Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL

"Alfred Lorona" wrote in
:

Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

Propagation is pretty usually reciprocal. What SEEMS to be one way
conditions is usually the result of high noise (QRN or man-made) audible at
one end of the path, but not the other. I can't even remember any instance
of GENUINE one-way propagation, though I'm sure it occasionally happens.

--
Dave Oldridge+
ICQ 1800667

"Alfred Lorona" wrote in message
...
Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL

One possible explanation is in my old CQ article at
http://www.k3bu.us/propagation.htm
Generally the opinions are that it is mainly due to the difference in local
noise levels at different ends of the path, but my experience made me
believe as I tried to explain in the article.

73 Yuri, K3BU.us

"Alfred Lorona" wrote in message
...
Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL

The closst experience I have with the matter is when the guy on the other
end is putting out about 20db more power than I am. I can hear him and he
cant hear me. Recent example I was talking with one ogf my local friends on
10m another station from 3K miles comes in and starts talking with my
friend, I can hear both sides but the dx station cant hear me because I am
on low power on the other hand my friend has switched to legal limit.I cant
verify any other situation than this thayt would appear as one way
propigation.

Jimmie

Alfred Lorona wrote:
Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL

One way propagation is possible if there is an anisotropic medium in
between (like the ionosphere).

A polarized wave may get rotated in passing through the ionized medium,
then refracted differently depending on the polarization. If you
envision your launching a beam up to the ionosphere, the place on the
ground that it hits after "reflecting" would be different depending on
the polarization. If someone in the "reflected spot" sent a beam back
to you, it too would get rotated on the way, and might propagate to a
spot other than yours.


A good practical example is the glare reducing filters that rely on a
linear polarizer followed by a rotator that rotates the polarization 45
degrees. Unpolarized light coming from the display gets rotated and
then polarized, and you see half of it. Light coming from behind you
gets polarized, rotated, reflected, rotated again, so now it's 90
degrees to the linear polarizer, and blocked.

On Mon, 11 Jun 2007 22:00:14 -0700, "Alfred Lorona"
wrote:

Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL


One way Propagation: The cause of one-way propagation is a station who
uses power to overcome antenna losses. the station can be heard but
cannot hear.
--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Buck wrote:
On Mon, 11 Jun 2007 22:00:14 -0700, "Alfred Lorona"
wrote:


Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL



One way Propagation: The cause of one-way propagation is a station who
uses power to overcome antenna losses. the station can be heard but
cannot hear.

perhaps on VHF and higher where receiver noise dominates. On lower
frequencies, where atmospheric noise dominates, one could tolerate quite
a bit of loss in the antenna/feedline and still "hear" exactly the same,
since the SNR at the antenna dominates the overall situation.

A nice practical example, in use in many HF commercial, government, and
utility type stations, would be the use of an antenna that has been
broadbanded by use of lossy elements (e.g. the terminated folded dipole
sorts of things). You might take a 6-8 dB hit in the antenna loss, which
you make up by jacking up the Tx power by 6-8 dB, but you also don't
have to worry about tuners, etc. This would be particularly useful if
you were doing ALE or frequency hopping.

"Buck" wrote in message
...
On Mon, 11 Jun 2007 22:00:14 -0700, "Alfred Lorona"
wrote:

Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

tnx, AL


One way Propagation: The cause of one-way propagation is a station who
uses power to overcome antenna losses. the station can be heard but
cannot hear.
--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

Dubbed an Alligator - Big Mouth, Small Ears
Lamont - Been There Done That

On Tue, 12 Jun 2007 11:50:24 -0700, Jim Lux wrote:
Alfred Lorona wrote:
Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

One way propagation is possible if there is an anisotropic medium in
between (like the ionosphere).

A polarized wave may get rotated in passing through the ionized medium,
then refracted differently depending on the polarization. If you
envision your launching a beam up to the ionosphere, the place on the
ground that it hits after "reflecting" would be different depending on
the polarization. If someone in the "reflected spot" sent a beam back
to you, it too would get rotated on the way, and might propagate to a
spot other than yours.

Then _that_ would explain why I've seen "one way propagation" more
decidedly on 6M versus 15M or the such. I'd think reflections and
rotations would be more 'intense' at 50 Mcs., than at lower HF freqs.

I've had distant 6M ops give me 'honest' 5/9+10, 5/9+15, 5/9+20 reports
when I could only honestly give them S-4, S-5, S-6 reports. Doesn't
happen often, but I've experienced it.

73
Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

Allodoxaphobia wrote:
On Tue, 12 Jun 2007 11:50:24 -0700, Jim Lux wrote:

Alfred Lorona wrote:

Is there a site that explores/explains the latest theories on one way
propagation? The ARRL antenna book is not much help on the subject.

One way propagation is possible if there is an anisotropic medium in
between (like the ionosphere).

A polarized wave may get rotated in passing through the ionized medium,
then refracted differently depending on the polarization. If you
envision your launching a beam up to the ionosphere, the place on the
ground that it hits after "reflecting" would be different depending on
the polarization. If someone in the "reflected spot" sent a beam back
to you, it too would get rotated on the way, and might propagate to a
spot other than yours.


Then _that_ would explain why I've seen "one way propagation" more
decidedly on 6M versus 15M or the such. I'd think reflections and
rotations would be more 'intense' at 50 Mcs., than at lower HF freqs.

I've had distant 6M ops give me 'honest' 5/9+10, 5/9+15, 5/9+20 reports
when I could only honestly give them S-4, S-5, S-6 reports. Doesn't
happen often, but I've experienced it.

Very much so..

The assumption of reciprocal paths goes completely out the window when
you have polarization and anisotropic media.

Another example of nonreciprocal paths (albeit not for electromagnetic
waves) is sound travelling some distance where there is a wind shear.
The propagation velocity varies, so sound travelling "with the wind"
tends to bend down, while "against the wind" tends to bend up. Same
thing occurs, very strikingly, with temperature gradients.

I would imagine that conditions conducive to tropospheric ducting would
have similar effects, but I can't think of a non-reciprocal example off
the top of my head.

73
Jonesy