Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:

how useful is the discussion to the average reader of r.r.a.a.?

Hi Bill,

Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").

Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.


Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.

That is for certain.

A paradox.

One of my favorite words.

On Apr 28, 6:45*pm, Michael Coslo wrote:
Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:

how useful is the discussion to the average reader of r.r.a.a.?

Hi Bill,

Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").

Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, *my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.

That is for certain.

A paradox.

One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

when you take a single rf signal and split it through different
receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. I played with some simple ones years ago and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

On Wed, 28 Apr 2010 15:51:35 -0700 (PDT), K1TTT
wrote:

that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I saw that bold statement as well, and then it was treated to a fog of
support.

At some point, the RF from two antennas must combine by the time it
hits our ears. That, or diversity reception means two people
listening to two sources and then matching notes - which means the RF
from the two antennas combine on the final page draft.

So, let me put this forward.
Two antennas
feeding two separate RF chain amplifiers
both chains mixed from a single LO
two separate mixers into IF chain amplifiers
--- somewhere they have to combine ----
two IFs into two detectors
two detectors into two separate audio chain amps
each audio chain driving a speaker element.

I have (gasp!) interpolated, interpreted, simply guessed, guessed
wrong, guessed right, about this single LO. Maybe it was in the
detector at the end of the IF chain. Whatever.

So, with this duality extending from antenna(s) to speaker(s), is the
prohibition against combining the RF from two antennas merely a
syllogism?

OK, backing up that chain to the concept of two separate RF chain
amplifiers. Lets just call it one RF chain amplifier or no RF
amplifiers and straight to a mixer. Is the prohibition at the
combining of RF from two antennas located at the mixer input? No
parallel connection?

This is getting ugly because it is not about diversity, and it is not
about antennas.

73's
Richard Clark, KB7QHC

On Apr 28, 5:51*pm, K1TTT wrote:
On Apr 28, 6:45*pm, Michael Coslo wrote:



Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:

how useful is the discussion to the average reader of r.r.a.a.?

Hi Bill,

Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").

Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, *my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.

That is for certain.

A paradox.

One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

when you take a single rf signal and split it through different
receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. *I played with some simple ones years ago and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. *that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

Tom
From my viewpoint which may well be unconventional,
may I point out that both elements as well as the array as a whole is
resonant and in equilibrium.
Thus in reality, you have two separate antennas that are additive and
go to the same receiver.
The receiver uses the addition of the two current flows or two
separate flows thus picking up both linear and non linear signals. So
I would suggest that the antenna is therefore sensitive to both .
phases( ie in phase and out of phase fields).
Ww8ji is of the opinion that the program is in error by virtue of the
statement it makes since it is unable to print the truth but doesn't
provide evidence of same.I believe he is looking at an array that is
not in equilibrium to arrive at his viewpoint.
Both elements pick up the same message with one having a delay in
time due to phase change regardles of what created it, deflection or
other wise. This is no different to viewing both elements as
mechanically vibrating and because the array as a whole is in
equilibrium both will vibrate in unison
Regards
Art

K1TTT wrote:
On Apr 28, 6:45 pm, Michael Coslo wrote:
Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:
how useful is the discussion to the average reader of r.r.a.a.?
Hi Bill,
Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").
Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.
That is for certain.

A paradox.
One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

Yeah, I think I agree with Tom's practical experience/experiment. I
certainly do not think that one antenna is going to do this diversity,
because if it would, it means that there is no need for any of the
diversity systems we know about today, with double antennas, voting
and/or dual receivers.

Richard's concerns are for the definition, which I think in Art's case,
is probably important.


when you take a single rf signal and split it through different
receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. I played with some simple ones years ago

side foray here. Did you try binaural receivers? I've heard of them,
never had a chance to listen to one.


and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

- 73 de Mike N3LI -

Michael Coslo wrote:
K1TTT wrote:

and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

- 73 de Mike N3LI -

For diversity, something which you can take advantage of has to be
different between signals from two antennas. They can be at the same
physical location but, for example, have different polarization
(polarization diversity). Or they can be physically separate (space
diversity). However, a key necessity is that the signals from the two
can't be phase coherent if you're combining them. That means you have to
separately detect the two signals with receivers that aren't phase
coherent -- you can't use a single LO for both -- then combine the
signals after detection. If you do try to connect the antennas together
or convert/detect them with the same LO, you'll simply have a single
phased array antenna system.

If you're not combining them, but listening to one or the other but not
both at the same time based on some sort of voting system, you can
detect/convert them any way you want, including using the same LO.

Roy Lewallen, W7EL

Michael Coslo wrote:

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

Actually, the antennas can be co-located, they just have to have
different patterns. There are some researchers in France who did a lot
of work using an active whip next to an active loop.

A pair of crossed dipoles would probably also work, which would have the
advantage that you could use one of them to transmit with.

Jim Lux wrote:
Michael Coslo wrote:

But aside from that little foray, I have no doubt that the effects
that call for diversity antennas/receivers also call for some physical
separation of separate antennas.

Actually, the antennas can be co-located, they just have to have
different patterns. There are some researchers in France who did a lot
of work using an active whip next to an active loop.

A pair of crossed dipoles would probably also work, which would have the
advantage that you could use one of them to transmit with.

Okay, but I'd have to modify (my statement) that as there would have to
be some difference in the antennas, even if co located. Some sort of
difference that would make one antenna receive some particular signal
better than another one. The crossed dipoles are an good example.

As Roy pointed out, it depends on the parameter in question.

- 73 de Mike N3LI -

On Apr 29, 12:30*pm, Michael Coslo wrote:
K1TTT wrote:
On Apr 28, 6:45 pm, Michael Coslo wrote:
Richard Clark wrote:
On Wed, 28 Apr 2010 10:11:51 -0700 (PDT), Bill wrote:
how useful is the discussion to the average reader of r.r.a.a.?
Hi Bill,
Well, diversity antenna work is quite useful to the average reader - I
suppose (they haven't actually clamored for the discussion or
embroiled themselves in the topic, but you did couch this in terms of
"readers").
Sure, at least in a practical sense. I make use of diversity receivers
in wireless microphone work.

While these are used at UHF frequencies rather than HF, our problems are
more multipath, maybe picket fencing a bit.

So while I know better than to get into the definitions of diversity
antennas, given my meager abilities, *my guess is that if one antenna
worked better than two - or merely worked at all, we'd be using just one.

Tom's pseudo stereo looks suspiciously like a wetware version of my
wireless systems,only that they vote, whereas his signal levels are too
low for that, so he does it in his head.

Unfortunately, if we divorced the two authors who fail to offer what
Diversity means, apart from what is already accepted in convention,
then we remove the entertainment value and "readership" would likely
decline.
That is for certain.

A paradox.
One of my favorite words.

if the pseudo stereo is derived from 2 different antennas then you
have diversity reception where the separate antennas provide different
signals that may fade at different times due to polarization changes
or incident angle changes... that is what tom was driving at as a
useful diversity system, albeit at the expense of more complex
receiver hardware.

Yeah, I think I agree with Tom's practical experience/experiment. I
certainly do not think that one antenna is going to do this diversity,
because if it would, it means that there is no need for any of the
diversity systems we know about today, with double antennas, voting
and/or dual receivers.

Richard's concerns are for the definition, which I think in Art's case,
is probably important.

* when you take a single rf signal and split it through different

receive processors to shift the phase, or do different sidebands, or
just run through different high/low pass audio filters, you don't
really have diversity, you have some kind of a processing system that
makes it easier for your brain or some other decoder to sort out the
signal from the noise. *I played with some simple ones years ago

side foray here. Did you try binaural receivers? I've heard of them,
never had a chance to listen to one.

and
they can provide interesting effects that can make sorting out signals
in pileups easier, or maybe pulling signals out of the noise a bit
easier, but none of them will really prevent the multipath, arrival
angle, or polarization fading. *that is where tom was trying to point
out that any way you combine the rf from two antennas into one you
lose the advantages of the diversity of the antennas.

I agree. One of the important factors as far as I know is that the
antennas have to be in two different spots, and although I haven't
measured, (I will now that I'm really interested) I'll bet that the best
performance comes at a distance that is well related to the wavelength.
Which is to say the picket fencing I hear on a mobile two meter signal
might allow me to determine his velocity by knowing the frequency of the
picket, the frequency of the transmission, with a likely but small error
via Doppler shift.

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

* * * * - 73 de Mike N3LI -

When I was an ET in the Air Force I had a TDY assignment attached to a
project with Hughes. They were attempting to to implement in software
what Tom was doing in wetware. The purpose was to send high speed(at
the time) radar data over HF SSB . The project was a success but the
final implementation was very different from "stereo diversity"
basically because they could not program a computer to do what the
brain can do very easily.


Jimmie

JIMMIE wrote:

But aside from that little foray, I have no doubt that the effects that
call for diversity antennas/receivers also call for some physical
separation of separate antennas.

- 73 de Mike N3LI -

When I was an ET in the Air Force I had a TDY assignment attached to a
project with Hughes. They were attempting to to implement in software
what Tom was doing in wetware. The purpose was to send high speed(at
the time) radar data over HF SSB . The project was a success but the
final implementation was very different from "stereo diversity"
basically because they could not program a computer to do what the
brain can do very easily.

these days, though, it's pretty straightforward.. The whiz-bang MIMO
stuff you see in 802.11n, for instance is one flavor of diversity. Two
antennas at each end gives you 4 possible paths (A:1, A:2, B:1, B:2)
each of which will have different fading and interference properties.