightly different characteristics in the far field that
tend towards a greater degree of cross/CP from the mechanical design .

Anyone had good success with installing a CP repeater antenna(2m or
70cm) to assist with the deap fade nulls in mobile uplink to the
repeater.
I want to try rhp for TX and lhp for RX - anyone tried this
combination before?

wrote in message
...
I have been looking for a decent CP design to try out on my
repeaters .
For many years I have been looking at the reasoning for FM
broadcasters having used CP pol with great success.


In the UK, Band II VHF FM sound radio broadcasting began to fixed receivers
using horizontal polarisation (HP) for reasons including a belief that
interference from car ignition systems was predominantly vertically
polarised, and because it was found easier to achieve a good
omni-directional pattern in the horizontal plane from a transmitting antenna
based on a vertical slot (Babinet's principle) - several such slot antennas
were stacked vertically to obtain some gain and to avoid illuminating the
sky.

Later, as transistors became available and vehicular VHF receivers of
sensible size became practical, a new market emerged but it was poorly
served by the HP transmissions*. When local radio was launched in the UK,
in Band II, the new transmitters were equipped with antennas that radiated a
VP component as well as HP, and in time all Band II transmissions were
converted to mixed polarisation. Circular polarisation is one example of
mixed polarisation, but its ability to provide cross-polar discrimination is
not used in FM broadcasting.

Take a look at: http://downloads.bbc.co.uk/rd/pubs/reports/1970-35.pdf

The experience in other countries has probably been similar - same physics.



I also have a small indication that linear antennas (eg:linear
collinears)and non-linear antennas(eg:folded loop dipoles) by design
may have slightly different characteristics in the far field that
tend towards a greater degree of cross/CP from the mechanical design .


Huh?

* HP is less effective than VP for VHF communication with mobiles because
the ever-present ground reflection has reversed polarity (i.e. it's in
antiphase with the signal propagating over a direct path).



Anyone had good success with installing a CP repeater antenna(2m or
70cm) to assist with the deap fade nulls in mobile uplink to the
repeater.
I want to try rhp for TX and lhp for RX - anyone tried this
combination before?

If you use the same antenna for transmitting and receiving, and it is
fundamentally circularly polarised, then it will provide and respond to the
two different senses of CP automatically because the definition of the sense
of circular polarisation depends on the direction of propagation. But do
you think the horizontally-polarised component will help with deep nulls?

Chris

christofire wrote:
. . .
* HP is less effective than VP for VHF communication with mobiles because
the ever-present ground reflection has reversed polarity (i.e. it's in
antiphase with the signal propagating over a direct path).
. . .

Reflection of a CP wave results in a reversed CP wave only when the
reflection is directly normal to the reflecting surface. That's not at
all the case for typical ground reflections. What you actually get from
ground reflections is an elliptically polarized wave, likely having the
same sense as the impinging wave. In experiments I ran about 35 years
ago, I found nearly linearly polarized waves resulting from reflection
of a CP wave from a vehicle top.

A little time spent with a modeling program such as EZNEC+ can be very
educational in understanding the generation and reflection of CP waves.

Roy Lewallen, W7EL