On Sat, 29 Jan 2005 17:04:14 GMT, "
wrote:

Buck, in my posting I refered to 20 meters and also the incoming angles and
average signals thereof coming from Europe. Thus my interest was in the
lower half of the main lobe. The thickness of the lobe of the lobe would
thus not be important,
only the contour of the underside of the lobe. It is this portion of the
lobe where a DXer referers to the fact that a db means a lot as opposed to
adding a db gain to angles contained within a lobe. Note that the thickness
of the lobe can vary even tho both anternnas may have the same take of angle
as can be seen by comparing a monster boom length antenna to that of a
stacked beam which admittedly has a feed point which is very high. When
comparing these two types an optimum would be a low feed point (1 WL) with a
small turning radius with means to compress the main lobe downwards for
those DX
signals arrive and where the 'silly' db becomes everything
Regards
Art.




"Buck" wrote in message
.. .
On 28 Jan 2005 12:48:52 -0800, "art" wrote:

Most people have added an amplifier only to find out that the
difference in signal
was very small. Thus many people deride the value of a 'silly' db gain
whereas DX'ers say that a single db extra is a lot !
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.
So where a dxer points to the extra 1db gain as being everything in
fact it is the lowering of the TOA that comes with the extra gain. In
my opinion if one designs his antenna for a lower TOA say 10 to 11
degrees then even tho its gain may well be below the dxers choise( a
very long boom or stacked antennas) the lower TOA with less gain will
show little difference
to the antenna of choics because the lower edge of the radiation lobe
will follow the same line and any extra gain provided will have the
same effect of adding an amplifier which is minimal compared to the
ability of capturing signals that arrive at low angles.
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.
What say ?
Art

Someone correct me if I am wrong, but isn't gain derived by narrowing
focussing all the energy into a more narrow path?

Besides, TOA is important to the location of an antenna in respect to
its relative position to the ground and the surrounding terrain.

I have heard that people surrounded by mountains prefer a 1/4 whip on
their cars for 2 meters and up when trying to hit repeaters due to its
higher angle of radiation, but in the flat areas, the preferred
antennas are the 5/8 wave etc due to its horizontal gain.

Being on the side of a hill, I can't use an antenna at roof-top level
with a low angel of radiation as there isn't enough power to get the
signal through the miles of land mass under my neighbor's houses.

I did an experiment when I first received my General license to see if
I could sign into the GA SSB NTS Net. I rolled out a spool of wire on
the ground approximately 1/4 wave for 3975 kc. Without a tuner I was
able to get acceptable SWR and checked into the net. I wasn't the
strongest signal but I did well enough to hold several QSOs. It
wasn't as good as my dipole when I raised one, but it worked better
than my 40 meter dipole at the time.

I believe that a horizontal dipole will have about the same TOA as a
vertical dipole when both are sufficiently high. However, the dipole
is more bidirectional and the vertical is omni directional. Therefore
the horizontal dipole may display some gain broadside over the
vertical.

I believe that Cecil's picture reinforces the idea that on HF
especially, the TOA is largely affected by the antenna's elevation
above ground.

However, I was reading in CQ or QST last year about a DX operator who
uses verticals near the sea and wins his contests because of his
antennas. He finds the best location for his antennas near the ocean.
I believe he said he had tried beams before but there is an ocean
effect that makes the verticals better suited for his operations.

That same vertical would be lousy for me as my house is on a hill that
forms a very close valley.

I used a Taylor Radio vertical years ago in this yard and it sucked.
However, when I used it in Charleston and Jacksonville, it was
fantastic (not near the ocean).

Another DX operator suggests that most people will have a better
chance of communicating with him if they use a slanted dipole pointed
in the direction of their QTH. The angle of radiation and gain make
it a great DX antenna.

Different antennas work differently depending on their locations. I
think your better question would be, what is the best antenna for my
QTH and operating style?




--
Buck
N4PGW




Ok, Art,

I think I am with you now. I just re-read all the previous posts.
Roy Lewallen first referred to the 40 meters and I think he introduced
the picture of the angles from a vertical and a dipole.

Sorry to have been so slow picking up on this, and thank you all for
your patience with me. With all this discussion, I am learning. I
echo back my thoughts at the time that may be subject to change upon
correction or even possibly due to misinformation, hihi.

I have been studying antenna theory for a while now, off and on. Not
like a college professor, just on my own. Let's start by getting back
to your original post.

You are interested in DXing on 20 meters in which most signals come in
at 11 degrees or less. Therefore antenna designers should focus their
attention, not on antenna gain, but on getting the gain to the
incident angle of radiation. You mentioned that Amps turn out to be
of little help if the antenna angle is wrong. (I'll save the amp for
another discussion and deal with the antennas.)

I have been studying about antennas for a while now. (not like a
college professor, probably more accurately I have been reading a
lot.) I understand what you are saying about the amplifier. From my
experience I have learned a simple truth. Either one has the
propagation to make a contact, or one doesn't make contact. Last year
I totally surprised myself when I called a DX station in a pileup and
he answered. I was running an FT-817 into a dipole about 65 feet
high. There have been times I couldn't break a pileup with a 400 watt
Swan on the same antenna.

Getting back to your topic, from what I understand, the terrain and
antenna elevation are as, or more, important in establishing the angle
of incidence as the antenna is. IIRC, a Yagi has a recommended
minimum height above terrain for optimum operation. I believe that 20
meters is 125 feet.

BTW, I am curious to know, from where did you get the information that
the incoming signals are at 11 degrees?

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


--
Buck
N4PGW