A 150 foot boom ( say 20
elements for example) beam might be perfect for picking up t he lower
angle, which is what I thought you were looking for. The t hree
element beam will bring in higher angle signals as the lobe will
have
a higher angle. A dipole will likely have even a higher, po ssibly a
NVIS angle. ...................................


Dunno...I've never compared super long yagi's vs short ones, but I
don't
think boom length has a drastic effect on the takeoff angle...The
height above
ground is what really determines that...Same for a dipole...A dipole
has a very
low takeoff angle *if* it's high enough..The various yagi's takeoff
angles *should*
be about the same as a dipole at that same height...Or seems to me,
without
looking into it farther. MK

On Fri, 28 Jan 2005 23:25:19 -0800, Roy Lewallen
wrote:

*Sigh*

I tried.

You can lead a horse to water.....


Roy Lewallen, W7EL

Buck wrote:
On Fri, 28 Jan 2005 21:28:20 -0800, Roy Lewallen
wrote:


What does the takeoff angle have to do with which antenna is best?



That would depend on the desired contact. If you want 80 meters DX,
you want a very high antenna, if you just want to talk to your local
buddies, a lower antenna provides a better NVIS.

Verticals provide better omni-directional pattern but a slanted dipole
provides better directivity than a vertical.

Beams are obvious.

On 29 Jan 2005 21:57:40 -0800, wrote:

A 150 foot boom ( say 20
elements for example) beam might be perfect for picking up t he lower
angle, which is what I thought you were looking for. The t hree
element beam will bring in higher angle signals as the lobe will
have
a higher angle. A dipole will likely have even a higher, po ssibly a
NVIS angle. ...................................


Dunno...I've never compared super long yagi's vs short ones, but I
don't
think boom length has a drastic effect on the takeoff angle...The
height above
ground is what really determines that...Same for a dipole...A dipole
has a very
low takeoff angle *if* it's high enough..The various yagi's takeoff
angles *should*
be about the same as a dipole at that same height...Or seems to me,
without
looking into it farther. MK


I believe that the TAO is narrower, but, like you said, it is really
affected by height and terrain. The range of the TAO of a short beam
might be -25 to +25 and a long beam might be -10 to +10 degrees
relative to horizontal (assuming maximum height of the antenna).

We are in agreement here. The author wants a small footprint antenna
to have a very low TAO, but I think that elevation has more to say
than does the antenna design. A three element beam at 20 feet might
have a TAO of 14 degrees, but the only thing you can do is point the
antenna in the direction you want. I can see pointing the antenna
upwards to get a more vertical TAO, but pointing it down won't give
you a lower one. Like you say, it takes elevation for that and then
it depends on the frequency. If that elevation is 125 feet for 20
meters how can an antenna change it to a lower elevation?

Thanks for the input. I think I have been confused as to what the OP
wanted for an answer and no doubt my answers are confusing too.
Strangely enough, I am thinking that except for the desire of the OP
for a solution, everyone in here is in agreement with the technology.

73

--
Buck
N4PGW

wrote in message
oups.com...
A 150 foot boom ( say 20
elements for example) beam might be perfect for picking up t he lower
angle, which is what I thought you were looking for. The t hree
element beam will bring in higher angle signals as the lobe will
have
a higher angle. A dipole will likely have even a higher, po ssibly a
NVIS angle. ...................................


Dunno...I've never compared super long yagi's vs short ones, but I
don't
think boom length has a drastic effect on the takeoff angle...

Mark I never used the word "drastic" however the long boom antenna
will lower the TOA by around a degree. The reader has to determine
the value of this for himself. If one reviews the incomming signals in the
ARRL literature one can see the percentage of signals that come in from
Europe
at 9 thru 13 degrees.These angles by the way are not to be confused with TOA
and explains exactly why a silly db can mean a lot.
It also shows that the long boom aproach has its limits with respect to
lower
TOA and height certainly changes the TOA more in terms of less complexity.
What I am looking for is the latter method but with less emphasis on feed
point height
which will require a deflection method to achieve lower angles. I am sure
that multiple reflectors
and a single director can be manipulated to do this
Regards
Art



The
height above
ground is what really determines that...Same for a dipole...A dipole
has a very
low takeoff angle *if* it's high enough..The various yagi's takeoff
angles *should*
be about the same as a dipole at that same height...Or seems to me,
without
looking into it farther. MK

On Sun, 30 Jan 2005 05:29:13 GMT, "
wrote:

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


I see what you are asking for. I would definitely want one myself,
but the problem I see with your theory is that the antenna can't
change the earth's effect on electromagnetic waves.

I have never had a beam up 75 feet. I had a TA-33 JR up 35 feet,
about half of the height you recommend. I can't say I had the perfect
TAO, but compared to the dipole and a vertical I was using before I
got it, the beam significantly improved my operating. I was county
hunting at the time (operating with mobiles in each US county) and the
short beam made the difference between not hearing a car and
exchanging 5-9 signal reports. While it wasn't perfect or optimum, it
was an improvement. I guess that is the best we can hope for. A
better antenna for the same space.

I like building mostly wire antennas and I have a few designs in mind
and in the works. There are many to choose from to try. Maybe one of
them will be an improvement.

When it comes to making a contact, I have resigned myself to this one
fact: If there is no propagation between two points, there is no
communications. If there is enough propagation, even the poorest of
stations can communicate.

I wish you the best on your DXing and antennas. I've enjoyed the
topic.

73 for now.

Buck
N4PGW

--
Buck
N4PGW

On Sat, 29 Jan 2005 21:56:36 -0800, Roy Lewallen
wrote:

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


Would the 'ugly balun' be suitable? (wrap 8-10 turns of coax in an 8
inch diameter loop)

That is the standard 1:1 balun I use.

Thanks.

I did see a difference with my two 20 meter dipoles. I had one
stretched, say, due north (0 deg) about 55 feet and another about 45
feet stretched about 75 degrees off. The shield side of both antennas
is where they crossed. I noticed that when I lowered one antenna the
signals seemed stronger from other directions. It didn't make either
unusable though and after Francis hit Florida, I took down the lower
20 to take with me in case I needed it and never put it back up.


--
Buck
N4PGW

On 29 Jan 2005 21:51:58 -0800, wrote:


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


Thanks, that was interesting. How well do you think a 40 meter
vertical dipole will fare vs one 36 feet up with radials? The lower
end of the dipole will likely be near the ground.


--
Buck
N4PGW

On Sat, 29 Jan 2005 07:54:16 -0600, Cecil Moore
wrote:

Maybe a picture is worth a thousand words. Here's a comparison
radiation pattern for my 130 ft dipole Vs my 40m vertical with
elevated radials. In the dipole's favored direction, it's TOA
is greater than the vertical's yet the dipole radiates more
power than the vertical even at the vertical's TOA. Here's the
pictu http://www.qsl.net/w5dxp/dipvsver.htm

Exactly!

Buck wrote:
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.

2m signals don't bounce off the ionosphere. It is not clear what
band you are talking about. For sky wave communications on HF, the
polarization doesn't much matter. For ground wave communications,
polarization matters.
--
73, Cecil http://www.qsl.net/w5dxp



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On Sun, 30 Jan 2005 12:56:05 -0600, Cecil Moore
wrote:

2m signals don't bounce off the ionosphere. It is not clear what
band you are talking about. For sky wave communications on HF, the
polarization doesn't much matter. For ground wave communications,
polarization matters.
--
73, Cecil http://www.qsl.net/w5dxp


Primarily 20 meters, maybe 40 meters.

Thanks

--
Buck
N4PGW