Incoming radio wave polarisation
 

On Mar 17, 11:27 am, Jim Lux wrote:
Richard Harrison wrote:
Art wrote:
"I have an on order a tilting system for my antenna to probe the
polarisation of incoming signals for maximum audio clarity and gain."

That may be interesting but do you ever recall cross polarization of an
incoming ionosphere reflected signal being unreadable because
polarization was wrong?

So many different and quickly changing path variations exist in the
ionosphere that the best antenna to use is based on probability.

Or, use diversity combining. Several researchers in France have done
work with this, and discovered there's very little correlation between
the ordinary and extraordinary rays, so diversity combining is extremely
effective on HF skywave paths. They used physically co-located antennas
that had different polarization sensitivities (a loop and a whip, as I
recall).



E.A. Laporte says on page 215 of "Radio Antenna Engineering":

"To make best use of this effect (randomness of ionospheric waves) it is
desirable to employ complimentary antennas for transmitting and
receiving."

Most commercial HF circuits I`ve experienced and seen use horizontal
polarization. It is because much severe man made interference arriving
at a receiving antenna is vertically polarized.

Interference polarization is not necessarily the case. (I believe
there are measurements that show it is essentially random). More what
it is has to do with the antenna pattern of horizontal and vertical
antennas for sources at ground level and reasonably close. For example,
A horizontal antenna not too high over a ground plane has a null right
at zero elevation.



Best regards, Richard Harrison, KB5WZI

Jim'
My 160M antenna is totaly at 70 feet. Not below or above. With the
tilting and pan mechanism and a couple of relays
it is possible to automate it so that every so often it will cycle
thru all modes using the single antenna. When a louder signal arises
then it is simple to stay on that polarisation
.. This combiation thus is a reduction of land space required for two
or more separate antennas.
I was just curious as to what other hams were doing and it appears to
be nothing in this area.
Regards
Art

Incoming radio wave polarisation
 

On Mon, 17 Mar 2008 09:17:01 -0700, Jim Lux
wrote:

run through a variable combiner

Hi Jim,

As Richard pointed out, a goniometer (what, a 100 years old already?)
works fine for this. I bought one at a Ham swap when I was a
teenager. I also pointed this goniometer/antenna application out to
Arthur to demonstrate what he thought was novel was quite old (in
reference to the work of Tosi and Bellini). Arthur does not
acknowledge prior inventors, so this topic consistently re-emerges
with a fair periodicity. It should reappear around July again.

For those who want to see a schematic of the goniometer and antenna
application, here is a perfectly good example:
http://www.elektronikschule.de/~krau...ng%20-%205.htm

73's
Richard Clark, KB7QHC

Incoming radio wave polarisation
 

Richard Clark wrote:
On Mon, 17 Mar 2008 09:17:01 -0700, Jim Lux
wrote:


run through a variable combiner


Hi Jim,

As Richard pointed out, a goniometer (what, a 100 years old already?)
works fine for this.

A potential problem with a goniometers is that they aren't particularly
broadband, although, I suppose that if the relative coupling ratios
change with frequency, at least they're consistent.

The example cited below is an example of this. You adjust for best
null/peak on your desired signal, which is narrow band. The setting for
one frequency isn't likely to be the same as the setting for another
frequency.

In an application where you want to combine multiple skywave paths, one
probably wants something that can be automatically adjusted.



I bought one at a Ham swap when I was a
teenager. I also pointed this goniometer/antenna application out to
Arthur to demonstrate what he thought was novel was quite old (in
reference to the work of Tosi and Bellini). Arthur does not
acknowledge prior inventors, so this topic consistently re-emerges
with a fair periodicity. It should reappear around July again.

For those who want to see a schematic of the goniometer and antenna
application, here is a perfectly good example:
http://www.elektronikschule.de/~krau...ng%20-%205.htm

73's
Richard Clark, KB7QHC

Incoming radio wave polarisation
 

Art Unwin wrote:
On Mar 17, 11:27 am, Jim Lux wrote:

Richard Harrison wrote:

Art wrote:
"I have an on order a tilting system for my antenna to probe the
polarisation of incoming signals for maximum audio clarity and gain."

That may be interesting but do you ever recall cross polarization of an
incoming ionosphere reflected signal being unreadable because
polarization was wrong?

So many different and quickly changing path variations exist in the
ionosphere that the best antenna to use is based on probability.

Or, use diversity combining. Several researchers in France have done
work with this, and discovered there's very little correlation between
the ordinary and extraordinary rays, so diversity combining is extremely
effective on HF skywave paths. They used physically co-located antennas
that had different polarization sensitivities (a loop and a whip, as I
recall).




E.A. Laporte says on page 215 of "Radio Antenna Engineering":

"To make best use of this effect (randomness of ionospheric waves) it is
desirable to employ complimentary antennas for transmitting and
receiving."

Most commercial HF circuits I`ve experienced and seen use horizontal
polarization. It is because much severe man made interference arriving
at a receiving antenna is vertically polarized.

Interference polarization is not necessarily the case. (I believe
there are measurements that show it is essentially random). More what
it is has to do with the antenna pattern of horizontal and vertical
antennas for sources at ground level and reasonably close. For example,
A horizontal antenna not too high over a ground plane has a null right
at zero elevation.




Best regards, Richard Harrison, KB5WZI


Jim'
My 160M antenna is totaly at 70 feet. Not below or above. With the
tilting and pan mechanism and a couple of relays
it is possible to automate it so that every so often it will cycle
thru all modes using the single antenna. When a louder signal arises
then it is simple to stay on that polarisation
. This combiation thus is a reduction of land space required for two
or more separate antennas.
I was just curious as to what other hams were doing and it appears to
be nothing in this area.

Lots of hams have done things with polarization diversity combining for
HF. Check out Ralph, W0RPK's site at:
http://showcase.netins.net/web/wallio/POLAR.html

He has some actual recorded levels over a 20-30 second interval on a 10m
skywave signal.

The problem with physically moving the antenna is that you need a fairly
fast positioner, since the fades (in any one polarization) are on the
order of 1 second. With a single antenna, you also don't know, a
priori, which way to move it or when to move it (is that an overall
fade, or is the polarization changing). You can use a scanning or
dithering technique (much like conical scan for high gain parabolas), as
long as the scan period is much less than the fading time scale.

With two co-located antennas, you've got lots more possibilities, and
with modern signal processing hardware, it's cheap.


(and, of course, most FM car radios use some form of diversity combining
these days, as do virtually all Wireless LAN access points)

Regards
Art

Incoming radio wave polarisation
 

On Mar 17, 12:53 pm, Art Unwin wrote:
On Mar 17, 11:27 am, Jim Lux wrote:



Richard Harrison wrote:
Art wrote:
"I have an on order a tilting system for my antenna to probe the
polarisation of incoming signals for maximum audio clarity and gain."

That may be interesting but do you ever recall cross polarization of an
incoming ionosphere reflected signal being unreadable because
polarization was wrong?

So many different and quickly changing path variations exist in the
ionosphere that the best antenna to use is based on probability.

Or, use diversity combining. Several researchers in France have done
work with this, and discovered there's very little correlation between
the ordinary and extraordinary rays, so diversity combining is extremely
effective on HF skywave paths. They used physically co-located antennas
that had different polarization sensitivities (a loop and a whip, as I
recall).

E.A. Laporte says on page 215 of "Radio Antenna Engineering":

"To make best use of this effect (randomness of ionospheric waves) it is
desirable to employ complimentary antennas for transmitting and
receiving."

Most commercial HF circuits I`ve experienced and seen use horizontal
polarization. It is because much severe man made interference arriving
at a receiving antenna is vertically polarized.

Interference polarization is not necessarily the case. (I believe
there are measurements that show it is essentially random). More what
it is has to do with the antenna pattern of horizontal and vertical
antennas for sources at ground level and reasonably close. For example,
A horizontal antenna not too high over a ground plane has a null right
at zero elevation.

Best regards, Richard Harrison, KB5WZI

Jim'
My 160M antenna is totaly at 70 feet. Not below or above. With the
tilting and pan mechanism and a couple of relays
it is possible to automate it so that every so often it will cycle
thru all modes using the single antenna. When a louder signal arises
then it is simple to stay on that polarisation
. This combiation thus is a reduction of land space required for two
or more separate antennas.
I was just curious as to what other hams were doing and it appears to
be nothing in this area.
Regards
Art

Jim, Allow mw to share my thoughts with you on my antenna design
and where my experimental trail is leading. I say experimental
because the trail cannot be pursued in the mind only unless one is
absolutely sure one knows everything
and thus cannot be faultedn
I constantly experiment to prove that my mind is correct or corrected
if experimentation proves it to be in error which thus require re
evalution
and redirection. without experimentaion you have nothing but a talking
head sitting on a couch.
My antenna is actually several antennas rolled up into one. As a
contra wound helix on top of each other we have a ambidextrious
antenna
that with tilting provides horizontal and vertical polarisation
because the windings and counter windings cancel each other out.
If one circular sign al is dominant I expected the cancellation
remainder will be added to the horizontal and vertical polarisation
signal.
At the same time eithe of the cancelled polarities can be issollated
from all otheres by shorting it out.
I also wanted purity of polarisation to which I have referred to in
the past where signals are not at 90 degrees to earth but tipped 10
degrees plus. Hopefully this will all work out as I have solve the
combination polarisation problem while keeping the readiator small
enough for three degree movement. I have to do all this to first
confirm that the direction that I am taking so I can move on to arrays
using tilted radiators
fashhioned in a a array in equilibrium where two degrees of freedom
with respect to volume which is forcasted by the combination of Gauss
with Maxwell. Obviously every structure has to have the ability of
many experiments as possible to flush out any errors in my analysis as
possible in the early stages. Fortunately my single radiator pursuit
with respect to size came out o.k. and thus with the incoming
mechanism for tilt and scan operation can now procede without the huge
mechanical difficulties imposed by planar and large radiators. This
comming portion of the experimental trail is of utmost im portance to
ensure that the comming arrays are truly in equilibrium such that the
spacings of
the individual small radiators can be reduceded over those of planar
arrays. In my work with the small signal radiator I have found it
possible to make them directive such that it may well render the idea
of small arrays as moot when considering the advances made by zeroing
on the signal polarity and pursuing a delay phase addition circuit
with what I have at present. A long trail that was started years ago
which I find very rewarding where I can now see the light at the end
of the tunnel.
Best regards
Art Unwin KB9MZ.....XG (uk)

Incoming radio wave polarisation
 

On Mon, 17 Mar 2008 11:57:21 -0700, Jim Lux
wrote:

In an application where you want to combine multiple skywave paths, one
probably wants something that can be automatically adjusted.

Hi Jim,

That would be called a telephone.

The objection to adjustments being necessary is duly noted; the same
characterisitic is one that has been historically prized within the
Ham world.

My goniometer was untuned.

73's
Richard Clark, KB7QHC

Incoming radio wave polarisation
 

On Mar 17, 2:03 pm, Jim Lux wrote:
Art Unwin wrote:
On Mar 17, 11:27 am, Jim Lux wrote:

Richard Harrison wrote:

Art wrote:
"I have an on order a tilting system for my antenna to probe the
polarisation of incoming signals for maximum audio clarity and gain."

That may be interesting but do you ever recall cross polarization of an
incoming ionosphere reflected signal being unreadable because
polarization was wrong?

So many different and quickly changing path variations exist in the
ionosphere that the best antenna to use is based on probability.

Or, use diversity combining. Several researchers in France have done
work with this, and discovered there's very little correlation between
the ordinary and extraordinary rays, so diversity combining is extremely
effective on HF skywave paths. They used physically co-located antennas
that had different polarization sensitivities (a loop and a whip, as I
recall).

E.A. Laporte says on page 215 of "Radio Antenna Engineering":

"To make best use of this effect (randomness of ionospheric waves) it is
desirable to employ complimentary antennas for transmitting and
receiving."

Most commercial HF circuits I`ve experienced and seen use horizontal
polarization. It is because much severe man made interference arriving
at a receiving antenna is vertically polarized.

Interference polarization is not necessarily the case. (I believe
there are measurements that show it is essentially random). More what
it is has to do with the antenna pattern of horizontal and vertical
antennas for sources at ground level and reasonably close. For example,
A horizontal antenna not too high over a ground plane has a null right
at zero elevation.

Best regards, Richard Harrison, KB5WZI

Jim'
My 160M antenna is totaly at 70 feet. Not below or above. With the
tilting and pan mechanism and a couple of relays
it is possible to automate it so that every so often it will cycle
thru all modes using the single antenna. When a louder signal arises
then it is simple to stay on that polarisation
. This combiation thus is a reduction of land space required for two
or more separate antennas.
I was just curious as to what other hams were doing and it appears to
be nothing in this area.

Lots of hams have done things with polarization diversity combining for
HF. Check out Ralph, W0RPK's site at:http://showcase.netins.net/web/wallio/POLAR.html

He has some actual recorded levels over a 20-30 second interval on a 10m
skywave signal.

The problem with physically moving the antenna is that you need a fairly
fast positioner, since the fades (in any one polarization) are on the
order of 1 second. With a single antenna, you also don't know, a
priori, which way to move it or when to move it (is that an overall
fade, or is the polarization changing). You can use a scanning or
dithering technique (much like conical scan for high gain parabolas), as
long as the scan period is much less than the fading time scale.

With two co-located antennas, you've got lots more possibilities, and
with modern signal processing hardware, it's cheap.

(and, of course, most FM car radios use some form of diversity combining
these days, as do virtually all Wireless LAN access points)

Regards
Art

Can't afford more land, I have to economise or do nothing
Art

Incoming radio wave polarisation
 

Jim Lux wrote:
"Interference polarization is not necessarily the case. --------For
example, A horizontal antenna not too high over a ground plane has a
null right at zero elevation."

Good point. The worst noise is likely local and arrives via ground wave.
Ground waves are vertically polarized because horizontal components of
an electric field are exactly canceled at the surface of a perfect
reflector.

Examination of the radiation patterns of horizontal antennas confirms
that they invariably have zero response at zero elevation on their best
azimuths.

From researching susceptibility of antennas to noise I came across a
statement interesting to me in Terman`s 1955 opus on page 929:

"----a loop antenna responds much less to the electric induction field
than does a simple wire antenna of comparable intercept area. This is of
importance because electric induction fields predominate in the man-made
noise that causes disturbances in radio receivers, and this explains in
part the popularity of loop antennas in broadcast receivers."

Best regards, Richard Harrison, KB5WZI

Incoming radio wave polarisation
 

Richard Clark wrote:
On Mon, 17 Mar 2008 11:57:21 -0700, Jim Lux
wrote:


In an application where you want to combine multiple skywave paths, one
probably wants something that can be automatically adjusted.


Hi Jim,

That would be called a telephone.

Or a reliable communications system.

The objection to adjustments being necessary is duly noted; the same
characterisitic is one that has been historically prized within the
Ham world.

More knobs better?

My goniometer was untuned.


Most Iv'e seen are basically just coils and not designed to be narrow
band. My comment was more that the transfer function varies not only as
a function of the moving coil position, but also frequency. I suppose
one could build a tuned one.


73's
Richard Clark, KB7QHC

Incoming radio wave polarisation
 

Examination of the radiation patterns of horizontal antennas confirms
that they invariably have zero response at zero elevation on their best
azimuths.
_____________

If this were true then most television broadcast stations would have nearly
zero field strength near the earth over much of their present coverage
areas.

Instead, the fields there are directly related to the peak ERP of the TV
station -- which typically is radiated in, or a few tenths of a degree below
the horizontal plane.

RF