On Aug 10, 9:04*am, "christofire" wrote:
"Art Unwin" wrote in message

...

The majority of antennas used today are (commercial) circularly polarized

That probably isn't true for VHF/UHF. *Take a look at the website of a major
supplier of professional antennas such ashttp://www.amphenol-jaybeam.com/base-station-antennas-search.php. *Entering
CP in their search engine for base-station antennas yielded 2 results wheras
entering VP yielded 365!

One of the reasons for greater use of linear polarisations in professional
applications is frequency re-use on the orthogonal polarisation some
distance away - i.e. the value of the limited VHF/UHF spectrum. *That's
certainly true in Europe.

Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?

Extensive use is made of 'mixed polarisation' *for transmitting VHF FM
broadcast services in Europe. *It may not be pure circular but it contains
significant vertically- and horizontally-polarised components. *The mobile
and portable receiving antennas have whatever polarisation they end up with,
more or less by accident, and fixed rooftop antennas are usually linearly
polarised. *DAB and terrestrial television are transmitted using V or H
linear polarisation.

Chris

Hmm A bit too technical for me! When I model my antennas it
shows gain for cp being 3 db above the gains of vertical and
horizontal for the same antenna. Is that what you call "mixed
polarization? In other words, it picks up all polarizations with a
max deviation in signal strength of only 3 db.
I find it hard to make any sort of comparison when using reflective
waves at HF because it is not clear to me exactly what sort of
rotations occur at the reflections on earth and of its layers
together with possible rotation in transit in between in the absence
of true comparison experiments.

On Aug 10, 11:11*am, Art Unwin wrote:
On Aug 10, 9:04*am, "christofire" wrote:





"Art Unwin" wrote in message

....

The majority of antennas used today are (commercial) circularly polarized

That probably isn't true for VHF/UHF. *Take a look at the website of a major
supplier of professional antennas such ashttp://www.amphenol-jaybeam.com/base-station-antennas-search.php. *Entering
CP in their search engine for base-station antennas yielded 2 results wheras
entering VP yielded 365!

One of the reasons for greater use of linear polarisations in professional
applications is frequency re-use on the orthogonal polarisation some
distance away - i.e. the value of the limited VHF/UHF spectrum. *That's
certainly true in Europe.

Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?

Extensive use is made of 'mixed polarisation' *for transmitting VHF FM
broadcast services in Europe. *It may not be pure circular but it contains
significant vertically- and horizontally-polarised components. *The mobile
and portable receiving antennas have whatever polarisation they end up with,
more or less by accident, and fixed rooftop antennas are usually linearly
polarised. *DAB and terrestrial television are transmitted using V or H
linear polarisation.

Chris

Hmm * * *A bit too technical for me! *When I model my antennas it
shows *gain for cp being 3 db above the gains of vertical and
horizontal for the same antenna. Is that what you call "mixed
polarization? *In other words, it picks up all polarizations with a
max deviation in signal strength of only 3 db.
I find it hard to make any sort of comparison when using reflective
waves at HF because it is not clear to me exactly what sort of
rotations *occur at the reflections on earth and of its layers
together with possible rotation in transit in between in the absence
of true comparison experiments.- Hide quoted text -

- Show quoted text -

Describe the circular antenna you are modeling? With the gain you are
claiming it doesnt seem to be an apples to apples comparison. I
suspect you are comparing a fullwave loop to a halfwave dipole. Show
the data you are using for your model or be prepared for most to
suspect you of the usual handwaving.

Jimmie.

On Aug 11, 3:28*pm, JIMMIE wrote:
On Aug 10, 11:11*am, Art Unwin wrote:



On Aug 10, 9:04*am, "christofire" wrote:

"Art Unwin" wrote in message

....

The majority of antennas used today are (commercial) circularly polarized

That probably isn't true for VHF/UHF. *Take a look at the website of a major
supplier of professional antennas such ashttp://www.amphenol-jaybeam.com/base-station-antennas-search.php. *Entering
CP in their search engine for base-station antennas yielded 2 results wheras
entering VP yielded 365!

One of the reasons for greater use of linear polarisations in professional
applications is frequency re-use on the orthogonal polarisation some
distance away - i.e. the value of the limited VHF/UHF spectrum. *That's
certainly true in Europe.

Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?

Extensive use is made of 'mixed polarisation' *for transmitting VHF FM
broadcast services in Europe. *It may not be pure circular but it contains
significant vertically- and horizontally-polarised components. *The mobile
and portable receiving antennas have whatever polarisation they end up with,
more or less by accident, and fixed rooftop antennas are usually linearly
polarised. *DAB and terrestrial television are transmitted using V or H
linear polarisation.

Chris

Hmm * * *A bit too technical for me! *When I model my antennas it
shows *gain for cp being 3 db above the gains of vertical and
horizontal for the same antenna. Is that what you call "mixed
polarization? *In other words, it picks up all polarizations with a
max deviation in signal strength of only 3 db.
I find it hard to make any sort of comparison when using reflective
waves at HF because it is not clear to me exactly what sort of
rotations *occur at the reflections on earth and of its layers
together with possible rotation in transit in between in the absence
of true comparison experiments.- Hide quoted text -

- Show quoted text -

Describe the circular antenna you are modeling? With the gain you are
claiming it doesnt seem to be an apples to apples comparison. I
suspect you are comparing a fullwave loop to a halfwave dipole. Show
the data you are using for your model or be prepared for most to
suspect you of the usual handwaving.

Jimmie.

NO

On Aug 11, 5:10*pm, Art Unwin wrote:
On Aug 11, 3:28*pm, JIMMIE wrote:





On Aug 10, 11:11*am, Art Unwin wrote:

On Aug 10, 9:04*am, "christofire" wrote:

"Art Unwin" wrote in message

...

The majority of antennas used today are (commercial) circularly polarized

That probably isn't true for VHF/UHF. *Take a look at the website of a major
supplier of professional antennas such ashttp://www.amphenol-jaybeam.com/base-station-antennas-search.php. *Entering
CP in their search engine for base-station antennas yielded 2 results wheras
entering VP yielded 365!

One of the reasons for greater use of linear polarisations in professional
applications is frequency re-use on the orthogonal polarisation some
distance away - i.e. the value of the limited VHF/UHF spectrum. *That's
certainly true in Europe.

Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?

Extensive use is made of 'mixed polarisation' *for transmitting VHF FM
broadcast services in Europe. *It may not be pure circular but it contains
significant vertically- and horizontally-polarised components. *The mobile
and portable receiving antennas have whatever polarisation they end up with,
more or less by accident, and fixed rooftop antennas are usually linearly
polarised. *DAB and terrestrial television are transmitted using V or H
linear polarisation.

Chris

Hmm * * *A bit too technical for me! *When I model my antennas it
shows *gain for cp being 3 db above the gains of vertical and
horizontal for the same antenna. Is that what you call "mixed
polarization? *In other words, it picks up all polarizations with a
max deviation in signal strength of only 3 db.
I find it hard to make any sort of comparison when using reflective
waves at HF because it is not clear to me exactly what sort of
rotations *occur at the reflections on earth and of its layers
together with possible rotation in transit in between in the absence
of true comparison experiments.- Hide quoted text -

- Show quoted text -

Describe the circular antenna you are modeling? With the gain you are
claiming it doesnt seem to be an apples to apples comparison. I
suspect you are comparing a fullwave loop to a halfwave dipole. Show
the data you are using for your model or be prepared for most to
suspect you of the usual handwaving.

Jimmie.

NO- Hide quoted text -

- Show quoted text -

Sounds like the same old Art to me, wants opinions and help on an
antenna and he is not willing to disclose what he is really talking
about.
I would Ploink him if I could.

Jimmie

christofire wrote:
"Art Unwin" wrote in message
...
The majority of antennas used today are (commercial) circularly polarized


That probably isn't true for VHF/UHF. Take a look at the website of a major
supplier of professional antennas such as
http://www.amphenol-jaybeam.com/base...nas-search.php. Entering
CP in their search engine for base-station antennas yielded 2 results wheras
entering VP yielded 365!

One of the reasons for greater use of linear polarisations in professional
applications is frequency re-use on the orthogonal polarisation some
distance away - i.e. the value of the limited VHF/UHF spectrum. That's
certainly true in Europe.


Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?


Extensive use is made of 'mixed polarisation' for transmitting VHF FM
broadcast services in Europe. It may not be pure circular but it contains
significant vertically- and horizontally-polarised components. The mobile
and portable receiving antennas have whatever polarisation they end up with,
more or less by accident, and fixed rooftop antennas are usually linearly
polarised. DAB and terrestrial television are transmitted using V or H
linear polarisation.

Chris


Off subject I know but as a matter of interest what happens to a TX CP
antenna with a clockwise twist transmitting to a RX CP antenna with an
anticlockwise twist, over short to medium vhf/uhf paths, I would have
thought a reduction in signal ?

Pedr GW6YMS

"P.R.Humphreys" wrote in message
...
Off subject I know but as a matter of interest what happens to a TX CP
antenna with a clockwise twist transmitting to a RX CP antenna with an
anticlockwise twist, over short to medium vhf/uhf paths, I would have
thought a reduction in signal ?

Pedr GW6YMS

About the same as going from a horizontal to a vertical antenna. You loose
about 20 db of signal.
One thing a CP signal will do that a horizontal or vertical signal won't is
to reverse when it bounces off an object. That is if you are doing moon
bounce and send up a signal using right hand CP , your receiving antenna
will need to be left hand CP or you loose lots of db of signal.

Also on the satellites it is helpful to be able to change the CP from left
to right as the signal sometimes reverses depending on the angle the
satellite antenna is pointing as it passes over.

On Aug 10, 11:37*am, "Ralph Mowery"
wrote:
"P.R.Humphreys" wrote in message

...

Off subject I know but as a matter of interest what happens to a TX CP
antenna with a clockwise *twist transmitting to a RX CP antenna with an
anticlockwise twist, over short to medium vhf/uhf paths, I would have
thought a reduction in signal ?

Pedr GW6YMS

About the same as going from a horizontal to a vertical antenna. * You loose
about 20 db of signal.
One thing a CP signal will do that a horizontal or vertical signal won't *is
to reverse when it bounces off an object. *That is if you are doing moon
bounce *and send up a signal using right hand CP , your receiving antenna
will need to be left hand CP or you loose lots of db of signal.

Also on the satellites it is helpful to be able to change the CP *from left
to right as the signal sometimes reverses depending on the angle the
satellite antenna is pointing as it passes over.

Do you ever get to the point that your signal bounces off the upper
layers instead of passing thru? I note that some users of the vhf have
seen ducting effects (temp inversions?)

"Art Unwin" wrote in message
...
Do you ever get to the point that your signal bounces off the upper
layers instead of passing thru? I note that some users of the vhf have
seen ducting effects (temp inversions?)

I hae not noticed it, but will not say that it can not hapen.

I have worked Texas from NC on two meters and lots of times way to the north
on 2 and 432. I was not working the sats while that was going on.

Art Unwin wrote:
The majority of antennas used today are (commercial) circularly
polarized
Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?

Is there a CPOL advantage for atmospherically propagated HF? I can
think of some disadvantages.

On Aug 10, 5:21*pm, dave wrote:
Art Unwin wrote:
The majority of antennas used today are (commercial) circularly
polarized
Ham antennas remain in the linear domain (ala the Yagi and similar)
There are many reasons espoused in CP advantages in "point to point"
What is the main advantage hams hold over the more popular circular
polarized antennas in its "skip" type useage versus "point to point" ?

Is there a CPOL advantage for atmospherically propagated HF? *I can
think of some disadvantages.

I am all ears. Go for it