On Sat, 29 Jan 2005 20:35:56 -0500, "J. Mc Laughlin"
wrote:

I do not recall writing anything about power amplifiers or something
called "one way propagation."

The paragraph you quoted is the paragraph I reiterated what I thought
you were saying. All that follows was not from you, but a followup
continuing the topic.

As for DXing. I don't chase it, but I don't turn it down either. We
do seem to be in agreement that TOA isn't the most important factor.

{Break from that}

I have heard where antennas, beams in particular, have been mounted
too high and thus not been as good for the contact. I don't remember
the numbers, two to three wavelengths sounds right, but there seems to
be an optimum height for beam antennas.

Art first mentioned the amps and I threw in the one-way propagation
statement, which probably neither of which really contributes to the
real question for discussion.


--
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

Let me encourage you to build a vertical antenna and arrage a switch so
you can switch back and forth between it and your dipole. Be sure to use
a current balun or two in your dipole feedline so it doesn't become part
of the test.

Here's what I think you'll find, as I have when comparing a vertical to
a horizontal antenna. At times, one antenna will be spectacularly better
than the other -- by 20 dB or more. After a while, maybe a minute or so,
the signal on the good antenna will fade, and when you switch you'll
find that the other antenna is now a lot better than the formerly good
one, by about the same amount. This cycle can go on for quite a while.
This is likely due to polarization rotation (although multipath can
cause a similar effect, if the antennas are spaced far enough apart);
whichever antenna has the right polarization for the moment will be much
better than the other.

I don't believe you'll find any spectacular overall improvement by using
the vertical.

When doing these tests, don't make the mistake of assuming the units on
your S-meter are some particular number of dB, unless you have the
abililty to actually measure them. Any assumption you make could be WAY off.

Roy Lewallen, W7EL

Buck wrote:
I occasionally chase counties when I am sitting at my desk doing other
things and have the radio available. Right now I am using a
horizontal dipole antenna to make contacts. The downside of this is
that many times I can't hear the mobiles or they can't hear me.

I am thinking that I might be able to improve my contacts by using a
vertical antenna since most mobiles use vertical antennas. I have
heard that once the signal bounces off the ionosphere, polarity isn't
as important as it is for local communications. However, when I was
assembling a 2 meter dipole antenna, I held it horizontal and turned
it vertical. I saw the s-meter go from nothing to s-7 and the
repeater go from silent to full quieting when I did this. I can't
help but wonder how much difference it will make with the mobiles.

Thanks for the comments.

Buck
N4PGW

"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

From URL:
http://www.astronantennas.com/polarization.html

On line-of-sight (LOS) paths, it is most important that the polarization of
the antennas at both ends of the path use the same polarization. In a
linearly polarized system, a misalignment of polarization of 45 degrees will
degrade the signal up to 3 dB and if misaligned 90 degrees the attenuation
can be 20 dB or more.

--
Caveat Lector



"Buck" wrote in message
...
I occasionally chase counties when I am sitting at my desk doing other
things and have the radio available. Right now I am using a
horizontal dipole antenna to make contacts. The downside of this is
that many times I can't hear the mobiles or they can't hear me.

I am thinking that I might be able to improve my contacts by using a
vertical antenna since most mobiles use vertical antennas. I have
heard that once the signal bounces off the ionosphere, polarity isn't
as important as it is for local communications. However, when I was
assembling a 2 meter dipole antenna, I held it horizontal and turned
it vertical. I saw the s-meter go from nothing to s-7 and the
repeater go from silent to full quieting when I did this. I can't
help but wonder how much difference it will make with the mobiles.

Thanks for the comments.

Buck
N4PGW

--
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

On Sat, 29 Jan 2005 18:41:35 -0800, Roy Lewallen
wrote:

When doing these tests, don't make the mistake of assuming the units on
your S-meter are some particular number of dB, unless you have the
abililty to actually measure them. Any assumption you make could be WAY off.

Thanks. My determining factor will be making the contact when I am up
for it. Too many times I have heard an s5 or better signal but by the
time it was my turn to call, or the pileup dies down, I can't hear the
mobile. That may be the answer.

I once considered phasing the vertical and horizontal together, but
from everything I read, the advantages of one over the other often
have to do with noise not picked up due to polarity. Horizontals have
some noise, and verticals have different noise, but a combination of
the two would have it all.

Since I am dealing with 20 and 40 meters mostly, I would only concern
myself with the 20 meter vertical. 40 doesn't seem to have the
problem. It seems that if I hear them on 40 I can work them. On 20 I
might get a 5-7 reply to a 22 report or vice-versa.

If I hang the vertical here, the top will be about 65 feet above
ground. The dipole feedline will be about 15 feet away and the center
of the dipole about 50-55 feet high. I doubt they will interact with
each other.


Thanks for your comments.

--
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

Roy Lewallen wrote:
Let me encourage you to build a vertical antenna and arrage a switch
so
you can switch back and forth between it and your dipole. Be sure to
use
a current balun or two in your dipole feedline so it doesn't become
part
of the test.

Here's what I think you'll find, as I have when comparing a vertical
to
a horizontal antenna. At times, one antenna will be spectacularly
better
than the other -- by 20 dB or more. After a while, maybe a minute or
so,
the signal on the good antenna will fade, and when you switch you'll
find that the other antenna is now a lot better than the formerly
good
one, by about the same amount. This cycle can go on for quite a
while.
This is likely due to polarization rotation (although multipath can
cause a similar effect, if the antennas are spaced far enough apart);

whichever antenna has the right polarization for the moment will be
much
better than the other.

Thats pretty close...They flip flop back and forth...

I don't believe you'll find any spectacular overall improvement by
using
the vertical.

Depends on the length of the path, and the frequency. On 40m at night,
the
improvement using the vertical is spectacular *if* the path is long
enough.
But that will vary. At 500 miles, usually the dipole will win.
At 1000 miles, usually they will be about even. At 1500 miles the usual
amount
on the S meter is about 2 s units in favor of the vertical. At 4000+
miles,
can be 4 s units.
But of course, this will vary to the quality of the vertical.
In my case, was a full size ground plane, 4 radials, up 36 feet at the
base.
The dipole was at 36 feet. Same height as the base of the GP.
My 40 meter mobile antenna is almost always better than my 36 ft high
dipole
to either of the coasts. I've tested that many times to Fla.
On say a 1500 mile path, usually the vertical will hold the best
overall,
maybe 90 percent of the time, but you will see the shift where they
flip flop
for a short time, and then flip back...
Sometimes the flop will leave them about equal. When back to "normal",
the vertical will be noticably better..2 s units in that 1500 mile
case...The vertical will be better a lot larger percentage of the time,
than
the dipole. I've seen many cases where the dipole never is as loud as
the
vertical, no matter what the shift...But thats usually on the longer
paths.
The longer the path, the larger the vertical advantage. To say VK land,
I've
never seen the vertical less than 3-4 s units better than the dipole at
36 ft.
And I was on about 3 times a week to check at that time. That dipole
would have
to be a whole lot higher than 36 ft to even come close to the ground
plane I ran.

When doing these tests, don't make the mistake of assuming the units
on
your S-meter are some particular number of dB, unless you have the
abililty to actually measure them. Any assumption you make could be
WAY off.

True...I make no claim to actual db increase....But I do use switches,
and get
a good A/B comparison...BTW...I think the vertical advantage on long
paths
decreases as you go higher in frequency...Maybe cuz the dipoles are
higher in
wavelength??? Not sure...Seems to be more a lower band, nighttime
thing...The
types of propagation at night vs day may be a factor...MK

Buck wrote:
. . .
If I hang the vertical here, the top will be about 65 feet above
ground. The dipole feedline will be about 15 feet away and the center
of the dipole about 50-55 feet high. I doubt they will interact with
each other.

The dipole feedline and the vertical will interact a great deal unless
you take steps to prevent it. That would be to insert one or more
"current baluns" (otherwise known as choke baluns and common mode
chokes) in the dipole feedline.

Roy Lewallen, W7EL