On Sat, 29 Jan 2005 16:45:29 -0800, Richard Clark
wrote:

On Sat, 29 Jan 2005 19:22:12 -0500, Buck wrote:

Speaking of Yagi's and gain, I know that the gain (and inversely the
bandwidth) of a yagi is increased by extending the spacing between
elements. A wide spaced gives a little more gain than narrow spaced
elements. I believe it also narrows the beam width of the signal.

Hi Buck,

This is fine.

I don't think it affects that TOA, though, except maybe by its
relationship to the ground and its surrounding terrain.

It is unlikely that anything you do in such a small footprint will
bring any geometric change that brings even a perceptible change to
the TOA. However, by simply increasing gain, the entire lobe
structure of the antenna increases (same shape balloon, but now a
larger balloon) which does impact the TOA; but not its angle, instead
more its magnitude. This, in a sense, was the comparison Roy was
drawing upon with the different examples.

In a sense, increasing the antenna gain (all other factors held
constant) would be indistinguishable from simply boosting the
transmitter gain (or adding an Amp).

73's
Richard Clark, KB7QHC


I think you and I are in agreement except for what Art believes. (see
his statement below

I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.

He agrees that the antenna is better as it improves receive as well as
transmit, but I can't see the TOA being more important than the gain
unless it is really off by a long way. An NVIS antenna has a
different purpose than a DX antenna so he would need an antenna that
fits his needs. I am not sure what would reduce the TOA over a Yagi
unless it is a Yagi pointed downward.

Maybe what we need to be doing is asking Art what his situation is and
trying to find the antenna that best fits his needs. I can't help but
think that this question arose because he can't seem to find the
antenna that helps him make successful DX contacts.

I used a TA-33JR for years. It was a fantastic 3 element beam. It
was small, fit on my roof and could be turned by a RadShak TV Rotor.
Even though it wasn't the ideal height above ground, it made a world
of difference chasing mobiles for the WA counties award.

I try to learn a lot about antennas. I don't claim to be an expert
and certainly don't want anyone to think I am trying to make Art (or
anyone else) look like they don't know what they are talking about.

BTW, Art, have you looked at the N4GG antenna? It is on the ARRL site
for members. I built one and didn't understand it so I took it down
and made a new antenna. Then I got the details of it, but it was
promoted as being a low angle of radiation. I don't know the degrees,
though. It was certainly a much quieter antenna than the dipole.

I talked to N4GG by email. He is a real nice person.

Good luck,

Buck


--
Buck
N4PGW

Buck wrote:
. . .
He agrees that the antenna is better as it improves receive as well as
transmit, but I can't see the TOA being more important than the gain
unless it is really off by a long way. . .

It's important to realize that at HF (where atmospheric rather than
receiver noise dominates), different criteria are important for
receiving than transmitting antenna improvement.

If you simply increase the gain of an antenna without changing the
pattern (by, for example, improving the efficiency of a vertical by
adding more radials), it improves the S/N ratio at the station you're
talking to, but it doesn't help the S/N ratio at your end. The reason is
that both of you are getting noise from elsewhere. When you increase
your gain, it improves the signal at the other end, while the noise at
the other end stays the same, hence the S/N ratio improvement. But the
gain increase causes both the signal and the noise to increase at your
end, both in the same proportion. So you've improved your transmit
effectiveness but haven't improved your ability to receive. You've done
no more than you would by turning up the volume control.

The only way to improve your ability to receive at HF is to improve the
directivity of the antenna, so it has less gain in the direction the
noise, or some of the noise, is coming from compared to the direction of
the station you're talking with. Deep pattern nulls are usually an
important factor in doing this. If the signal and bulk of the noise both
come from the same direction, you're stuck. The pattern makes no
difference for transmitting, only the gain in a single direction. (I'll
ignore the possibility of multipath propagation or surface/sky wave
interference for this simplified explanation.) But for receiving, the
ability to have different gains in different directions is important.
Because the absolute gain isn't important, a small and inefficient but
rotatable antenna with some good nulls can be an excellent receiving
antenna.

At VHF/UHF, where the noise primarily comes from the receiver front end,
antenna gain helps the S/N ratio for both transmitting and receiving.

Roy Lewallen, W7EL

Roy, W7EL wrote:
"So you`ve improved your transmit effectiveness but haven`t improved
your ability to receive."

Exactly, for Roy`s mpre radials under a vertical antenna.

For horizontal antennas, it`s another matter. The horizontal
discriminates against vertically polarized signals. Both polarizations
result from ionospheric reflection of a signal of either polarization.
The most annoying noise usually originates locally and travels to the
receibver by a vertically polarized wave, the only polarization
propagated by a ground wave.

A horizontal antenna is insensitive to vertically polarized waves, so
improving its efficiency possibly improves reception of horizontally
polarized waves without a corresponding increase in noise reception.

I worked for years in a system which relayed its broadcast programs by
HF radio. This was before satellites, jets, and great recording quality.
We also needed immediate relay capability for breaking news. All HF
relay systems were horizontally polarized.

Best regards, Richard Harrison, KB5WZI

All HF relay systems were horizontally polarized.....

I wonder about the time of day and freq? I'd almost bet many were in
the daytime,
and using fairly high frequencies as far as HF. IE: 31,25,19 m, etc...
Seems the choice was as much a receiving/noise consideration rather
than absolute
signal strength.
I think the choice is much more complex than any theoretical gains seen
in modeling,
ect. In the daytime, I don't think it really matters much. So in that
case, it
would probably make sense to use horizontal to reduce local noise
pickup. That
would improve the receive s/n. As far as transmit strength, probably
not a whole
lot of difference either way.
But at night, it seems to be a different ballgame. I think the
differences in
propagation skew things towards the vertical on the low bands at night.

The farther the path, the better the advantage.
It could be stated that most horizontal wire antennas are lower to the
ground in
terms of wavelength on those bands. This is true. But you still have
cases where
people have tried the high antennas on the low bands, and still see the
verticals
usually win on long paths.
I've never tried it, but any interested could model my 36 ft high
dipole, and then
model my 10 ft center loaded mobile whip, on a ford truck.
I'd almost bet the dipole creams the mobile antenna in the model at low
angles
as far as the gain numbers shown.
But I know in the real world, that mobile beats the 36 ft high dipole
from Houston
to Jacksonville Fla at 2 AM. Yes, even I was surprised the first time I
saw it.
But I tried it over, and over again, and it was not a fluke of nature.
If you could have two 160/80/40 m antennas at 1 wave up, both with the
same exact
gain, IE: one a 1/2 wave vertical with any radials needed to equal the
ground loss
of a horizontal dipole, I'd bet money the vertical would win on long
paths 95% of
the time. It's not just a pure "gain" thing.... I think even verticals
with less gain
will win over the dipoles once the path becomes long enough. Note my
mobile...
I know for a fact from real life, if you are going to run a dipole, and
expect to
equal my 36 ft high ground plane, you better plant that puppy *WAY*
high, or you won't
have a chance. I'm talking over a 1/2 wave up. More like a full wave,
and even then
you might lose, once the path gets to about 4k or so...
BTW, these days in Houston, local noise has just as good a chance being
horizontal
as vertical...Most is powerline noise...So with my vertical, I never
really noticed
any extra noise. The s/n ratio was always better on the vertical, for
long haul.
IE: if the noise comes up 1 s unit, but the desired signal 2 s units,
the noise
is a non factor...Many times I saw no extra noise on the vertical.
MK

Mark, NM5K has raised some interesting questions. Time of day and
frequewncy?

We operated almost around the clock with both broadcasting and program
relay. For broadcast, the schedules are based on propagation predictions
and must be published far in advance. The schedule must be followed no
matter how propagation actually turns out. The best likely frequency is
picked for the path. Also scheduled is something in the next lower
frequency band and something in the next higher frequency band. For
program relay, you can make unscheduled frequency adjustments at any
time it is convenient to do so.

Triple space diversity was the method we mostly used. (3) separate
receiving antennas, spaced about 10 wavelengths apart laterally at
40-meters (400 meters) were used to receive all relayed programs. Each
antenna fed a multicoupler so that receivers could be connected without
interaction.

The three receivers tuned to a particular program (not necessarily the
same frequency) had their outputs fed to a single TDR combiner (Crosby
or Pioneer). The combiner accepted the best output of the three
receivers and rejected the other two. An operator checked the reception
regularly to see if the signal could be improved by selection of either
the upper or lower sideband, or other means.

The height of the antennas was about 20 meters. High enough for
single-hop propagation over the path at midday on the 20-meter band. We
had fixed height so it had to serve from 5 MHz to 18 MHz at all hours.
For relay, we adjusted frequencies almost 24-hours to pick those
frequencies which were working best at the time and might also be
transmitting in the next higher and/or lower band during changing
conditions For relay we used 3 to 5 KW. For broadcast we used 50 KW and
100 KW. Antennas had about 15 dBd gain on both relay path ends. For
broadcast we used 15 dBd gain on the transmitter. The receiver may have
had a wet noodle for an antenna. If it was good enough for the jammers
it was probably good enough to receive us too.

Mark also wrote:
"I`d bet money the vertical would win on the long paths 95% of the
time."

The vertical has its null directly overhead, and it has its maximum
radiation at low vertical angles from the horizontal. A hazard for the
vertical is low uncorrected soil conductivity benearh the antenna.

Put the horizontal antenna up high and it works with either low
conductivity or high conductivity soils. Low height is the hazard for
the horizontal antenna if you want DX.

Best regards, Richard Harrison, KB5WZI

Put the horizontal antenna up high and it works with either low
conductivity or high conductivity soils.

Same for the vertical.

Low height is the h azard for
the horizontal antenna if you want DX.

Yes, but even high, they aren't always the best choice on the low
bands.
In a way, I think the same can apply to the verticals. Low height is a
hazard for those too, unless you have a load of radials...:/ MK

Dear MK (NM5K):

I do not understand. Why speculate? In the over forty years that I
have been involved with the prediction of HF propagation, huge progress has
transpired in the ease with which one may investigate the issues that seem
to be of interest.

Today, one may download and run a series of computer programs that will
provide statistically significant answers to your questions. The programs
have evolved over decades and are refined.
Go to:
http://elbert.its.bldrdoc.gov/hf.html

As Reg might say: ready to run.

Numbers tell the story. Enjoy.

73 Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:

"Buck" wrote in message
...
On Sat, 29 Jan 2005 16:45:29 -0800, Richard Clark
wrote:

On Sat, 29 Jan 2005 19:22:12 -0500, Buck wrote:

Speaking of Yagi's and gain, I know that the gain (and inversely the
bandwidth) of a yagi is increased by extending the spacing between
elements. A wide spaced gives a little more gain than narrow spaced
elements. I believe it also narrows the beam width of the signal.

Hi Buck,

This is fine.

I don't think it affects that TOA, though, except maybe by its
relationship to the ground and its surrounding terrain.

It is unlikely that anything you do in such a small footprint will
bring any geometric change that brings even a perceptible change to
the TOA. However, by simply increasing gain, the entire lobe
structure of the antenna increases (same shape balloon, but now a
larger balloon) which does impact the TOA; but not its angle, instead
more its magnitude. This, in a sense, was the comparison Roy was
drawing upon with the different examples.

In a sense, increasing the antenna gain (all other factors held
constant) would be indistinguishable from simply boosting the
transmitter gain (or adding an Amp).

73's
Richard Clark, KB7QHC


I think you and I are in agreement except for what Art believes. (see
his statement below

I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.

He agrees that the antenna is better as it improves receive as well as
transmit, but I can't see the TOA being more important than the gain
unless it is really off by a long way.
But Buck that is exactly what I am talking about. Just think about what
types of antenna
can be considered a band opener. Somebody mentioned a 150 foot boom yagi
which tho
it has lots of gain it is at a low height. I suspect the lobe it is
projecting will be around 13 degrees
and the lobe will be fat suchg that the lower portion of the main lobe may
well encompass a 10 degree
signal. Another band opener will be say a three element antenna at a height
of say 150 to 200 feet.
The three element antenna is not a ground shaker but the lobe is made lower
than a normal
height antenna thus even tho the antenna is relative low gain this low gain
is directed at a low angle
say 10 to 11 degrees that can intercept signals just as the band is opening.
Another band opener is vertically stacked three element beams solely
because there is three db
gain to be had purely by stacking that can be added
to the uppermost antenna which also lowers the interception angle area by
virtue of a fatter lobe.
Now look at the band when it is well established, most antennas will now
intercept a lot of the DX signals
but at the same time many of the band opening antennas may well fail to hear
the signals as the signals
may well be coming in at a higher angle which coincides with the null
supplied between the first and
second lobe . In all of this you must take note of what Reg said in that
communicating signals must have the same hop distance which revolves around
lobe interception and not gain. If the lobe intersection of the two stations
vary by say a few hundred miles no amount of extra gain is going to make
communication possible.
I am a member of the RSGB and not the ARRL.
Regards
Art



snip.

Good luck,

Buck


--
Buck
N4PGW

On Sun, 30 Jan 2005 03:09:54 GMT, "
wrote:


But Buck that is exactly what I am talking about. Just think about what
types of antenna
can be considered a band opener. Somebody mentioned a 150 foot boom yagi
which tho
it has lots of gain it is at a low height. I suspect the lobe it is
projecting will be around 13 degrees
and the lobe will be fat suchg that the lower portion of the main lobe may
well encompass a 10 degree
signal. Another band opener will be say a three element antenna at a height
of say 150 to 200 feet.
The three element antenna is not a ground shaker but the lobe is made lower
than a normal
height antenna thus even tho the antenna is relative low gain this low gain
is directed at a low angle
say 10 to 11 degrees that can intercept signals just as the band is opening.
Another band opener is vertically stacked three element beams solely
because there is three db
gain to be had purely by stacking that can be added
to the uppermost antenna which also lowers the interception angle area by
virtue of a fatter lobe.
Now look at the band when it is well established, most antennas will now
intercept a lot of the DX signals
but at the same time many of the band opening antennas may well fail to hear
the signals as the signals
may well be coming in at a higher angle which coincides with the null
supplied between the first and
second lobe . In all of this you must take note of what Reg said in that
communicating signals must have the same hop distance which revolves around
lobe interception and not gain. If the lobe intersection of the two stations
vary by say a few hundred miles no amount of extra gain is going to make
communication possible.
I am a member of the RSGB and not the ARRL.

Fair enough, I can't know where everyone is on the internet. On the
air, I get the advantage of having their callsign. I'll be glad to
send you the antenna design if you wish. (I see that isn't your
problem here).


Regards
Art


It appeared to me that you were looking for that lower lobe, not the
higher one when the band opens. The longer the beam, the narrower its
pattern is, and like better the rejection from other directions (f/b,
f/s rejection, etc. I took that as an understood.) )While answering
both you and in part, Roy,)

from the OP:
Fact is that most long distance signals on 20 metres come in at angles
of 11 degrees or less where as the 'normal' antenna has a TOA of around
14 degrees.
end quote.

I was under the impression that you felt a need for designers to find
a lower TOA. closer to ten or eleven degrees. I am confused, there
can be no doubt of that in your minds at this point I am sure . I
do realize that at least in a yagi, as you increase the forward gain
(f/b and s/b ratios), generally by adding elements that it narrows the
forward lobe horizontally and vertically. A 150 foot boom (say 20
elements for example) beam might be perfect for picking up the lower
angle, which is what I thought you were looking for. The three
element beam will bring in higher angle signals as the lobe will have
a higher angle. A dipole will likely have even a higher, possibly a
NVIS angle. As for being quieter, I didn't define it but I mentioned
that the N4GG antenna was much quieter than my dipoles. It also has a
low angle of radiation, which fits very well with what you and Roy are
telling me. It doesn't have a high gain, in fact the designer doesn't
even try to calculate it except to say it is a little higher than a
dipole. He also said it was designed for the DX and not to expect to
chat with many nearby stations.

For a small real estate layout, I imagine that the N4GG can be used
with a dipole or small beam for continuous DX operation. Of course
the N4GG antenna is larger than a dipole. It is one wave long and has
quarter wave legs hanging off it.

.... from the OP
I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.

Are you looking for a small antenna that will pick up the DX before
the other DX hounds start piling up?


--
Buck
N4PGW

"Buck" wrote in message
...
On Sun, 30 Jan 2005 03:09:54 GMT, "
wrote:


snipArt


It appeared to me that you were looking for that lower lobe, not the
higher one when the band opens. The longer the beam, the narrower its
pattern is, and like better the rejection from other directions (f/b,
f/s rejection, etc. I took that as an understood.) )While answering
both you and in part, Roy,)

from the OP:
Fact is that most long distance signals on 20 metres come in at angles
of 11 degrees or less where as the 'normal' antenna has a TOA of around
14 degrees.
end quote.

I was under the impression that you felt a need for designers to find
a lower TOA. closer to ten or eleven degrees.

Yes, that is exactly what I said and what I mean.We need to get away from
the long boom high gain aproach which cannot be used in many places and
look at other aproaches to getting a lower lobe trajectory with a small
turning radius.
Some will say that is impossible where as I would say it is possible when
open minds
are turned to the task.
Just think of what I could be describing, a 20 metre antenna with a
ten to eleven degree TOA, turning radius of a conventional dipole and a
feed point
of something less than 75 foot high. Now thats good for small real estate
and a light duty rotor
tho the U.K. authority may baulk at the height. I have built very long boom
yagi.s. for 20 M
some with a couple of reflectors and some with as many as 13 elements but
this direction is limited
by minimal advances compared to complexity, thus my statement as to what the
hobby needs
for it to grow
Regards
Art KB9MZ........XG




I am confused, there
can be no doubt of that in your minds at this point I am sure . I
do realize that at least in a yagi, as you increase the forward gain
(f/b and s/b ratios), generally by adding elements that it narrows the
forward lobe horizontally and vertically. A 150 foot boom (say 20
elements for example) beam might be perfect for picking up the lower
angle, which is what I thought you were looking for. The three
element beam will bring in higher angle signals as the lobe will have
a higher angle. A dipole will likely have even a higher, possibly a
NVIS angle. As for being quieter, I didn't define it but I mentioned
that the N4GG antenna was much quieter than my dipoles. It also has a
low angle of radiation, which fits very well with what you and Roy are
telling me. It doesn't have a high gain, in fact the designer doesn't
even try to calculate it except to say it is a little higher than a
dipole. He also said it was designed for the DX and not to expect to
chat with many nearby stations.

For a small real estate layout, I imagine that the N4GG can be used
with a dipole or small beam for continuous DX operation. Of course
the N4GG antenna is larger than a dipole. It is one wave long and has
quarter wave legs hanging off it.

... from the OP
I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.

Are you looking for a small antenna that will pick up the DX before
the other DX hounds start piling up?


--
Buck
N4PGW